Improvement of Intergranular Stress Corrosion Crack Susceptibility of Austenite Stainless Steel
时效处理对不同晶粒组织Al-Zn-Mg合金腐蚀性能的影响
第 55 卷第 1 期2024 年 1 月中南大学学报(自然科学版)Journal of Central South University (Science and Technology)V ol.55 No.1Jan. 2024时效处理对不同晶粒组织Al-Zn-Mg 合金腐蚀性能的影响王鹏宇1，叶凌英1, 2, 3，柯彬1，董宇1，刘胜胆1, 2, 3(1. 中南大学 材料科学与工程学院，湖南 长沙，410083；2. 中南大学 教育部有色金属材料和工程重点实验室，湖南 长沙，410083；3. 中南大学 有色金属先进结构材料与协同创新中心，长沙，410083)摘要：以中强Al-Zn-Mg 合金为研究对象，采用晶间腐蚀、电化学极化曲线测试、慢应变速率拉伸等试验，结合OM 、TEM 、SEM 、EBSD 等组织分析方法研究时效处理和晶粒组织对合金腐蚀性能的影响。
研究结果表明：随着双级时效时间的延长，再结晶晶粒合金的抗腐蚀性能逐渐提升，从欠时效处理到过时效处理，晶间腐蚀等级由4级降为2级，电化学腐蚀电流密度由27.71 μA/cm 2降为0.098 μA/cm 2，应力腐蚀指数由79.15降至18.40；纤维晶粒合金与同时效阶段的再结晶晶粒合金相比，其抗腐蚀性能显著提升，其中，晶间腐蚀最大深度降低了35.9%，电化学腐蚀电流密度降低了81.4%，年腐蚀速率降低了81.9%，应力腐蚀敏感指数降低了46.2%。
中强Al-Zn-Mg 合金腐蚀性能的提升主要源于其较低的再结晶分数和较低的大角度晶界占比。
关键词：Al-Zn-Mg ；晶粒组织；腐蚀性能中图分类号：TG146.2 文献标志码：A 开放科学(资源服务)标识码(OSID)文章编号：1672-7207（2024）01-0055-14Effect of aging treatment on the corrosion performance of Al-Zn-Mg alloys with different grain structuresWANG Pengyu 1, YE Lingying 1, 2, 3, KE Bin 1, DONG Yu 1, LIU Shengdan 1, 2, 3(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central SouthUniversity, Changsha 410083, China;3. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,Central South University, Changsha 410083, China)Abstract: The effects of aging treatment and grain structure on the corrosion performance of the alloywere收稿日期： 2023 −03 −02； 修回日期： 2023 −05 −11基金项目(Foundation item)：国家重点研发计划项目(2022YFB3403700)；河南省紧固连接技术重点实验室资助项目(JGLJ2208)(Project(2022YFB3403700) supported by the National Key Research and Development Program of China; Project(JGLJ2208) supported by Key Laboratory of Fastening Connection Technology of Henan Province)通信作者：叶凌英，博士，教授，从事高性能铝合金研究；E-mail ：******************.cnDOI: 10.11817/j.issn.1672-7207.2024.01.005引用格式： 王鹏宇, 叶凌英, 柯彬, 等 .时效处理对不同晶粒组织Al-Zn-Mg 合金腐蚀性能的影响[J].中南大学学报(自然科学版), 2024, 55(1): 55−68.Citation: WANG Pengyu, YE Lingying, KE Bin, et al. Effect of aging treatment on the corrosion performance of Al-Zn-Mg alloys with different grain structures[J]. Journal of Central South University(Science and Technology), 2024, 55(1): 55−68.第 55 卷中南大学学报(自然科学版)investigated by using the medium-strength Al-Zn-Mg alloy as the research object, and using intergranular corrosion, electrochemical polarization curve test, and slow strain rate tensile tests, combined with OM, TEM, SEM, and EBSD observations, respectively. The results show that the corrosion resistance of the recrystallized grain alloy gradually improves with the extension of the double-stage aging time, the intergranular corrosion grade decreases from grade 4to grade 2, the electrochemical corrosion current density decreases from 27.71 μA/cm2to 0.098 μA/cm2, and the stress corrosion sensitivity factor decreases from 79.15 to 18.40 when the treatment method changes from the under-aging treatment to the over-aging treatment. The corrosion resistance of the fiber grain alloy is significantly improved compared with that of the recrystallized grain alloy at the same aging stage, including a 35.9% reduction in the maximum depth of intergranular corrosion, an 81.4% reduction in the electrochemical corrosion current density, an 81.9% reduction in the annual corrosion rate, and a 46.2% reduction in the stress corrosion sensitivity index. The improvement in corrosion performance is mainly due to the lower recrystallization fraction and lower percentage of large-angle grain boundary of the medium-strength Al-Zn-Mg alloy.Key words: Al-Zn-Mg; grain structure; corrosion propertiesAl-Zn-Mg合金具有中等强度和优秀的焊接性能，广泛应用于航空航天和高铁领域[1−2]，但该类合金在服役过程中容易发生应力腐蚀、晶间腐蚀等局部腐蚀，对使用性能造成了显著影响[3−4]。
基于平台巴西劈裂试验下WC-Co硬质合金的动态响应与失效特性
㊀第43卷㊀第3期2024年3月中国材料进展MATERIALS CHINAVol.43㊀No.3Mar.2024收稿日期:2023-09-27㊀㊀修回日期:2023-11-16基金项目:中国博士后科学基金面上项目(2021M701130);襄阳市基础研究类科技计划项目(2022ABH006271);新能源汽车与智慧交通湖北省高等学校优势特色学科群项目(XKTD062023)第一作者:张㊀健,男,1988生,博士,讲师,Email:11688@ DOI :10.7502/j.issn.1674-3962.202309029基于平台巴西劈裂试验下WC-Co 硬质合金的动态响应与失效特性张㊀健1,2,张清贵3,辛红敏1,3(1.湖北文理学院纯电动汽车动力系统设计与测试湖北省重点实验室,湖北襄阳441053)(2.西北工业大学航空发动机高性能制造工业和信息化部重点实验室,陕西西安710072)(3.湖北超卓航空科技股份有限公司,湖北襄阳441000)摘㊀要:为获取WC-Co 硬质合金在动态拉伸加载下的力学性能和失效机制,设计了动态平台巴西劈裂试验㊂结果发现,WC-Co 硬质合金具有典型的弹脆性特征,且断裂应变随着加载应变率的增加而略有增加㊂在一维应力波加载下,WC-Co 硬质合金的动态抗拉强度随应变率的增加而增加,表明其应变率效应具有明显的正相关性,该效应的产生机制与典型陶瓷类材料是一致的,即由I 型裂纹的亚临界扩展决定㊂对回收破碎试样进行微观形貌观察,发现平台圆盘中间位置处微观断裂模式主要为沿晶断裂,且在拉应力作用下形成韧窝断裂形貌;在靠近加载点位置区域,受多向应力作用,材料不仅存在韧窝断裂,在单个晶粒的局部劈裂表面还存在河流花样的解理断裂㊂宏观角度上,WC-Co 硬质合金表现出明显的脆性特征,但微观角度却发现有局部塑性变形特征㊂关键词:WC-Co 硬质合金;平台巴西劈裂;动态力学性能;断裂机制中图分类号:TG135+.5㊀㊀文献标识码:A㊀㊀文章编号:1674-3962(2024)03-0259-06引用格式:张健,张清贵,辛红敏.基于平台巴西劈裂试验下WC-Co 硬质合金的动态响应与失效特性[J].中国材料进展,2024,43(3):259-264.ZHANG J,ZHANG Q G,XIN H M.Dynamic Response and Failure Characteristics of WC-Co Cemented Carbide Under Platform-BasedBrazilian Splitting Test[J].Materials China,2024,43(3):259-264.Dynamic Response and Failure Characteristics of WC-Co Cemented Carbide Under Platform-BasedBrazilian Splitting TestZHANG Jian 1,2,ZHANG Qinggui 3,XIN Hongmin 1,3(1.Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle,Hubei University of Arts andScience,Xiangyang 441053,China)(2.Key Laboratory of High Performance Manufacturing for Aero Engine,Ministry of Industry and InformationTechnology,Northwestern Polytechnical University,Xi a n 710072,China)(3.Hubei Chaozhuo Aviation Technology Co.,Ltd.,Xiangyang 441000,China)Abstract :The dynamic platform-based Brazilian splitting experiments were designed in order to obtain the mechanicalproperty and failure mechanism of WC-Co cemented carbide under dynamic tensile loading.Results show that the WC-Co cemented carbide has the typical elastic-brittle characteristic,and its failure strain increases slightly with the strain rates.The dynamic tensile strength of WC-Co cemented carbide increases with the strain rates under one-dimensional stresswave loading,which indicates that the strain rate sensitivityof the composite has obvious positive correlation.The mechanism is consistent with typical ceramic materials,which is decided by subcritical propagation of type-Icracks.The microstructure characterizing results of recycledspecimen show that the fracture mode of middle position ofplatform-based disc is mainly intergranular fracture,andforms dimple fracture by tensile stress.At the location nearloading point,the fracture microstructure not only has the中国材料进展第43卷dimple fracture,but also has river-patterned cleavage fracture for individual grains under multi-directional stress effect.From macroscopical view,the WC-Co cemented carbide shows obvious brittle characteristics,but from microscopic view,local plastic deformation characteristics exists.Key words :WC-Co cemented carbide;platform-based Brazil splitting;dynamic mechanical property;fracture mechanism1㊀前㊀言碳化钨(tungsten carbide,WC)属于高致密度硬质合金,具有高强度㊁硬度㊁熔点㊁耐磨性等优越的物理力学性能,常用于刀具㊁防护装甲㊁穿甲弹芯等军事防护构件[1-4]㊂常将金属Co 加入WC 材料中来提高材料的韧性,制备成WC-Co 硬质合金㊂何伟锋等[1]认为目前硬质合金的研究仍主要集中在制备工艺和性能方面,而针对实际工程中的应用研究较少㊂陈开远等[5]采用高温高压烧结法制备了WC-6Co 硬质合金,并通过X 射线衍射仪㊁光学显微镜和显微硬度计研究了该硬质合金的晶体结构㊁显微组织和力学性能㊂严维等[6]在WC-6Co 硬质合金中加入Mo 晶粒,发现Mo 元素能够有效抑制WC 晶粒的长大,有利于合金硬度的提升㊂周夏凉等[7]将WC-10Co4Cr 用于涂层的力学性能和断裂机理进行了研究,发现该材料在拉伸作用下主要是脆性断裂,没有明显的塑性变形,涂层中颗粒间的孔隙和微裂纹在外应力的作用下形成裂纹,裂纹沿颗粒与颗粒间的界面扩展并伴随扩展方向的偏转,最终导致涂层的断裂㊂Ettmayer [8]发现WC-Co 硬质合金的断裂韧性随晶粒尺寸的减小而增加,而材料硬度则呈相反趋势㊂Okamoto 等[9]发现晶粒尺寸在20~30μm 的WC 材料主要以塑性变形为主,而当晶粒尺寸在3~6μm 时,材料主要表现为脆性㊂通过对晶粒尺寸为20μm 的WC 材料研究发现,随着Co 含量的增加,材料弹性模量和抗压强度均逐渐降低㊂由此可知,WC-Co 硬质合金的力学性能和断裂机理主要由晶粒尺寸㊁Co 含量以及制备工艺决定㊂WC-Co 硬质合金在动态加载下的失效主要表现为脆性特性,但其拉伸力学性能和失效机制尚不明确,尤其是加载应变率对材料强度的影响[10]㊂此外,还有研究表明,对于脆性陶瓷而言,材料动态强度随应变率的增加呈指数函数形式增加,包括Al 2O 3[11]㊁SiC [12]㊁Si 3N 4[13]㊁AlN [14]等㊂同时,高应变率下陶瓷材料的断裂主要与裂纹惯性效应密切相关:陶瓷内裂纹传播始于内部大量微观缺陷,在低应变率载荷下,形核和裂纹扩展的时间相对充足;当应力波加载速率大于裂纹扩展速率时,由于裂纹需要一定的成核时间,惯性效应对微裂纹的产生和扩展的影响逐渐增大[11]㊂随着应力波加载速率的增大,惯性效应越明显,最终导致材料强度的应变速率敏感性增大㊂本文所研究WC-Co 硬质合金的WC 晶粒尺寸在3~6μm,材料在动态加载下的变形机理仍有待开展深入研究,尤其材料的应变率敏感性以及断裂机理是否会出现与陶瓷材料相似的规律仍不明确㊂本文采用霍普金森压杆实验装置完成对WC-Co 硬质合金的间接拉伸测试 动态平台巴西劈裂试验,获得材料的应力应变关系和动态拉伸强度,分析应变率对材料强度的影响机制㊂对回收圆盘试样通过扫描电镜进行组织观察,获得WC-Co 硬质合金的动态拉伸载荷下的断裂机制㊂2㊀实验设置WC-Co 硬质合金准静态加载时表现出了明显的脆性失效特征,故本工作采用一种间接拉伸方法 平台巴西劈裂试验,对材料开展动态拉伸性能测试,实验装置如图1所示㊂图1㊀动态平台巴西劈裂试验装置示意图Fig.1㊀Facility schematic of dynamic platform-based Brazilian splitting experiments㊀㊀为保证试验结果的准确性,试样端面经过仔细抛光,并保证具有良好的垂直度和平行度㊂为了减少试样㊁垫块和压杆之间的界面摩擦影响,使用MoS 2作为润滑剂㊂压杆直径均为14.5mm,入射杆和透射杆长1300mm,撞击杆长为250mm㊂压杆材质为高强钢,弹性模量200GPa,密度7850kg /m 3,泊松比为0.3,屈服强度为1500MPa,体积声速为5200m /s㊂由于WC-Co 硬质合金的强度较高,故在压杆和试样之间增加同材质垫块,垫62㊀第3期张㊀健等:基于平台巴西劈裂试验下WC-Co硬质合金的动态响应与失效特性块直径选取10.3mm,厚度为5mm㊂由于垫块与压杆满足波阻抗匹配,在一维应力波假设下,垫块对应力波的传播影响可忽略㊂为保证常应变率加载,使试样处于应力均匀状态,在入射杆端使用波形整形器,材质为紫铜,直径为6mm,厚度为2mm㊂圆盘试样的直径为12.5mm,厚度为5mm,平行度和平面度分别为0.001和0.01mm㊂为了准确直接地测量WC-Co硬质合金在动态加载过程中的应变历程,在圆盘试样两个平面中心位置对称粘贴应变片,其中,应变片尺寸为4.7mmˑ2.6mm,小于圆盘试样㊂3㊀动态力学性能3.1㊀应力应变关系由于平台巴西劈裂试验没有解析解,根据Griffith强度理论,可得圆盘试样抗拉强度σt的数值解为[15]:σt=k2PπDt(1)式中,P为临界受拉载荷,D㊁t分别为圆盘的直径和厚度,k为平台圆盘的尺寸相关系数,可用式(2)近似描述:k=(2cos3α+cosα+sinα/α)28(cosα+sinα/α)(2)当2α=0ʎ时,k=1,对应于传统的巴西圆盘的解;本文加载角采用20ʎ,此时k=0.9644㊂基于一维应力波理论,试件中心位置的拉伸应力达到转折点时对应的临界载荷P可通过入射㊁反射和透射波的应变获得:P=EA02[εi(t)+εr(t)+εt(t)](3)其中,A0为压杆的横截面面积;εi(t)㊁εr(t)和εt(t)分别为入射波㊁反射波和透射杆加载对应的应变㊂试件的加载应变率由试件中心位置应变历程εs(t)直接求导获得:ε㊃(t)=dεs(t)d t(4)图2为动态拉伸试验的典型信号㊂由图可知,由于采用了紫铜作为波形整形器,入射波为典型三角形波,加载时间约为180μs㊂由于WC-Co硬质合金的断裂应变较小,一维应力波的加载时间对试件的应力平衡有很大影响㊂矩形入射应力伴随着波的分散,会导致严重的应力集中和试件的局部断裂,从而难以获得材料真实的强度㊂Chen等[16]认为脆性材料应采用三角形波进行加载㊂由图2可知,反射波存在一个明显的平台阶段,说明此时试样处于恒应变率加载过程㊂然后,反射波出现了一个明显的拐点和陡升信号,对应圆盘试样中心位置的拉伸应变有一个明显的转折点,此时试样波阻抗急剧降低,说明WC-Co硬质合金为脆性开裂失效,随后残余应力波完全返回到入射杆中㊂图2㊀动态拉伸试验典型信号Fig.2㊀Typical signal of dynamic tensile experiment 由图3可知,在一维应力波加载下,WC-Co硬质合金的应力应变曲线表现出了典型的弹脆性特征,即材料在断裂前的变形停留在弹性阶段㊂材料的断裂应变在0.098%~0.11%,且随着加载应变率的增加而略有增加,可见材料极易发生拉伸断裂㊂材料直线段的弹性模量随应变速率的增加保持在627~633GPa㊂图3㊀WC-Co硬质合金动态拉伸加载下应力应变曲线Fig.3㊀Stress-strain curves of WC-Co cemented carbide at dynamic ten-sile loading3.2㊀应变率效应由于动态巴西劈裂试验属于间接拉伸测试,所获得的应变率范围相对有限㊂为了获得测量数据的不确定度,对实验数据引入误差分析,在每种应变率条件下试验3次有效工况,共有4种预期应变率加载㊂设某预期应变率下的实际应变率或抗拉强度为x i,平均值为μ,工况数量为N,则此应变率条件下的实验数据标准差为:162中国材料进展第43卷Std.(σj ,εj ㊃)=1N ðNi =1(x i -μ)2(5)其中,j 为预期应变率工况㊂图4为不同应变率下WC-Co 硬质合金的拉伸强度及其标准偏差㊂由图可知,在一维应力波加载下,硬质合金的动态抗拉强度随应变率的增加而增加,表明应变率效应具有明显的正相关性㊂图4㊀WC-Co 硬质合金的动态拉伸强度的应变率效应Fig.4㊀Strain rate effect of dynamic tensile strength of WC-Co cementedcarbide研究发现,一些陶瓷材料强度和应变率ε㊃之间满足如下关系[10]:σɖε㊃N(6)式中,N 为应变率敏感系数,定义N static 和N dynamic 分别为静态和动态加载下的应变率敏感系数㊂整理图4中试验数据,通过最小二乘法拟合可获得N static =0.0073和N dynamic =0.3034㊂由表1可知,本文WC-Co 硬质合金和典型陶瓷材料(Al 2O 3㊁SiC㊁AlN)的应变率效应系数一致,高应变率下WC-Co 硬质合金的拉伸强度随应变率的变化趋势也满足公式(6),说明WC-Co 硬质合金的应变率效应产生机制与典型陶瓷类材料是一致的㊂表1㊀WC-Co 硬质合金和陶瓷材料的应变率效应对比Table 1㊀Comparison of strain rate effect among WC-Co cementedcarbide and ceramic materialsMaterialN staticN dynamic WC-Co cemented carbide0.00730.3034Al 2O 3[17](Lankford 1981)0.01920.27SiC[12](Wang 2004)~00.263AlN [14](Subhash 1998)0.287研究表明,陶瓷材料力学性能与微观失效机制密切相关,如致密度㊁晶粒尺寸及分布等㊂其中,关于材料强度的应变率效应广泛认为是由微裂纹的扩展速度与加载速率之间的关系所决定的[18]㊂一般地,对于典型陶瓷材料,应变率系数N 由裂纹扩展系数n 决定,系数n 由裂纹扩展速度c 和应力强度因子K I 决定[10]:N =11+n(7)c crack =AK n I(8)因此,材料的应变率敏感系数N 受I 型裂纹的亚临界扩展决定㊂在低应变率下(ε㊃<ε㊃1),裂纹生长速率受应变率的影响较小,材料失效由主裂纹生长㊁扩展导致,对应应变率敏感系数N 介于0.005~0.02㊂当加载超过某一临界应变率时(ε㊃1<ε㊃<ε㊃2),裂纹生长和扩展将受惯性效应影响,惯性效应将阻碍亚临界裂纹的扩展,使材料主要沿主裂纹尖端方向扩展㊂惯性效应随着加载应变率的增加表现越发明显,从而造成了材料强度的应变率效应㊂此时,典型陶瓷材料的应变率敏感系数N 接近0.3㊂在图5中,在准静态加载下,材料强度增量变化缓慢;在动态加载下,材料强度的变化逐渐剧烈,WC-Co 硬质合金表现出了类似陶瓷强度的应变率变化趋势㊂图5㊀WC-Co 硬质合金强度随应变率变化关系Fig.5㊀Relationship between strength and strain rate of WC-Co ce-mented carbide4㊀失效机制回收动态拉伸试验试样,并采用扫描电子显微镜进行断面观察,分析WC-Co 硬质合金在不同加载方式下的微观断裂模式㊂由图6可知,动态巴西劈裂试验中试样被破碎成两个不完整的半圆和许多小颗粒㊂裂纹由中心起裂,主要沿加载直径向两个加载点扩展,表明圆盘的中心处于纯拉应力状态㊂由于材料的韧性较差,在两处加载点位置处于复杂应力状态,且存在应力集中现象,因此在圆盘的两个加载点附近形成了颗粒状破碎区㊂对WC-Co 硬质合金巴西劈裂实验中破碎试样进行回收,并对不完整半圆的断裂表面不同位置处进行微观结262㊀第3期张㊀健等:基于平台巴西劈裂试验下WC-Co 硬质合金的动态响应与失效特性构分析,包括中间位置(图6的②号点)及靠近加载点位置(图6的①号点)附近(图7和图8)㊂由图7可知,WC-Co 硬质合金试样在断裂表面中间位置处微观断裂模式主要为沿晶断裂,并且在拉伸应力作用下发生剧烈滑移,形成韧窝断裂(图7中D 区域),说明在此处的微观断裂带有一定韧性㊂图6㊀动态巴西劈裂加载下WC-Co 硬质合金试样的失效模式Fig.6㊀Failure mode of WC-Co cemented carbide under dynamic Brazil-ian splittingloading图7㊀巴西劈裂加载后WC-Co 硬质合金试样破碎半圆的中间位置SEM 照片Fig.7㊀SEM image of WC-Co cemented carbide on the middle fracturedsemicircle of specimen under Brazilian splitting loading如图8所示,在试件靠近加载点位置断裂区域,碎片的微观断裂形貌不仅存在韧窝断裂,在单个晶粒的劈裂表面还存在河流花样的解理断裂㊂同时,在断裂核心区域的周围晶粒存在局部微观塑性变形(图8中箭头H 标注处),单个晶粒上出现了穿晶微裂纹(图8中箭头T 标注处),在多个晶粒的大范围区域内出现了台阶状微观解理断裂(图8中S 区域)㊂5㊀结㊀论针对WC-Co 硬质合金在动态加载下的力学性能和失效机制尚不明确的问题,尤其是加载应变率对材料强度的影响,本文采用霍普金森杆实验装置完成了对WC-Co 硬质合金的动态巴西劈裂试验,重点分析了材料的动态图8㊀巴西劈裂加载后WC-Co 硬质合金试样破碎半圆靠近加载点位置SEM 照片Fig.8㊀SEM image of WC-Co cemented carbide near loading point frac-tured semicircle of specimen under Brazilian splitting loading拉伸力学性能与失效机制㊂主要结论如下:(1)对动态拉伸加载下的典型信号和应力应变曲线分析发现,WC-Co 硬质合金具有典型的弹脆性特征,即材料在断裂前的变形停留在弹性阶段㊂材料的断裂应变在0.098%~0.11%,且随着加载应变率的增加而略有增加㊂(2)在一维应力波加载下,WC-Co 硬质合金的动态抗拉强度随应变率的增加而增加,表明应变率效应具有明显的正相关性㊂而且,WC-Co 硬质合金和典型陶瓷材料(Al 2O 3㊁SiC㊁AlN)的应变率效应系数一致,说明其应变率效应产生机制与典型陶瓷类材料是一致的,即由I型裂纹的亚临界扩展决定㊂(3)对回收的破碎试样进行微观组织观察,发现试样中间位置处微观断裂模式主要为沿晶断裂,并且在拉伸应力作用下微观结构发生剧烈滑移,形成韧窝断裂;在靠近加载点位置区域,不仅存在韧窝断裂,在单个晶粒的劈裂表面还存在河流花样的解理断裂㊂参考文献㊀References[1]㊀何伟锋,杨宇辉,王珂玮,等.热加工工艺[J],2023(22):72-77.HE W F,YANG Y H,WANG K W,et al .Hot Working Technology [J],2023(22):72-77.[2]㊀SIWAK P,GARBIEC D.Transactions of Nonferrous Metals Society ofChina[J],2016,26(10):2641-2646.[3]㊀SON S J,PARK J M,PARK S H,et al .Materials Letters[J],2021,293:129683.[4]㊀李萌,弓满锋,程赞粼,等.稀有金属材料与工程[J],2023,52(7):2653-2657.LI M,GONG M F,CHENG Z L,et al .Rare Metal Materials and En-gineering[J],2023,52(7):2653-2657.[5]㊀陈开远,全利铭,何颖晗,等.稀有金属与硬质合金[J],2021,49(3):80-86.362中国材料进展第43卷CHEN K Y,QUAN L M,HE Y H,et al.Rare Metals and Cemented Carbides[J],2021,49(3):80-86.[6]㊀严维,王水龙,郭圣达,等.稀有金属与硬质合金[J],2020,48(4):73-78.YAN W,WANG S L,GUO S D,et al.Rare Metals and Cemented Carbides[J],2020,48(4):73-78.[7]㊀周夏凉,陈小明,吴燕明,等.机械工程材料[J],2015,39(10):52-55.ZHOU X L,CHEN X M,WU Y M,et al.Materials for Mechanical Engineering[J],2015,39(10):52-55.[8]㊀ETTMAYER P.Annual Review of Materials Research[J],1989,19(1):145-164.[9]㊀OKAMOTO S,NAKAZONO Y,OTSUKA K,et al.Materials Charac-terization[J],2005,55(4/5):281-287.[10]MANDEL K,RADAJEWSKI M,KRÜGER L.Materials Science andEngineering:A[J],2014,612:115-122.[11]GAO Y B,GE Y X,XU P,et al.Materials Science and Engineering:A[J],2021,826:141976.[12]WANG H,RAMESH K T.Acta Materialia[J],2004,52(2):355-367.[13]LANKFORD J.Journal of the American Ceramic Society[J],1982,65(8):C122.[14]SUBHASH G,RAVICHANDRAN G.Journal of Materials Science[J],1998,33(7):1933-1939.[15]GAO Y B,LI D C,ZHANG W,et al.International Journal of ImpactEngineering[J],2019,132:103310.[16]CHEN W N,RAJENDRAN A M,SONG B,et al.Journal of theAmerican Ceramic Society[J],2007,90(4):1005-1018. [17]LANKFORD J.Journal of the American Ceramic Society[J],1981,64(2):C33-C34.[18]GAO Y B,TANG T G,YI C H,et al.Materials&Design[J],2016,92:814-822.(编辑㊀费蒙飞)462。
Grain_Boundary_Engineering_for_Improved_Resistence_to_Intergranular_Degradation-1
Grain Boundary Engineering for Improved Resistance to Intergranular Degradation Peter LinIntegran Technologies Inc., Toronto CanadaStuart WrightEDAX-TSL, Draper, UT 84020IntroductionIntergranular degradation processes such as intergranular-cracking, -corrosion, and –creep cavitation have plagued numerous plant components in the nuclear, oil and gas, transportation, chemical and food processing industries. The occurrence of these degradation processes often leads to costly outages; protracted regulatory proceedings for system re-start, and reduced overall plant life. One solution to overcoming these challenges is to optimize microstructures of the materials used in the critical components. An approach that has proven effective in improving the resistance of material to intergranular degradation is grain boundary engineering. Grain BoundariesIt has long been recognized that grain boundaries in polycrystalline materials can possess distinct structures [1]. It is possible to describe these distinct grain boundary structures using the so-called Concident Site Lattice (CSL) model [2]. This model is based upon the misorientation of adjoining crystals, whereby at specific orientation relationships, a 3-dimensional sub-lattice, with points common to both adjoining crystalscan be achieved. The unit volume of thiscoincident site lattice relative to that of the unit cell of the single crystal lattice isdescribed by the parameter ; increasingvalues of correspond to a greater degree ofdisorder at the interface.Numerous studies [3,4] have shown that lowCSL grain boundaries (usually 29) canpossess “special” chemical, mechanical,electronic, kinetic, and energetic properties.Of particular relevance to industrialmaterials, these “special” grain boundarieshave been shown to display a highresistance, and in many cases immunity to: Figure 1 - The effect of low boundary frequency on the probability of continued intergranular crack propagation in components based on microstructural modeling [5].(1) sliding, cavitation and fracture, (2) corrosion and stress corrosion cracking, (3) sensitization, and (4) solute segregation. Models have been developed to predict the effect of the special boundary population on these various properties. An example is shown in Figure 1.“Special” low CSL grain boundaries are found to naturally occur in all materials; their frequency of occurrence being strongly dependent upon the processing history of the material (e.g., casting, deformation, recrystallization heat treatment, etc.). Figure 2 shows an OIM map where the low CSL boundaries are highlighted in color along with a plot showing the distribution of the special boundaries. Generally, materials processing is undertaken without regard to resultant “grain boundary structure distributions”, thus producing component materials with highly variable populations of “special” grain boundaries ( 25%).Grain Boundary EngineeringGrain Boundary Engineering GBE®1 is a technique for optimizing the population of “special” boundaries in an effort to improve component material performance. The steps used in the general application of grain boundary engineering are two-fold.First, identify the effect of various thermomechanical processing steps used to make acomponent material on the “special” grain boundary population. OIM is the ideal tool for the statistical characterizations of grain boundarycharacter necessary for this procedure. It caneffectively measure the fraction of specialboundaries in materials.Second, from the insights gained, modify the thermomechanical processing route to produce materials with high “special” boundarypopulations. Materials can then be qualifiedby their “special” boundary population.Several successful examples showing the improvements achieved through grainboundary engineering are shown in Figures 3 through 7.1GBE® is a registered trademark of Integran Technologies Inc., Toronto, Canada. Figure 3 – Integranular cracking susceptibility in alloy 600 -a common nuclear steam generator tubing alloy. Samples stressed in 10% NaOH at 350°C for 3000 hours [6].Figure 2 – Extract of a map showing CSL boundaries and the corresponding distribution in a copper thin film.ConclusionsThe goal of materials engineering is to identifythe effect of materials forming processes on microstructure and in turn identify the rolemicrostructure plays on the properties of amaterial. Grain boundary engineering is a goodexample of this process. It is a very effectiveapproach for tailoring the thermomechanicalprocessing used to form materials to optimizetheir performance for applications whereprevention of intergranular degradation is acritical performance parameter.OIM is an enabling technology for grain boundary engineering. With the automation of EBSD, statistically relevant distributions of grainboundaries can be practically measured. Figure 5 – Creep resistance in alloy 625 – a super alloy used in gas turbine components. Samples creep tested under a 5 ksi tensile stress applied at 700°C.Figure 6 – Stress corrosion cracking in alloy 800, a nickel based superalloy. Cross sections were sensitized for1 hour at 600°C and exposed to a boiling solution of ferric sulphate-sulphuric acid for 120 hours.Figure 7 – Conventional and GBE® PbCaSn battery grids after 40 charge-discharge cycles (0 to 1.781 Vdc) in 1.28 s.g. H 2SO 4 at 70°C.Figure 4 – Intergranular penetration depth after 500hours exposure to Na 2So 4 at 850°C and improvementin room temperature fatigue resistance in alloy 738 –an advanced aerospace material.Bibliography[1] F. Hargreaves and R.J. Hills, “Work-Softening and a Theory of Intercrystalline Cohesion”,J. Inst. Met.41 (1929) 257.[2] M.L. Kronberg and F.H. Wilson, “Secondary Recrystallization in Copper”, Trans AIME185 (1949) 501-514.[3] K.T. Aust and J.W. Rutter, Trans TMS-AIME215 (1959) 119-126.[4] G. Palumbo and K.T. Aust, in Materials Interfaces: Atomic level structure and properties.(eds. D. Wolf and S. Yip) Chapman and Hall (1989) 190.[5] G. Palumbo, E. M. Lehockey, P. Lin, U. Erb and K. T. Aust, “Grain Boundary Engineeringfor Intergranular Fracture and Creep Resistance”, Microscopy and Microanalysis (eds.G.W. Bailey et al.) San Francisco Press (1996) 362-363.[6] G. Palumbo, E. M. Lehockey, P. Lin, U. Erb and K. T. Aust, “A Grain BoundaryEngineering Approach to Materials Reliability”, MRS Proceedings of the Symposium on Interfacial Engineering for Optimized Properties, Vol. 458, (1997) 273-383.。
烧结钕铁硼永磁合金在不同酸溶液中的腐蚀行为
烧结钕铁硼永磁合金在不同酸溶液中的腐蚀行为丁霞;薛龙飞;丁开鸿;崔胜利;孙永聪;李木森【摘要】对烧结钕铁硼永磁合金在盐酸、硝酸和磷酸3种不同酸溶液中的腐蚀行为进行研究.采用扫描电镜和能谱仪观察和测试样品腐蚀前后的微观形貌和元素质量分数,用磁性测量仪测试样品侵蚀前后的磁性能.研究结果表明:烧结钕铁硼永磁合金在盐酸和磷酸溶液中呈现均匀腐蚀特征,而在硝酸溶液中其边缘腐蚀严重;在盐酸溶液中的腐蚀速率最大,在磷酸溶液中腐蚀速率最小.盐酸溶液明显腐蚀晶界富钕相,并且会在侵蚀过程中渗入基体孔隙中,造成磁体近表面的进一步腐蚀;硝酸溶液主要腐蚀主晶相,对晶界相影响不大;磷酸溶液会在烧结钕铁硼表面形成一层块状磷酸盐产物.盐酸溶液腐蚀会造成磁体剩磁和最大磁能积的明显降低,而磷酸溶液腐蚀会在一定程度上影响磁体的内禀矫顽力,硝酸溶液腐蚀对磁体磁性能的综合影响最小.【期刊名称】《中南大学学报（自然科学版）》【年(卷),期】2016(047)004【总页数】6页(P1105-1110)【关键词】烧结钕铁硼;酸溶液;腐蚀;组织结构;磁性能【作者】丁霞;薛龙飞;丁开鸿;崔胜利;孙永聪;李木森【作者单位】山东大学材料液固结构演变与加工教育部重点实验室,山东济南,250061;山东大学材料液固结构演变与加工教育部重点实验室,山东济南,250061;烟台首钢磁性材料股份有限公司,山东烟台,265500;烟台首钢磁性材料股份有限公司,山东烟台,265500;烟台首钢磁性材料股份有限公司,山东烟台,265500;山东大学材料液固结构演变与加工教育部重点实验室,山东济南,250061【正文语种】中文【中图分类】TG171作为第三代永磁材料的钕铁硼永磁合金以其高矫顽力和高磁能积被誉为“磁中之王”，自1983年问世以来，已在电机、通讯、信息等领域广泛使用［1-3］。
但是钕铁硼永磁合金中的富钕相具有很高的电化学活性，且烧结磁体的结构疏松，存在大量孔隙，因此耐腐蚀性很差［4-5］，限制了其应用。
锂离子电池高镍三元正极材料表面改性研究进展
㊀第56卷第3期郑州大学学报(理学版)Vol.56No.3㊀2024年5月J.Zhengzhou Univ.(Nat.Sci.Ed.)May 2024收稿日期:2023-08-31基金项目:国家自然科学基金面上项目(52272242)㊂第一作者:李静(2000 ),女,硕士研究生,主要从事电化学储能研究,E-mail:1650193197@㊂通信作者:许春阳(1991 ),男,讲师,主要从事电化学储能研究,E-mail:chunyangxu@㊂锂离子电池高镍三元正极材料表面改性研究进展李㊀静1,㊀梁雅文1,㊀李㊀威2,㊀叶㊀飞1,2,㊀崔鑫炜1,㊀许春阳1(1.郑州大学㊀河南先进技术研究院㊀河南郑州450003;2.新乡天力锂能股份有限公司㊀河南新乡453002)摘要:高镍三元材料存在表面结构不稳定㊁锂镍混排㊁晶间裂纹等问题,导致材料的循环性能降低以及高比容量无法充分发挥,表面包覆是解决上述问题的主要手段㊂目前的包覆材料主要有电化学惰性材料㊁离子/电子电导性材料和复合包覆材料,从这三个方面综述了高镍三元材料的表面改性研究㊂介绍了不同类型包覆材料的界面改善稳定机制㊁离子在固液界面的迁移率提升机理㊁界面副反应抑制机制以及对材料电化学性能的影响,并对高镍三元正极材料包覆改性的发展方向进行了展望㊂关键词:锂离子电池;高镍三元;正极材料;表面改性中图分类号:TM911文献标志码:A文章编号:1671-6841(2024)03-0041-08DOI :10.13705/j.issn.1671-6841.2023207Research Progress on Surface Modification of High-nickel TernaryCathode Materials for Lithium-ion BatteriesLI Jing 1,LIANG Yawen 1,LI Wei 2,YE Fei1,2,CUI Xinwei 1,XU Chunyang 1(1.Henan Institute of Advanced Technology ,Zhengzhou University ,Zhengzhou 450003,China ;2.Xinxiang Tianli Lithium Energy Co.,Ltd ,Xinxiang 453002,China )Abstract :Problems of high-nickel ternary materials such as unstable surface structure,lithium-nickelco-segregation,and intergranular cracking led to a decrease in the cycling performance of the materials and inability to fully utilize high specific capacity.Surface coating was the primary approach to address these problems.Currently,coating materials mainly included electrochemically inert materials,ion /elec-tron-conductive materials,and composite coating materials.A review was conducted on the surface modi-fication research of high-nickel ternary materials from these aspects.The mechanisms for interface im-provement and stabilization of different types of coating materials,enhancement of ion migration at the solid-liquid interface,suppression of interface side reactions,and their impacts on the electrochemical performance were introduced.The development directions of surface modification of high-nickel ternarycathode materials were also discussed.Key words :lithium-ion battery;high-nickel ternary;cathode material;surface modification0㊀引言随着化石能源的逐渐匮乏以及环境污染的日趋严峻,高性能电化学储能器件的研发已经刻不容缓㊂在众多储能器件中,锂离子电池(lithium-ion battery,LIB)具有高能量密度㊁长循环寿命和高能量转换效率,已成为电动汽车和便携式电子设备最主要的能量来源㊂在锂离子电池正极材料中,高镍三元正极材料NCM /NCA (LiNi x Co y Mn z O 2和LiNi x Co y Al z O 2,x +y +z =1)在能量密度上具有巨大优势,是动力电池市场的主导材料㊂郑州大学学报(理学版)第56卷以NCM为例,其具有α-NaFeO2型层状结构,属六方晶系,R-3m空间群㊂Ni2+㊁Co3+和Mn4+共同占据八面体中心位置,以立方密堆积方式形成层状排列[1]㊂开发高镍三元正极材料可以满足人们日益增长的能量密度需求㊂但是,高镍三元材料存在一些不足之处,包括表面结构不稳定㊁锂镍混排㊁晶间裂纹等[2]㊂为了解决上述问题,研究者们提出了各种改性策略,主要包括表面包覆㊁晶内掺杂和晶体形貌控制,这些策略在改善三元材料电化学性能方面展现出了良好的效果㊂其中,表面改性是最常用㊁最有效的方法之一㊂目前,高镍三元材料表面改性所选的包覆材料主要有电化学惰性材料㊁离子电导性材料和电子电导性材料,并在此基础上发展到复合包覆㊂本文综述了高镍三元材料的表面改性研究进展,通过介绍不同类型包覆材料的保护机制和对材料电化学性能的影响,进而剖析目前各种包覆材料的优势及存在的问题,并展望了高镍三元正极材料包覆改性的未来发展趋势㊂1㊀电化学惰性材料电化学惰性材料主要有金属氧化物㊁金属氟化物和金属磷酸盐等,它们能有效阻隔三元正极材料和电解质之间的直接接触,有助于防止HF的侵蚀和界面副反应的发生㊂1.1㊀金属氧化物包覆材料金属氧化物包覆材料主要有Al2O3㊁ZrO2㊁TiO2㊁WO3等㊂金属氧化物包覆层可以与HF反应转化为金属氟化物,达到消除HF的目的,从而降低电解液的酸性,提升电极的结构稳定性㊂但是,这些氧化物的Li+传输速率和电子导电性相对较低,会造成包覆界面电子和离子传输阻力的增加㊂Al2O3是最常用的金属氧化物包覆材料㊂Wu 等[3]通过聚合物辅助溶胶-凝胶法在NCM622材料表面上实现微孔聚合物/γ-Al2O3保护层的构建㊂这种包覆层能有效减轻NCM622材料的电极-电解液界面副反应的发生,使材料在高压循环下的电化学性能得到显著的提升,其循环稳定性和倍率性能分别比原始材料提高了22.8%和26%㊂Ma等[4]利用水热合成法制备了NCM622单晶颗粒,然后以三异丙氧基铝为铝源通过干混烧结的方法形成Al2O3包覆层㊂13nm厚的Al2O3包覆层使NCM622的放电比容量㊁倍率性能和循环性能均得到大幅度提升,但是过厚的Al2O3包覆层也会使NCM622的储锂性能降低㊂ZrO2具有较高的化学稳定性,ZrO2包覆能有效缓解电解液的分解㊂Kim等[5]给出了ZrO2包覆样品的SEM图和带隙能量图,如图1所示㊂可以看出,其通过简单的还原反应,将白色单斜ZrO2转化为黑色的缺氧四方ZrO2-x,降低了材料的能带能(图1(b)),并成功地将其修饰在高镍正极NCM811表面(图1(a))㊂黑色ZrO2-x通过电感保持Ni2+的高氧化态,有效地抑制了在高压4.5V充电过程中的气体析出㊂图1㊀ZrO2包覆样品的SEM图和带隙能量图[5] Figure1㊀SEM images and Tauc of ZrO2coated sample[5] TiO2由于其电化学性质不活泼以及具有电荷补偿作用而被用作包覆材料㊂Mo等[6]通过湿法包覆将TiO2引入NCM622样品的二次粒子表面㊂TiO2与残留的锂化合物反应生成Li2TiO3并充当隔离层,减少了副反应的发生㊂此外,通过该方法还获得了从外到内不同Ti4+浓度的扩散层,这不仅强化了初级粒子,减少了随机取向晶粒之间的间隙,所提供的包覆层还有助于将Ti4+扩散到NCM622的晶格中,从而增加了晶格层间距,使随后的Li+迁移更加容易,迁移速率有所增加,并且机械强度和界面稳定性也会更高㊂因此,NCM622样品的循环稳定性得到增强㊂WO3具有较高的电子电导率(1.76S㊃cm-1),且作为酸性氧化物,其具有更好的耐HF蚀性㊂此外,WO3还可以和锂化合物反应,有助于消除部分残留在NCM材料表面上的碱性化合物㊂Gan等[7]将一定量的WO3溶解在H2O2中,并将其分散在无24㊀第3期李㊀静,等:锂离子电池高镍三元正极材料表面改性研究进展水乙醇中,然后再和NCM811混合蒸发高温烧结,形成WO3包覆㊂研究结果表明,WO3包覆改性在一定程度上降低了NCM811的极化,提高了NCM811的倍率和循环性能㊂此外,SiO2由于具有电化学活性低㊁储量丰富㊁环境友好㊁价格低廉等优点而备受人们关注㊂其同样可以与HF反应,保护正极颗粒免受电解液的侵蚀,缓解循环过程中的表面结构退化㊂Li等[8]采用静电引力法,通过调整SiO2溶胶悬浮体与NCM715之间的电动电位,将SiO2溶胶均匀吸附在NCM715表面,然后经过热处理形成SiO2包覆层㊂NCM715表面的SiO2包覆层减少了电解液与正极之间的反应,保护了电极的层状结构,减小了界面阻抗,即使在4.5V的高截止电压下,依然能表现出良好的电化学稳定性㊂1.2㊀金属氟化物包覆材料最主要的金属氟化物包覆材料是AlF3㊂AlF3包覆层可以通过缓解晶格膨胀来抑制循环过程中的锂镍混排和锂损失㊂此外,它还可以抑制高镍三元材料在储存过程中表面残碱的产生,提高高镍三元材料与电解质之间的界面稳定性㊂传统的干法或湿法构筑的包覆层对层结构的厚度和保形性的可控性较小,因此包覆层通常是不均匀的,这会导致电极的离子和电子传输阻力增加㊂原子层沉积(atomic layer deposition,ALD)技术是一种先进的构建包覆层技术㊂此技术可以在具有较高比表面积的基材上沉积薄膜,即使几何形状不规则,也可以精确控制其沉积厚度,保证沉积的均匀性㊂Yang等[9]使用三甲基铝和HF-吡啶作为前驱体材料,然后利用ALD技术在NCM811表面上均匀地形成AlF3纳米包覆层㊂结果表明,AlF3保护层抑制了锂镍混排,稳定了NCM811的结构㊂Li等[10]通过溶液法成功合成了AlF3包覆的Li[Ni0.80Co0.15Al0.05]O2,制备过程中首先将原始的Li[Ni0.80Co0.15Al0.05]O2粉末浸入Al(NO3)3稀溶液中,然后逐滴加入NH4F溶液,通过沉淀反应形成不同包覆厚度的AlF3㊂与原始Li[Ni0.8Co0.15Al0.05]O2相比,0.5%AlF3包覆层样品在不同测试温度下均表现出较高的容量保持率和倍率性能㊂1.3㊀金属磷酸盐包覆材料金属磷酸盐包覆材料主要有AlPO4㊁MnPO4等㊂金属磷酸盐在界面附近有转化成非晶态的趋势,这个过程可抑制相变的发生,使三元材料内部和界面处的结构更加稳定,提高材料的循环稳定性㊂Tang等[11]通过简单的干混和煅烧,成功合成了AlPO4改性的NCM622㊂研究结果表明,在NCM622表面上Al和P的存在形式分别是LiAlO2和Li3PO4,它们是由AlPO4和NCM622在煅烧过程中发生化学反应产生的㊂Al取代Ni位生成LiAlO2和Li3PO4包覆层,共同稳定了NCM622的结构㊂尽管与原始NCM622相比,在0.1C倍率时初始放电比容量有所降低,但是AlPO4提高了循环性能并缓解了高温状态下的晶格应变,提升了材料的结构稳定性,降低了微裂纹的产生㊂Liu等[12]也将AlPO4在NCM811正极材料上形成Li3PO4-LiAlO2包覆层,并研究了不同AlPO4包覆量对样品的改性㊂NCM811表面形成的Li3PO4-LiAlO2保护层不仅可以减轻表面附近的层状结构退化生成盐岩相,还可以防止HF和H2O对本体材料的侵蚀,从而使材料的结构更加稳定㊂Wu等[13]首次将非水溶液中的成膜工艺用于三元正极材料AlPO4的改性,这种方法克服了沉淀方法中包覆层不均匀的难点㊂AlPO4质量分数可控制在0.2%,这远低于之前大多数文献中的含量,超薄包覆层可以最大限度地减少包覆层的形成对Li+扩散速率㊁电子电导率和能量密度的影响,但较薄的包覆层也更容易消耗殆尽㊂2㊀离子/电子电导性材料2.1㊀离子电导性材料高镍三元正极材料的倍率性能较差,主要源于Li+在层状结构中的二维扩散通路和阻碍Li+扩散的锂镍混排,这些因素限制了它们在高功率密度领域的应用㊂Huang等[14]通过溶胶-凝胶法将Li2MnO3纳米域引入初级NCM811颗粒的层状结构中,并在这种集成结构中构建许多域边界,从而形成三维离子扩散网络,Li2MnO3包覆NCM811样品的TEM图和选区电子衍射图如图2所示㊂在这种体系中,由于颗粒尺寸减小诱导出了中空结构,增加了Li+的迁移速率,同时Li2MnO3纳米域整合到NCM811基体中,阻碍了锂镍混排的形成㊂上述因素共同促成了Li+的快速传输,从而提高了NCM811的倍率性能㊂LiAlO2具有优异的Li+传输性能㊂LiAlO2包覆层不仅可以稳定正极和电解质之间的界面结构,而且由于其提供了良好的Li+脱嵌过程的传输网络,可以显著提高电化学性能㊂Tang等[15]设计了一种通过蚀刻诱导包覆层策略,在高镍NCM811正极材料上形成γ-LiAlO2保护层和Li+导电性包覆层,以提34郑州大学学报(理学版)第56卷图2㊀Li2MnO3包覆NCM811样品的TEM图和选区电子衍射图[14]Figure2㊀TEM images and selected area electrondiffraction pattern of Li2MnO3-coated NCM811[14]高其电化学性能㊂性能提升主要是由于Al3+扩散到NCM811的晶格内部,可以减轻锂镍混排并增强结构稳定性㊂LiAlO2包覆层为Li+提供了良好的传输网络,提高了结构稳定性并防止核心材料受到电解液的侵蚀㊂Li2TiO3具有较宽的工作电压㊁较高的热稳定性和快速的Li+传输动力学,被认为是有效的用于三元正极表面修饰的包覆层材料㊂He等[16]提出一种新型的Li2TiO3纳米颗粒包覆层,避免了Ti4+的掺杂造成的锂镍混排过程的恶化㊂纳米Li2TiO3包覆的NCA8155显示出几乎没有变化的形貌结构和较低的表面残碱,因此Li2TiO3包覆层显著提升了循环稳定性和倍率性能㊂最优异的表面包覆层不仅能通过阻断电解质和电极表面上高活性阳离子之间的物理接触来解决不稳定性问题,还能稳定电极中晶格氧离子,改善Li+的迁移率㊂Wang等[17]提出了一种直接调控策略,用于适应固相中的高活性阳离子㊂通过利用锂镧镍氧双离子导体(层状钙钛矿La4NiLiO8)包覆层中稳定的氧空位和间隙,显著抑制了表面晶格氧离子的活性,抑制了晶格中的氧释放以及不可逆相变和晶间机械裂纹㊂同时,引入的双离子导体还可以改善Li+在颗粒表面的扩散动力学和材料本体的电子导电性㊂另外,Li等[18]首次采用简单的一步法制备了结构和界面可靠的B掺杂和La4NiLiO8包覆改性的NCM811正极㊂La4NiLiO8包覆层可以防止电极遭受电解液的腐蚀,并提升Li+的传输动力学㊂此外, B掺杂可以有效地抑制有害的H2~H3相变,并将初级粒子的取向调整为径向排列,这阻碍了由于晶体各向异性导致的体积变化而引起的微裂纹产生㊂Yang等[19]通过一种简单的方法成功地制备了La和Al共掺杂和包覆改性的NCM811㊂XRD和XPS证实,La和Al不仅可以掺杂到NCM811本体中,而且可以在表面形成La2Li0.5Al0.5O4包覆层㊂高压电化学性能的提高主要归因于La和Al通过共掺杂增强了体相结构,形成的La2Li0.5Al0.5O4包覆层作为高T c超导氧化物,不仅促进了Li+的传输,而且保护了材料免受电解质的侵蚀㊂此外,残留的锂盐还能通过形成La2Li0.5Al0.5O4而被还原㊂电化学性能的提升表明,La2Li0.5Al0.5O4包覆层的改性和La-Al共掺杂是NCM811材料大规模工业化生产的一种有竞争力的方法㊂Wang等[20]引入晶体结构相似的钙钛矿相来 铆钉 层状结构的膨胀收缩,钉扎效应显著减轻了由于晶体结构的体积变化所带来的有害结构演变㊂与传统材料相比,每个循环中的晶格应变演变减少了近70%,这显著增强了二次颗粒的完整性,从而提高了电池的可逆循环性能㊂这种应变抑制方法拓宽了晶格工程的应用前景,以释放锂嵌(脱)产生的应变,并为开发具有长寿命的高能量密度正极铺平道路㊂Wang等[21]提出一种利用富锂和富锰层状氧化物(lithium-and manganese-rich layered oxide,LMR)的低应变材料在富镍层状氧化物(nickel-rich lay-ered oxide,NLO)正极上重建稳定表面的策略㊂新的表面结构不仅由梯度结构组成,而且形成了丰富的氧空位和阳离子有序的缺陷结构,这种结构可以同时提升Li+的扩散速率并在锂嵌(脱)过程中稳定晶体结构㊂NLO中的这些特征显著改善了电化学性能,特别是在高压循环下的稳定性㊂Tan等[22]通过在NCM811的层状相中引入尖晶石状榫卯结构,可以显著抑制正极材料中不利的体积变化㊂同时,该榫卯结构对Li+的快速传输起到了类似高速公路的作用㊂此外,具有榫卯结构的颗粒通常以最稳定的(003)面终止㊂该工作提供了一种可行的晶格工程,以解决NLO的稳定性和低首次库仑效率的问题,并有助于实现具有高能量密度和长耐久性的锂离子电池㊂Cai等[23]提出了高压诱导析氧的理论,并报道了一种镧系化过程,以调节正极材料的近表面结构,并将这种超越传统的表面修饰推广到贫钴/无钴高44㊀第3期李㊀静,等:锂离子电池高镍三元正极材料表面改性研究进展能量密度层状正极中,证明了有效的表面钝化抑制了表面降解和改善了电化学性能,高压循环稳定性大大增强,最高可达4.8V(相对于Li+/Li)㊂所设计的表面相在高电压下抑制了析氧反应㊂表明通过高氧活性钝化㊁选择性化学合金化和使用湿化学的应变工程进行改性,能获得高性能层状氧化物正极材料㊂Yang等[24]制备了Li0.5La2Al0.5O4(LLAO)原位包覆层和Mn离子补偿掺杂的多层LiNi0.82Co0.14Al0.04O2㊂XRD精修表明,La-Mn协同改性可以实现适当的锂镍混排㊂计算结果和原位XRD分析表明,LLAO包覆层能够有效地抑制二次颗粒中的机械裂纹,这得益于内部晶体应变被抑制㊂测试结果表明,LLAO-Mn改性的循环后的正极具有更完整的形貌,与电解液的副反应更少㊂进一步研究了气体析出时的正极电解质界面,表明NCA-LM2比NCA-P释放更少的CO2,从而达到更稳定的表面㊂2.2㊀电子电导性材料石墨烯具有大的比表面积㊁优异的电子导电性和机械性能,其化学性质稳定㊂石墨烯的引入可以有效地提高电极材料表面的电子电导率㊁电容性能等㊂Luo等[25]通过模板自组装法制备了一种具有三维纳米结构的NCA8155/石墨烯复合材料(G-NCA8155)㊂首先将制备的石墨烯溶在无水乙醇中,在大功率超声搅拌下形成均匀的石墨烯分散液,然后把NCA8155粉末加入上述溶液中,将混合物轻微超声搅拌自组装,透析㊁干燥后得到G-NCA8155㊂石墨烯三维网络增加了材料的比表面积,同时协同效应能够提高电子导电性和稳定晶体结构,从而显著提高倍率性能和循环稳定性㊂Tian等[26]通过共沉淀和水热反应制备了一种具有独特结构的三维多孔石墨烯气凝胶包裹的NCM622纳米颗粒(NCM@GA)㊂由于其高导电性和大量相互交织的开放孔结构,自组装后的石墨烯气凝胶网络可以极大地加快电子和离子的传输速率,提升电化学反应动力学㊂此外,分散良好的NCM622纳米颗粒可以提供更大的电极-电解质界面并促进Li+的快速传输㊂因此,三维导电结构和分散良好的纳米粒子的协同作用可以有效地增强NCM@GA材料的电化学性能㊂Liu等[27]用蔗糖和葡萄糖作为碳料,在NCA8155表面构建纳米碳包覆层㊂结果表明,以蔗糖为碳源构建的包覆层具有更好的电化学性能㊂原因是葡萄糖碳化后形成的包覆层较致密,而蔗糖形成的包覆层相对疏松,内部分布着尺寸较大的孔结构㊂这样的碳包覆层具有较大的比表面积,有利于电解液的浸润,同时也有利于Li+的脱嵌和迁移,并能减缓电解液对本体材料的侵蚀㊂Cao等[28]制备了集聚苯胺(PANI)优异的电子导电性和聚乙二醇(PEG)的高离子导电性于一体的双功能导电聚合物,用于NCM811材料的表面改性,获得高性能NCM@PANI-PEG复合材料㊂具有高弹性和高柔韧性的PANI-PEG聚合物在减轻循环过程中NCM811材料的体积收缩和膨胀方面发挥着至关重要的作用㊂过渡金属的溶解是由电解液分解产生的HF腐蚀引起的,这会对电化学性能产生不利的影响㊂在相同的储存时间下,表面改性电极中Ni㊁Co和Mn过渡金属的溶解量均低于未修饰的电极㊂包覆到NCM811颗粒表面的PANI-PEG保护层提供了物理屏障,以防止正极材料被HF侵蚀,从而抑制过渡金属的溶解,进而提高主体材料在高温下的循环稳定性㊂苝-3,4,9,10-四羧酸二酐(PTCDA)是一种具有高化学稳定性的N型有机半导体材料㊂PTCDA的高电子亲和力(约3.6eV)导致附加负电荷更容易稳定化,为黏附石墨烯提供了理论基础㊂从结构上看,PTCDA分子为二维共轭π电子体系,其所携带的苯环与石墨烯的六方结构是一致的㊂Ning等[29]在PTCDA的作用下,通过简单的物理混合来制备均匀的rGO包覆的NCM811(PG-NCM)材料㊂在使用PG-NCM作为正极材料时,rGO纳米片和PTCDA的协同作用可以提供更好的电子导电性和更稳定的电极-电解质界面㊂特别是P1G1-NCM(仅含质量分数1.0%的添加剂)在所有样品中表现最佳,在1C 倍率下达到了194.1mAh㊃g-1的放电比容量,在循环100次后容量保持率为92.8%,并且在高倍率下性能也得到了提升(10C倍率下放电比容量达到122.1mAh㊃g-1)㊂3㊀复合包覆材料3.1㊀电子电导性材料和金属氧化物复合包覆通过电子电导性材料和金属氧化物复合包覆层可以同时改善正极材料的导电性和结构稳定性㊂在这种方法中,其中一种成分可以通过保护表面免受不需要的副反应来提高循环性能,而另一种成分则提升了电子导电性能,提高了放电比容量㊂Y2O3作为包覆剂,使用石墨烯作为导电添加剂㊂Y2O3属于稀土元素氧化物,具有很高的热稳定性㊂Loghavi等[30]通过湿法化学煅烧的方法用Y2O354郑州大学学报(理学版)第56卷修饰NCA811正极材料,并将制备的材料与石墨烯机械混合㊂电化学性能测试表明,NCA811㊁Y 2O 3/NCA811和石墨烯/Y 2O 3/NCA811材料在2C 倍率下分别提供109㊁136和164mAh ㊃g -1的放电比容量㊂石墨烯/Y 2O 3/NCA811材料在100次循环后(0.5C)依旧拥有180mAh㊃g-1的放电比容量,而原始NCA811仅提供了87mAh ㊃g -1的放电比容量㊂3.2㊀离子电导性和电子电导性材料复合包覆在材料表面构建一种具有高离子和电子导电性的双功能包覆层,可以提高电池在循环过程和离子储存过程中的稳定性㊂本体材料㊁离子包覆材料㊁电子包覆材料和电解质共同形成了四相正极-电解质界面,这对容量保持率的大幅度提高起到了关键作用㊂Yang 等[31]在NCM811表面构建了具有高离子和电子电导率的多功能包覆层,以提高电池在循环过程中的稳定性㊂磷酸与原始NCM811上残留的锂盐发生反应,形成具有碳纳米管穿透的Li 3PO 4包覆层,具有高离子和电子导电性㊂NCM811㊁Li 3PO 4㊁CNT 和电解质共同形成四相正极-电解质界面,这对提高容量保持率起到关键作用,在0.5C 倍率下循环500次后,容量保持率从原始的50.3%提高到84.8%㊂改进后的NCM811在高截止电压4.5V㊁高温55ħ和10C 倍率下依旧具有出色的电化学性能㊂此外,在高湿度空气中暴露2周后,它还可以在500次循环后提供154.2mAh㊃g -1的放电比容量㊂CNT-LPO-NCM 的机理示意图和循环性能如图3所示㊂图3㊀CNT-LPO-NCM 的机理示意图和循环性能[31]Figure 3㊀Schematic diagram of mechanism and cycling performance of CNT-LPO-NCM [31]为了提高锂离子电池正极材料的离子和电子导电性,Na 等[32]提出一种具有高离子导体Li 1.3Al 0.3Ti 1.7[PO 4]3(LATP )和高电子导体多壁碳纳米管的Li 1.03(Ni 0.88Co 0.08Mn 0.04)O 2正极材料的表面改性,LATP 粉末使用改进的Pechini 方法制备而成㊂表面改性的高镍NCM 电极,其表面高离子和电子导电网络能够实现Li +和电子的快速传输,从而显著增强充放电循环期间的电化学性能㊂3.3㊀离子电导性材料和金属氧化物复合包覆金属氧化物可以保护材料免受电解液的侵蚀,金属氧化物包覆层可以提高材料界面结构的稳定性,提升电池的循环性能㊂离子电导性材料包覆层可以增强Li +的传输能力,提高电池的倍率性能㊂离子电导性材料和金属氧化物复合包覆层可以同时提高电池的容量保持率和倍率性能㊂Maiti 等[33]采用了一种简单有效的ALD 包覆策略,用Al 2O 3㊁Li 5AlO 4和Na 5AlO 4对NCM424粉末材料进行表面包覆,从而提高了其氧化还原活性,抑制不可逆的氧从晶格中释放出来㊂在1C 倍率下超过400次循环后,未包覆的NCM424材料的放电比容量仅有63mAh ㊃g -1,而具有复合包覆层的NCM424材料显示出大约两倍的放电比容量㊂通过XPS 光谱和电压分布进行分析,得出了改性后的NCM424材料的表面锰从四价态部分还原到较低的价态㊂根据研究结果,在有ALD 包覆层的情况下,表面锰的还原可能是由于三甲基铝挥发性物质通过其在正极材料表面的分解反应与它们接触而发生的㊂这项工作的关键发现是,与所有包覆的正极材料相比,通过阳离子氧化(Ni 2+/Ni 4+,Co 3+/Co 4+)传递的电荷容量和经过阴离子氧化证实的电荷容量均略低于未包覆材料㊂该发现可能与NCM424颗粒表面包覆层上形成的修饰电极-电解质界面有关㊂4㊀结语高镍三元正极材料因其具有高能量密度而备受科研人员关注㊂然而,这些材料存在着一系列问题,如对空气敏感㊁与电解液反应㊁阳离子混排㊁晶格氧析出㊁过渡金属离子迁出以及微裂纹形成等,这些问题限制了高镍三元正极材料的应用与发展㊂包覆是高镍三元正极材料表面改性的重要方法㊂常用的包覆材料有电化学惰性材料㊁离子电导性材料㊁电子电导性材料㊂在此基础上发展到复合包覆,常见的复合包覆有电子电导性材料和金属氧化物复合包覆㊁离子电导性和电子电导性材料复合包覆㊁离子电导性材料和金属氧化物复合包覆㊂包覆材料不仅可以保护材料表面和提高材料的结构稳定性,还可以提高离子或电子的传输能力,提高材料的电化学性能㊂64。
Summary and Improvement of Interaction in High Sch
Background
With the increasing importance of English language skills in today's globalized world, it is critical for high school students to develop strong communication abilities However, traditional teaching methods often focus on rote learning and grammar rules, focusing on the importance of interactive and communicative language practices
Low student engagement and lake of initiative
Passive learning attribute
Some students tend to be passive in class, waiting for the teacher to provide answers or directions instead of actively participating in interactions
Lack of motivation
Students may lack motivation to participate in classroom interactions due to various reasons, such as a lack of interest in the topic, fear of making misses, or a perception that the activity is not relevant to their learning goals
铁素体不锈钢晶间腐蚀的机理和改善应用研究
MANUFACTURING AND PROCESS | 制造与工艺 时代汽车 铁素体不锈钢晶间腐蚀的机理和改善应用研究胡海波 汤旭炎无锡晶晟科技股份有限公司 江苏省无锡市 214028摘 要： 铁素体不锈钢在汽车行业使用很广泛，从电子零件到车身焊接，都要用到铁素体不锈钢，而且激光焊接是汽车系统对不同金属材料连接的一个重要方式，而不锈钢的成分对金属焊接造成的晶间腐蚀敏感性不同。
不锈钢的晶间腐蚀对焊接强度的耐久性有直接影响，对焊接牢固的安全性即对汽车系统的安全性有直接影响。
晶间腐蚀在不锈钢焊接工艺多少存在，本文对晶间腐蚀的发生原因和改善对策做了充分阐述。
关键词：晶间腐蚀 敏化作用 贫铬区 铬化物 草酸试验法1 引言汽车电子零件和钣金件，有用到很多铁素体不锈钢零件，而连接不锈钢的方式很多是采用激光焊接工艺，激光焊接后强度能满足测试要求，但是在长期的盐雾试验后，我们发现有很多发生了晶间腐蚀，造成焊接区域产生裂缝，甚至长期使用后，焊接部分发生脱离，造成汽车零件失效甚至造成汽车安全事故。
因此分析晶间腐蚀的发生机理和如何避免晶间腐蚀的发生尤为关键，本论文就以上问题做出深刻分析和改善措施验证，并且以汽车零件实例进行阐述。
1.1 晶间腐蚀概述晶间腐蚀指的是不锈钢在腐蚀介质的作用之下在晶粒之间所产生的一种腐蚀现象。
晶间腐蚀是一种局部腐蚀，这种腐蚀会沿着金属晶粒间的分界面向内部扩展，其会严重破坏晶粒间的结合力。
导致这种腐蚀现象发生的原因是晶粒表面和内部之间的化学成分有着较大的差异，并且有晶界杂质或者是内应力存在。
这种腐蚀会严重破坏晶粒间的结合，让金属的机械强度受到巨大的影响。
需要注意的是这种腐蚀在金属和合金的表面看不出有破坏的迹象，然而其内部晶粒之间的结合力已经被破坏，并且力学性能也出现了恶化，很难有效分辨，所以非常危险。
只有采用金相显微镜进行观察，才能够发现晶界呈网状形态，晶界区因腐蚀已遭破坏，晶粒也接近分离。
晶间腐蚀多出现于黄铜、硬铝合金以及一些不锈钢、镍铬基合金中。
地质学专业英语I
inclined bed 倾斜层
inclined boring 倾斜钻进
inclined drilling 倾斜钻进
inclined fold 歪斜褶皱
inclined plane 倾斜面
inclined seam 斜矿层
inclined shaft 斜井
impervious bed 不透水层
impervious horizon 不透水层
impervious lens 不渗透透镜体
impervious stratum 不透水层
imperviousness 不渗透性
implement 执行
implicated structure 显微共生构造
infrared detector 红外探测器
infrared photography 红外摄影
infrared radiation 红外线辐射
infrared rays survey 红外线甸
infrared remote sensing 红外遥感
infrared spectroscopic analysis 红外光谱分析
industrial water 工业水
inelastic collision 非弹性碰撞
inert components 惰性组分
inert gas 惰性气
inert gas elements 惰性气体元素
inertinite 惰性煤素质
inesite 红硅钙锰矿
infancy 幼年
inclined slice 倾斜分层
inclinometer 井斜仪
inclusion 包体
环形束激光熔覆CuPb10Sn10_减摩涂层组织性能调控
表面技术第52卷第7期激光表面改性技术环形束激光熔覆CuPb10Sn10减摩涂层组织性能调控程梦颖a，石拓b，万乐a，魏超a，张荣伟a，蔡家轩a，袁德涛a （苏州大学 a.机电工程学院 b.光电科学与工程学院，江苏 苏州 215000）摘要：目的为了从原理上改良汽车关键零部件特定表面的减摩性能，提出环形激光熔覆高质量CuPb10Sn10铜合金异质涂层提升零部件耐磨减摩性能的方法。
方法设计单层熔覆、顶部重熔、逐层重熔3种制备方案，采用环形束激光熔覆技术在42CrMo钢表面制备熔覆层。
分析试样的表面形貌、孔隙率、物相构成，并分析熔覆层–基材的结合强度及耐磨减摩效果。
结果基于环形激光熔覆单层熔覆层设计的逐层重熔和顶部重熔制备工艺方法均能在42CrMo钢表面实现厚1 mm减摩涂层的成功制备。
单层熔覆在熔覆过程及环境参数改变范围内的质量提升效果有限，缺陷分布明显且难以控制；顶部重熔过程中热量分布特征导致的Marangoni效应未使熔覆质量实现有效优化，熔覆层内部孔洞、裂纹、热影响区（HAZ）等缺陷未显著减少；逐层重熔法制备的熔覆层质量大幅提升，制备过程显微组织变化过程为：不均匀网状分布–独立棒状分布–“芝麻”状分布，且发现“芝麻”状分布SPP（富铅第二相粒子）的减摩效果优于独立棒状分布SPP。
熔覆层出现偏析分层，且凝固过程晶粒长大生成柱状枝晶。
逐层重熔法制备的CuPb10Sn10熔覆层孔隙率不高于0.5%，摩擦因数较原始基材表面下降量可达75%。
结论实现了碳钢材料零部件表面高性能耐磨减摩涂层的成功制备，为汽车制造等工业零部件设计与生产提供了新的思路及工艺理论指导。
关键词：环形束激光；CuPb10Sn10；异质结合；显微组织；耐磨性能；减摩性能中图分类号：TN249文献标识码：A 文章编号：1001-3660(2023)07-0336-12DOI：10.16490/ki.issn.1001-3660.2023.07.031Performance Regulation of Annular Laser Cladding CuPb10Sn10Anti-friction Coating MicrostructureCHENG Meng-ying a, SHI Tuo b, WAN Le a,WEI Chao a, ZHANG Rong-wei a, CAI Jia-xuan a, YUAN De-tao a收稿日期：2022–06–14；修订日期：2022–10–25Received：2022-06-14；Revised：2022-10-25基金项目：国家自然科学基金（62173239）Fund：National Natural Science Foundation of China (62173239)作者简介：程梦颖（1998—），女，硕士生，主要研究方向为激光增材制造。
英汉词汇对照
英汉词汇对照“ A ” segregates in steel in got钢锭中的“ A ” 型偏析Acetylene :carburizer乙炔渗碳剂soot乙炔烟Aggregate moulds聚合物铸型Aerofoil fluidity test 螺旋桨桨叶流动性测试Aerospace casti ng reliability航天用铸件的可靠性Air bubbles 气泡Air gap 气隙Al in cast iron 铸铁中的铝A1-Bi alloy 铝铋合金Al-Cu alloy 铝铜合金Al-Cu-Ag alloy 铝铜银合金Al-Cu-X alloys 铝铜-X 合金Al-Mg alloys 铝镁合金Al-Pb alloys 铝铅合金Al-Si alloys : 铝硅合金high Si wear resista nt高硅耐磨铝硅合金mecha ni cal properties铝硅合金的力学性能porosity 铝硅合金的疏松Al-Sn alloys 铝锡合金Al-Zn superplastic alloys 铝锌超塑性合金Aluminium bronze 铝青铜Aluminium powder mould wash 铝粉铸型涂料AIN 氮化铝Ammonium bifluoride 氟化氢铵Anodizing 阳极处理Argon : 氩气degass ing氩气除气in pores气孔中的氩气Auste nite奥氏体Bala need steels半镇静钢Be effect on oxide film 对氧化膜的影响Be nd test弯曲试验Ben to nite 膨润土Benzene苯Bessemer con verte贝氏转炉（酸性转炉）Bifilm, see also films : 双层膜（参见膜）asymmetric双层膜的不对称性buoya ncy双层膜的浮力characteristic appeara nc双层膜的外貌特征deactivation 双层膜失去活性definition 双层膜的定义n etworks网状双层膜Bimodal distribution 双峰式分布Binders for sand : 型砂黏结剂breakdow n, see Furan型砂黏结剂溃散（见呋喃）water con te nt型砂黏结剂的水含量Bismuth 铋Blast furnace 鼓风炉Blow defect 砂芯侵入性气孔缺陷Body cen tred cubic 体心立方Boiling points : 沸点brasses黄铜的沸点liquid metals 液态金属的沸点Boron 硼Boun dary layer 边界层Bran ched colu mnar zone in steel in got连冈锭中的分枝柱状晶区Brasses黄铜Breakdow n of sand bin ders after casti n篩造后砂黏结剂破裂Brittle failure 脆性断裂Bron zes 青铜Bobble: 气泡trail 气泡轨迹damage气泡损伤collapse气泡塌陷Camber挠度Capillary repulsion 毛细排斥Carbon boil 碳沸腾Carbon-based moulds碳基铸型Carbon equivalent value（ CEV）碳当量Carburization 渗碳Cast iron : 铸铁ductile 球墨铸铁grey(flake) 灰铸铁growth 铸铁晶粒生长internal oxidation 铸铁内部氧化sectio n size effect铸铁断面尺寸效应volume cha nge铸铁体积变化white 白口铁Cavitatio n damage 空蚀损伤Cells, cellular growth 晶胞，胞状生长C.ha nnel defects通道缺陷Channel segregate!道偏析Charcoal 木炭Charge materials炉料Chills 冷铁Chromite glaze 铬铁釉料Chvorinov Chvorinov 定律／平方根定理Closed crack闭合裂纹Coal additive 煤粉添加剂Coarse ning of den drite arms枝晶臂粗化Coat ings on chills 冷铁涂料Cobalt alumi nate 铝酸钻Cobalt-base casti ng alloys钴基铸造合金COD(Crack Ope ning Displaceme nt) tes裂纹展开位移试验Cold lap 冷搭接缺陷Cold shut, see Cold lap冷隔缺陷Columnar grain 柱状晶粒Computer discs计算机硬盘Conden satio n on chills 冷铁上凝结Conden sati on zone凝结区域Conden sed phase 凝结相Co nflue nee weld 汇流焊缝Constitutional undercooling 成分过冷Con ti nu ous cast ing 连续铸造Continuous fluidity 连续流动性Convection : 对流in casti ngs铸件中的对流in moulds 铸型中的对流Cope heati ng上型(砂)箱加热Coring 芯子Corrosion 腐蚀filiform 丝状腐蚀intergranular 晶间腐蚀pitting 点蚀Cosworth Process Cosworth消肖除热疲劳裂纹工艺Counter gravity casting 反重力铸造Crack blunting 裂纹钝化Crankshafts in ductile iron 球铁曲轴Creep蠕变Cristobalite 方石英Criteria functions 判据函数Critical fall height 临界下落高度Critical flaw size 临界裂纹尺寸Critical velocity 临界速度Croning shell moulds克郎宁壳形铸型Cryoge nic treatme nt for stress relie释放应力的低温处理Crystal structure of metals : 金属晶体结构steels cubic lattices!冈的立方晶格Hall-Petch resistance to slip Hall-Petch 滑移阻力hexagonal close packed lattice （Mg）密排六方晶格（Mg） lattice definition 晶格定义Cupola for iron melting 铸铁熔炼冲天炉Cu alloys porosity铜合金的疏松缺陷Cu-Zn-Al alloy 铜锌铝合金Cyli nder heads 气缸盖Dampi ng capacity, see In ternal frictio n 阻尼性能（见内部摩擦）DC casting , see Continuous casting 直接激冷铸造（见连续铸造）Deactivation , see Bifilms 失去活性（见双层膜）Decarburization 脱碳Deep draw ing steel 深冲钢Degass ing 除气Dendrite arm spacing（DAS）枝晶臂间距Den dritic segregati on 枝晶间偏析Density index 密度指数Deoxidation : 脱氧copper alloys铜合金脱氧steels , see Steel钢脱氧（见钢）Detrain 卷出／卷入到金属液的表面膜再次返回到表面上Diamond films 金刚石薄膜Die cast ing, see Pressure die casting 铸（见压力铸造）Diffraction mottle 衍射斑点Diffusion 扩散Diffusion bonding 扩散黏结Dihedral an gle 二面角Direct chiII（DC） cast ing see contin uous cast ing直接激冷铸造（见连续铸造）Distortion 扭曲Dog bo ne hot tear tests I杆形热撕裂试验Drag coefficient 阻力系数／牵引系数Draw, see Porosity surface ini tiatec裂纹（见始于表面的疏松）Dross熔渣Dross stri ngers in ductile irons球铁抛光断口上“渣线”缺陷，实为卷入的膜Ductile iron, see also Spheroidal graphite iron球铁（见球墨铸铁）Ductility 延展性Dye pen etra nt testi ng着色探伤Elastic modulus , see Young ' s modulus 弹性模量（见杨氏模量）Electro-slag casti ng 电渣熔铸Ellingham diagram Ellingham 图（氧化物标准生成自由能与温度关系图）Elongation, see Ductility 延伸率（见延展性）Entrained bubbles卷入的气泡Entrainment definition “卷入”定义En vir onment 环境Equiaxed grain 等轴晶Eutectic reduc ing porosity共晶减少疏松缺陷Eutectic reduci ng hot teari ng共晶减少热撕裂缺陷Exfoliation defect 鳞型剥落缺陷Extreme value distribution 极值分布Face cen tred cubic面心立方Fatigue : 疲劳high cycle,low stress高周低应力疲劳high stress,low cycle高应力低周疲劳improvement by HIPping 热等静压改善疲劳pull-pull versus push-pull 拉一拉与压一拉式疲劳thermal 热疲劳Favalite铁橄榄石Feather den drite羽状枝晶Fe-C alloys铁碳合金Feed mecha nism# 卜缩机希9Feed paths# 缩通道Feed ing Rules补缩准则Ferro-chrome 铁铬Ferro-ma ngan ese铁锰Fillability 充型能力Film.see also Bifilms 膜（见双层膜）A12O3 三氧化二铝膜AIN 氮化铝膜graphitic 石墨膜liquid 液膜new and old新膜和旧膜stre ngth膜强度structure膜结构TiN 氮化钛膜transient films 瞬态膜Filtration 过滤Fins铸件飞边Flash喷溅，飞溅Flowability 流动能力Fluidity 流动性Flux treatme nt 熔剂处理Foil stock 金属箔原料Fold defects in lost foam cast ing消失模铸造中的折叠缺陷Fracture mecha nics断裂力学Fracture tough ness断裂韧性Freckle defects “斑点”缺陷Friction betwee n casti ng and mould铸件与铸型的摩擦Froude number弗鲁德数Fules燃料Furan , furane呋喃Furling （and unfurling）卷起（和展开）Furn ace types炉子类型Galvanising （hot dip）电镀（热浸）Gamma distribution 伽马分布（用于描述延展性失效）Gasses : 气体in Cu alloys 铜合金中的气体in Fe alloys 铁合金中的气体Gas law 气体定律Gaussian 高斯型分布（有关材料强度，图9.24）Glass 玻璃Glissile drop 滑动液滴／滑移液滴Grain boundary：晶粒边界decohesion 晶界分离migration 晶界迁移sliding 晶粒滑移Grain growth 晶粒生长Grain refinement：晶粒细化advantages 晶粒细化的优点aiding hot tear growth 晶粒细化促进热撕裂生长aiding mass feeding 晶粒细化促进浆态补缩by fragmentation/multiplication 通过枝晶分裂／增殖细化晶粒by nucleation 通过形核细化晶粒reducing strainconcentration 细化晶粒减少应变集中Grain structure in castings 铸件中的晶粒结构Graphite dies 石墨模具Graphite film 石墨膜Graphite nodules, see Spheroidal graphite; Ductile ironGraphite die casti ng dies石墨球（见球形石墨，压铸模具中球形石墨）Gravity segregati on 比重偏析Great Paul Bell伦敦圣保罗教堂大钟Grey cast iron 灰铸铁Growth restrictio n parameter生长限制参数Gumbel distribution Gumbel 分布（最大极值分布，用于分析某领域最多缺陷的概率）Hall-Petch equation Hall-Petch方程（晶粒尺寸减小，屈服强度增大方程）Heat transfer coefficie nt 换热系数Heat treatme nt reducti on of ten sile propertie降低拉伸性能的热处理Hexachloretha ne mould coat六氯乙烷铸型涂料High pressure die casti ng, see Pressure die casti n高压铸造（见压铸件）Hippi ng see Hot Isostatic Press ing热等静压处理（见热等静压）Homogenization 均质化Hot Isostatic Press ing 热等静压Hot spot （promoting tearing）热节（促进撕裂）Hot teari ng 热撕裂Hot tearing susceptibility 热撕裂敏感性Humidity 湿度Hydraulic radius 水力半径Hydraulic jump 水跃／金属液面翻腾Hydrogen : 氢embrittleme nt in steels 钢中的氢脆equilibration with environment 与环境中的氢相平衡in solution in Al 在铝中溶解的氢in solution in Cu 在铜中溶解的氢pick up from moisture 从湿气中获得的氢permeati on渗氢（渗入的氢）Hydrocarbon fuels碳氢化合物燃料Hydrostatic （triaxial） stress 静水（三轴）应力Ice 冰Impregnation 浸渗Inclusions , see Non-metallic inclusions 夹杂物（见非金属夹杂物）Inert gas solubility 惰性气体的溶解度In gots and in got moulds, see also Rimi ng steel 钢锭和钢锭模（见沸腾钢）Inhibitors ~抑制剂Ino culatio n of cast irons 铸铁的孕育处理Inserts 内冷铁Interdendritic : 枝晶间feedi ng枝晶间补缩flow 枝晶间流动In termetallic compo unds 金属间化合物Internal oxidation 内部氧化In verse chill in cast irons铸铁中的“逆向激冷”现象Inverse segregation, see Dendritic segregatio逆偏析”（见枝晶偏析），是过去对“枝晶偏析”的错误叫法Investment : 精密铸造casti ng精密铸造mould 精密铸造蜡模铸型lron carbonyl 羰基铁Iron oxide addition to sand bi nders向型砂黏合剂中添加的氧化铁Killed steel 脱氧钢，镇静钢Laminar flow 层流Lap defects: 搭接缺陷cold lap 冷搭接缺陷confluence weld 汇流焊缝缺陷oxide lap 氧化物搭接缺陷Lattice, see Crystal structure晶格（见晶体结构）Lead-a ntim ony alloys 铅锑合金Lead in Cu alloys铜合金中的铅Leak detection 渗漏检测Leak sealing , see Impregnation 渗漏密封（见浸渗）Leak tight ness渗漏气密性Liberty Bell, USA 美国自由大钟LIMCA 监控铝合金液夹杂数量测试技术Liquid metal in ternal structure 液态金属的内部结构Lost foam casti ngs 消失模铸造Lost wax castings , see , Investment castings失蜡铸造法（见精密铸造法）Low pressure casti ng｛氐压铸造Lustrous carb on 光亮碳Machining 机加工allowa nee力卩工余量carbide and diam ond cutti ng tools硬质合金和金刚石刀具machi ne tool beds机床床身machinability 机械加工性，切削性mach ined surfaces 机加工的表面Magnesium : 镁vapour镁蒸汽burning , oxidation 镁燃烧，镁氧化Manifold casting 进气歧管铸件Marangoni effect Marangoni 效应（氐表面张力的液体在表面上向高表面张力的液体处流动现象）Mass feedi ng浆态补缩Meni scus adva nee without en trai nmen没有卷入现象的弯月面推进Metal/matrix composite （MMC）金属基复合材料fluidity 金属基复合材料流动性vortex method 涡流法制备金属基复合材料Mg-Zn alloys 镁锌合金Mg-Zr alloys 镁锆合金Mircroblows 微观侵入性气孔Microjetting 微型射流Misrun 浇不足MnS in steels钢中的硫化锰Modulus （geometric）模数（几何的）effect on fluidity 模数对流动性的影响effect on que nching stresS模数对淬火应力的影响Mould : 铸型dilation 铸型膨胀dress ing or coati ng 铸型涂料gasses铸型气体gen eral铸型总体介绍pe netration铸型的渗透Negative segregation负偏析NDT, see non-destructive test ing无损检测Nickel-base cast ing alloys 镍基铸造合金Nitride films 氮化物膜Nitrogen: 氮protective bla nket 氮气保护层in soluti on in iron and steel 钢铁中溶解的氮Nitroge n fissures in cast iron 铸铁中氮裂纹Nodular graphite, see ductile iron; and spheroidal graphite 石墨球（见球墨铸铁和球形石墨）Non destructive testi ng 无损检测Non-metallic inclusion 非金属夹杂物action of entrained particles as pores卷入的夹杂物粒子作用如同气孔作用（对材料延展性的危害）agglomerati on夹杂物团聚clumping 夹杂物聚集distribution in steel ingot 夹杂物在钢锭中的分布flocs and flocculation 絮凝夹杂物growth 夹杂物生长in Al alloys 在铝合金中的夹杂物in cast steels在铸钢中的夹杂物in rolled steels在轧钢中的夹杂物macroin clusi ons 宏观夹杂sand in clusi ons 夹砂shape con trol夹杂物的形状控制sulphides in steels!冈中的硫化物夹杂types夹杂物类型Normal distribution 正态分布Nucleation : 形核auste nite奥氏体形核control by [O] in Fe and Cu 铁和铜中由氧原子控制的形核diagram 形核相图graphite石墨形核general —般形核in clusi on and sec ond phase夹杂物与第二相形核pores and cracks气孔与裂纹的形核shri nkage pores收缩孔隙的形核steel钢的形核Oil can distortion 油罐扭曲Oil pan casti ng, see Sump cast ing由盘铸件（见油盘铸造）Olivine 橄榄石Oxidation : 氧化rate 氧化速率Mg burni ng example镁燃烧氧化实例Oxide flow tube defect氧化物流管缺陷Oxide lap 氧化物皱皮Oxyge n steelmaki ng 氧化法炼钢Pai nt涂料Partition coefficient 分配系数Pasty freezi ng 糊状凝固Patter nm aker' s shri nkage allowa nc模型工的收缩余量Perma nent mould casti ng, see Gravity die casti n永久型铸造，见金属型铸造Phosphoric acid 磷酸Phosphorus : 磷in Al-Si 铝硅合金中的磷in grey iron 灰铸铁中的磷in steels钢中的磷Plate fracture in ductile irons球墨铸铁中的板状裂纹PODFA 铝液通过细小过滤器收集夹杂物测试其数量Polymer que ncha n聚合物淬火介质Porosity : 气孔或疏松blow defects侵入气孔缺陷En trai ned air bubbles卷入气泡External, see Surface ini tiatec表层疏松（见始于表面的疏松）Gas porosity types气孔类型Grain refin eme nt effect晶粒细化减少疏松Growth domination by [H] [H] 控制气孔生长Layer porosity 层状疏松Layer porosity con trasted with hot teari ng 与热裂相对应的层状疏松Maximum pore size最大气孔尺寸Microporosity and macroporosity 微观疏松和宏观疏松Nucleation 气孔形核Origins 气孔源Reduction by eutectic 共晶减少疏松Secondary pore匸次缩孑LShrin kage porosity 疏松Surface in ititates/co nn ectec皮下萌生气孔/与表面连通气孔Wormhole type蠕虫状气孔Porosity test: 疏松测试Cast ing test铸件疏松测试Porotec test, see also RP减压疏松测试Wait and see Tes等和看疏松测试Potassium borofluoride 氟硼酸钾Powder coati ng粉末涂料PREFIL 铝液通过细小过滤器收集夹杂物测试其数量Pressure applied in casti ng施加在铸件中的压力Pressure die cast ing$铸Dies压铸模Lubricant/cooling 压铸润滑剂/压铸冷却Pressure tight ness , see Leakage defects气密性（见渗漏缺陷）Proof stre ngth, see Yield stre ngtlh单性极限强度，屈服强度Pyrolysis 高温分解Quality assura nee质量保证Quartz石英Que nch distortion 淬火扭曲Quench factor an alysis淬火因素分析Quench stress, see also Residual stre淬;火应力（见残余应力）Que nchants淬火介质Radioactivity 放射性Radiography , see X-ray radiography 射线检验学（见X 射线照相术）Rare earth 稀土Recrystallization 再结晶Reduced pressure tes减压测试Reliability of castings 铸件的可靠性Remelting : 重熔of solid 固态重熔of dendrite roots 枝晶根部重熔Residual stress残余应力Reynold ' s number Re雷诺数ReRheology of the solid alloy 固态合金的流变Rigidity, see also Young ' s modulus 刚度（见杨氏模量）Rimming steel 沸腾钢Ring test for hot teari ng 环形热裂测试Rock candy fractures in steels!冈的岩石状断裂Roll-over tech nique 翻箱工艺Rolling wave 滚动波Rolling-back wave 反向滚动波Rolled steel 轧冈Rotary degass ing旋转除气RPT, see Reduced pressure te减压测试（见减压测试）Running system 浇注系统Sai nt Paul ' s Cathedral Bel伦敦圣保罗教堂大钟Sand in clusi ons 夹砂Sand moulds 砂型Sealing , see Impregnation 密封（见浸渗）Segregati on 偏析microsegregati on, see Cori ng显微偏析（见制芯）segregati on ratio偏析率un der feeder冒口下偏析Sessile drop黏着液滴Shell moulds : 壳型铸型croning shell 克郎宁壳型inv estme nt shell 蜡模壳型Shrin kage allowa nee 收缩余量Shrin kage porosity 疏松Shrinkage porosity misidentification 疏松识别错误Si ngle crystal 单晶Sink, see also porosity surface-i nitiatec凹坑（见表面萌生气孔）Skin freezing 逐层凝固Sn-Pb alloys锡铅合金Sodium addition to Al-Si alloys 铝硅合金中的钠Soldered joint 锡焊缝Solid (self) feeding 固态(自)补缩Solution treatment 固溶处理Spheroidal (no dular) graphite 球墨铸铁Spinel 尖晶石Stai nless steels不锈钢Stars at night defects像夜空中点点繁星式的双层膜缺陷Steam reaction汽化反应Steels and steelmaking :钢和炼钢bottom-pour ( bottom-teemed) ladles 炼钢用底漏钢包copper con tami natio n钢中的铜污染deoxidation 钢脱氧embrittleme nt 钢的氢脆gases!冈中气体homoge ni zatio n钢的均质化Steels and steelmaking (cont) :钢及炼钢hot teari ng钢的热撕裂rolling cracks 钢的轧制裂纹Strain concen trati on 应变集中Statistics 统计Straube-Pfeiffer test, see RPT Straube-Pfeiffer 测试(见减压测试)Stress concen tratior应力集中Stress corrosi on cracki ng应力腐蚀裂纹Stress inten sity factor 应力强度因子Stress relief, stress relaxation应力释放Strontium addition to Al-Si alloy 向铝硅合金中加入的锶添加剂Subgra in boun daries亚晶界Suboxides低价氧化物Subsurface porosity皮下气孑Lcasti ng test铸件测试皮下气孔wait and see Tes等和看测试皮下气孔Sulphide in clusio ns in steels^ 冈中的硫化物夹杂Sulphur 硫Sulphur hexafluoride 六氟化硫Sulph onic acid 磺酸Sulphuric acid 硫酸Sump cast ing油盘铸件Superheat defi niti on 过热定义Superplastic 超塑性Supply chain 供应链Surface in itiated/c onn ected porosity表面萌生疏松/与表面连通的疏松Surface in itiated crack colours in steels!冈表面萌生裂纹的颜色Surface in itiated tears皮下萌生裂纹Surface curvature表面曲率Surface fin ish/sk in of cast ing 铸件的表面清理Surface reactio n 表面反应Surface tension: 表面张力explanatory definition 表面张力的定义curvature fun ction表面张力的曲率方程plus surface film complication 表面张力和表面膜的复合影响更复杂Surface turbule nee defi niti on 表面湍流定义Swell 膨胀Tay Bridge Disaste r (英国苏格兰中部)泰河桥灾难Tellurium 碲(Te)Temper colours for steels!冈的回火颜色Temperature gradient :温度梯度in casti ng铸件中的温度梯度at freezi ng front凝固前沿的温度梯度Ti alloys 钛合金TiC 碳化钛TiN 氮化钛Tilt casting 倾斜铸造Tin sweat in bron zes青铜中的锡汗Thermal an alysis 热分析Thermal fatigue : 热疲劳of dies模具的热疲劳of casti ngs铸件的热疲劳Thermal tran spiratio n 热蒸发Three poi nt bend test三点弯曲测试Tool steels 工具钢Tough ness韧性Tramp eleme nts in steel^冈中的残余元素Tran sformatio n zones转化区域Tridymite 鳞石英TRIP (Transformation Induced Plasticity) 相变诱导塑性Turbi ne blades, see also Ni-base allo涡轮叶片(见镍基合金) Turbulence : 湍流bulk 整个体积内湍流surface表面湍流Type metal铅字金属Ultimate ten sile stre ngth 抗拉强度Ultraso nic fatigui ng of surface defect 表面缺陷超声波疲劳探测Ultrasonic testing : 超声波检测of liquid metals 液态金属的超声波检测of railroad wheels铁路车轮超声波检测Unfurling 展平Unit cell 单个晶胞Unzipping wave 链开波'V' segregation in steel ingots!冈锭中的V 型偏析Vacuum arc remelt ing真空电弧熔炼Vacuum casti ng真空铸造Vacuum degass ing真空除气Venting 排气Vibration 振动Viscosity 黏度VK Strip Test VK 带形测试Vortex method for MMC production 用于金属基复合材料生产的涡流法Waterfall effect 瀑布效应Weber Number We韦伯数Weibull modulus 威布尔模数Welds, weldi ng 焊接Wetting: 润湿adhesio n润湿黏附definition 润湿定义non-wett ing and de-wett ing 不润湿of grain boun daries 晶界润湿of moulds 铸型润湿Wheels : 轮Al alloy 铝合金轮毂steel rail tappi ng钢轨轮敲击检测轮上是否有裂纹White iron, see cast iron 白口铁（见铸铁）Work harde ning 加工硬化Wrought alloys 锻造合金Wustite FeO 方铁矿石（FeO）X-ray radiography standards X 射线成像标准Yield strength 屈服强度Young ' s modulus 杨氏模量Yttria 氧化钇Zildjian cymbals 生产钗鲅Zildjian 公司Zinc alloys : 锌合金Gen eral普通锌合金ZA alloys ZA 系列锌合金（高铝含量锌合金，含铝8%，12%，27%）Zi nc pressure die casti ng锌压铸件Zi nc vapour, zi nc flare 锌蒸汽，锌焰Zircon : 锆mould 锆砂铸型mould coat锆英粉涂料Zirconium alloys 锆合金Zirconium addition for grain refinement 细化晶粒用锆添加剂Vocabularies in “Castings”Chapter 2 entrainment Entrain v 拖拽，吸入；坐火车，携带Entrainment n 夹杂，输运Submerge vt 淹没，沉入水中，是沉浸Buoyancy n 浮力，愉快Buoyant adj 能浮的，有浮力的Crown n 王冠，顶，头Trail n 痕迹，小径Convolute adj 回旋状的Crumple n 皱纹，v 挤皱Chlorine n 氯Chloride n 氯化物Fluorine n 氟Fluoride n 氟化物Underlie v 在,, 的下面Clump n 快v 成块，使成块Exogenous adj 外生的，外院的Envisage v 正视Envision n 预想，展望Akin adj 类似的Enfold v 包裹，拥抱Debris n 残骸，瓦砾堆Entrap v 缺陷，使陷入困难或危险Heap v 堆，大量Conical adj 圆锥的Asymmetric adj 不对称的Symmetric adj 对称的Confluence n 聚集处Confluence weld 溶合不良Dyed-in-the-wool 彻头彻尾的，纯粹的Menisars n 新月型Inconstrained 不多拘束的，自然的Aggressive adj 积极地Crease n 折痕Tangle v n 缠结，纠缠，混乱Detach v 使分开Furl v n 卷起，合拢，卷，收拢Ravel v 拆开，解除Quiescent adj 禁止的Flutten v 使平，击倒Lengthy adj 长的Pivotal adj 关键性的，重要的Deactivate v 是无效，是不混乱Spindl n 尖晶石Solder n 焊料，结合v 大旱Lustrous adj 有光泽的，灿烂的Detrain v 下火车Highlight v 强调n 最重要的部分Bear in mind Ratimale n 根本理由，理论基础Bifilm films Morass 沼泽Ricochet n 跃起v 回跳，打水漂Bounce v n 弹起，跳跃Tower 塔Shaft furnale 竖式炉Shaft n 轴，井筒Counterflow 逆流的Dry heathHearth 炉床Hearthox 炉膛Cast-in 浇入Cast-in blade 注入或叶片Inadvertent 不小心的，不注意的Overflow v 满溢Dendritic 枝状的Sump n 油井，沼泽Oil pan 油地盘Abut v 紧接，接近Intermittent adj 间接的Burst through 推开，拨开sober冷静的，镇定sundry 各式各样的hygroscopic 吸湿的dye 着色，染dye-pe netra nt crack detecti on 染色，渗透, 裂纹。
Research on the Improvement Path of the Mental Hea
Psychology Research, September 2022, Vol. 12, No. 9, 730-734doi:10.17265/2159-5542/2022.09.006Research on the Improvement Path of the Mental Health of the Elderly From the Perspective of College Students’ VolunteerService ActivitiesDONG HaojunZhaoqing University, Zhaoqing, ChinaThe elderly are the main objects of college students’ volunteer service activities. At present, there are various formsof college students’ volunteer service activities, which are highly valued by colleges and universities and popularamong college students. In order to further improve the mental health of the elderly, it could be achieved throughpaths like strengthening volunteering cooperation with aged services agencies, implementing the volunteer servicemechanism of “one person-one file, one person-one policy” for the elderly, establishing a mental health mentorsystem for volunteer service activities, improving the mental health knowledge level of college student volunteers,carrying out a series of voluntary service activities with the theme of mental health, attaching importance oncultivating the positive and optimistic attitude of the elderly in volunteer service activities, and launching volunteerservice activities to enrich the spiritual and cultural life of the elderly.Keywords: the aging of population, college students’ volunteer service activities, the elderly, mental healthIntroductionOrdinarily, a country or region can be considered to have entered an aging society when the proportion of the elderly population over 60 years old or over 65 years old in the country’s total population exceeds 10% or 7% (Wang & Wang, 2022; Wang, 2016; Zhao, 2015). In 1999, China began to enter the aging society, becoming the early group of developing countries to enter the aging society (Mu & Zhang, 2011; Xu, 2011). Faced with an aging population, it is necessary to actively solve the problems relevant to the older, like caring for the elderly, meeting the actual needs of the elderly as much as possible, managing the work of serving the elderly, improving the mental health of the elderly, and promoting the quality of life and spirituality of the elderly. Based on the author’s work experience with college students, this paper discusses how to improve the mental health of the elderly from the perspective of college students’ volunteer service activities.The Basic Situation of Our Country’s Aging SocietyAccording to the latest data from the Statistical Bulletin of the People’s Republic of China on National Economic and Social Development in 2021, the elderly population in our country has far exceeded the standard number, and is developing towards a more and more serious degree of population aging. In order to betterconduct the work of population aging, the country actively explores countermeasures, such as improving theDONG Haojun, Lecturer, Economics and Management College, Zhaoqing University, Zhaoqing, China.THE IMPROVEMENT PATH OF THE MENTAL HEALTH OF THE ELDERLY 731community home-based care environment, exploring the community home-based care model, establishing a sound social security system for the elderly, vigorously developing the aging industry, developing aging human resources, and formulating progressive formula to postpone the retirement age policy, etc.The Basic Situation of College Students’ Volunteer Service Activities The Youth Volunteer Work Department of Colleges and Universities is a college student organization engaged in the management, organization, and coordination of college student volunteer service activities under the management and guidance of the college youth league committees. Normally, the Youth Volunteer Work Department of the school sets up a secondary college branch, which is responsible for the youth volunteer activities of each secondary college, forming a management and operation model at the school and college levels. In daily work, the Youth Volunteer Work Department of Colleges and Universities organizes a series of volunteer service activities such as caring for the elderly, sanitation, and unpaid blood donation, and the elderly are the main volunteer service objects. In the specific activities of serving the elderly, it is mainly to organize college students to go to the nursing home to carry out voluntary service activities, provide loving care, emotional comfort, etc. In this way, the elderly can feel warmth, love, and kindness, which is helpful to meet their spiritual comfort and psychological need and plays a positive role in improving the quality of their life.Characteristics of College Students’ Volunteer Service ActivitiesColleges and Universities Attach Great Importance to the Work of Volunteering for the Elderly The country has always attached great importance to the elderly group, and proposed to pay more attention to the work of old-age security and strengthen the work of the elderly. It is clearly necessary to accelerate the development of the old-age service industry and the construction of the old-age service system, to build a policy system and a social environment of old-age caring, filial piety, and respecting for the elderly, to integrate medical treatment and elderly care services and to accelerate the development of aging career and industry. Correspondingly, colleges and universities also actively shoulder social responsibilities. They highly value the work of volunteering for the elderly, pull their weight on caring for the elderly, fully utilize the college students of knowledge, quality, and emotional intelligence to launch or organize volunteer service activities for college students, and guide college students to actively devote themselves to society.Colleges and Universities Regularly Carry Out Various Forms of Voluntary Service Activities The Youth Volunteer Work Department of Colleges and Universities carries out a series of volunteer activities in various forms every semester, mainly including providing volunteer services for large-scale activities inside and outside the school, carrying out service work for the creation of civilized cities, organizing volunteer education activities in primary and secondary schools, and holding activities for respecting the elderly, etc. The activities held or organized are equipped with high frequency, large number of times, and positive response. Among these activities, taking elderly service as the object of voluntary service activities can enable college students to spread civilization, convey love, perceive the world, contribute to society, enrich emotions, and enhance communication skills, which has a positive role in promoting students’ growth and success.College Students Are Keen to Participate in Volunteer Service ActivitiesCollege students are a group of ideals, goals, and vigor. They are full of social responsibility, love, and dedication, keen to participate in volunteer service activities on and off campus, being enthusiastic and having aTHE IMPROVEMENT PATH OF THE MENTAL HEALTH OF THE ELDERLY732strong volunteer spirit. College campus cultural activities are rich, and the volunteer service activities are one of the campus activities that college students like to participate in most. There are many college students applying these activities, who are passionate for participating.The Improvement Path of the Mental Health of the Elderly From the Perspective of CollegeStudents’ Volunteer Service ActivitiesStrengthen Volunteering Cooperation With Aged Services AgenciesCommunities, nursing homes, etc., are common service institutions for the elderly. They are familiar with and master the growth process, family background, hobbies, personality characteristics, mental state, and mental health of the elderly in their area. Therefore, the Youth Volunteer Work Department of Colleges and Universities should strengthen cooperation with service agencies for the elderly to ensure that the basic situation, psychological state, and practical problems of the elderly are well learned before volunteer service activities being carried out, which provides necessary help for further implementing targeted “one person, one policy” assistance and promoting the mental health of the elderly.Implement the Volunteer Service Mechanism of “One Person-One File, One Person-One Policy” for the ElderlyIt is necessary to establish a personal file of the elderly, recording the background information and psychological needs of each elderly service object in detail, the time and content of each volunteer service activity, and the changes in the elderly’s psychological state and the psychological intervention measures taken during the volunteer service activities and the psychological intervention effects, etc. All these measures are taken to ensure that psychological intervention files are recorded, psychological intervention methods are well founded, and psychological intervention effects are guaranteed. In order to provide targeted assistance for college students’ volunteer service activities, it is necessary to take the personal files of the elderly and the information provided by the elderly service agencies, etc., as reference to implement “one person, one policy” management and rationally formulate individualized mental health improvement strategies for the elderly. Establish a Mental Health Mentor System for Volunteer Service ActivitiesWith the increasing demand for services for the elderly and the complex and changeable psychology of the elderly, higher requirements are placed on the professionalism of volunteer service activities. Colleges and universities should make full use of the strong faculty of the school, establish a mental health tutor system for volunteer service activities, and hire full-time teachers with solid psychological professional knowledge, rich experience in psychological practice, and a strong sense of social responsibility as tutors to guide volunteers to master the necessary mental health knowledge and provide professional support for college students to carry out volunteer services for the elderly before, during, and after the volunteer service activities of the elderly, which helps to improve the effectiveness of volunteer service activities.Improve the Mental Health Knowledge Level of College Student VolunteersIn the past, we generally recruited college student volunteers with strong comprehensive abilities, such as strong ability, full of love, and strong willingness to serve during the process of recruiting. With the increasing attention to the mental health of the elderly, it is also necessary to consider whether college students have a professional background in psychology, whether they have certain psychological knowledge, and whether they have effective psychological intervention methods and measures when recruiting volunteers. It is essential toTHE IMPROVEMENT PATH OF THE MENTAL HEALTH OF THE ELDERLY 733reasonably recruit some college students with a professional background in psychology to participate in service activities and enrich the volunteer team. Besides, it is expected to utilize the natural advantages of the mentor system of volunteer service activities, and invite mentors to carry out special psychological training to teach psychological knowledge. And thus, volunteers can master the necessary psychological knowledge and use correct psychological intervention methods to solve problems encountered in the process of activities. Furthermore, it is support to establish an online learning platform for mental health knowledge, so that volunteers can learn psychological knowledge anytime and anywhere, and continuously improve the professionalism of the volunteer team. Finally, there is a must to establish a mental health knowledge evaluation system to check whether the volunteers’ problem-handling methods are appropriate and whether the psychological intervention methods adopted are proper, and constantly strengthen the theoretical knowledge of mental health.Carry Out a Series of Voluntary Service Activities With the Theme of Mental Health Most of the elderly have not learned psychological knowledge during their growth. When the elderly have psychological problems, they often have difficulty identifying the problem and do not know how to self-regulate. Therefore, when organizing volunteer activities for college students, it is necessary to properly guide the elderly to master the necessary mental health knowledge to promote the mental health of the elderly. For example, when colleges and universities consider the form of volunteer service activities, they can regularly carry out volunteer service activities of psychological knowledge dissemination lectures among the elderly groups, so that more elderly people can master certain psychological knowledge, learn to identify psychological problems, and learn to adjust themselves. In addition, colleges and universities can hold voluntary service activities of spiritual exchange meetings, allowing the elderly to express their inner thoughts, confusion, and expectations, understand the psychological problems of the elderly through interactive exchanges, and provide professional psychological guidance to help the elderly get rid of psychological distress. Colleges and universities can also provide voluntary psychological counseling services for the elderly, open video consultation services, and telephone consultation to solve the psychological problems of the elderly in a timely manner.Attach Importance on Cultivating the Positive and Optimistic Attitude of the Elderly in Volunteer Service ActivitiesThe mentality of the elderly directly affects their attitude, lifestyle, and mental health. When college students carry out volunteer service activities, they should establish a deep friendship with the elderly and keep contact with them. When the elderly are faced with diseases for a long time, the volunteers should pull their weight to enlighten them, encourage them to exercise properly, face up to the disease, maintain confidence, and consider the disease positively. When the elderly complain about getting old, they should actively guide them to understand aging correctly, and at the same time tell them not to be afraid of being old and keep an optimistic attitude. When the elderly complain that they are unhappy, they should chat with them more often, listen patiently, understand their inner world, and guide them to adjust their mentality and live happily.Launch Volunteer Service Activities to Enrich the Spiritual and Cultural Life of the Elderly The reasons why the elderly have low level of mental health and psychological emptiness are closely related to the lack of extensive hobbies, excess free time, and long-term alone time. When carrying out volunteer service activities for college students, it is necessary to combine the professional background andTHE IMPROVEMENT PATH OF THE MENTAL HEALTH OF THE ELDERLY734expertise of college student volunteers, and regularly hold various cultural and sports interest activities training courses among the elderly. Volunteers with sports expertise are responsible for teaching badminton, table tennis, Go, chess, etc. Volunteers with art or calligraphy majors are responsible for painting and calligraphy teaching. Volunteers with musicology background are responsible for vocal practice, breath exercise, and skill training, stage style and other teaching. Volunteers who are widely read are responsible for holding book sharing sessions. Through a series of activities, it is helpful to enrich the spiritual and cultural life of the elderly and solve the problem of mental emptiness of the elderly.ReferencesMu, G. Z., & Zhang, T. (2011). The development trend of population aging in our country and its strategic response. Journal of Central China Normal University (Humanities and Social Sciences Edition), 50(5), 29-36.Wang, S. H., & Wang, S. H. (2022). Research on the countermeasures of rural pension problems in our country under the background of population aging. Journal of Daqing Normal University, 42(1), 9-16.Wang, W. J. (2016). Research on community home-based care for the aged under the background of population aging: Taking Nanning as an example. Administration and Law, 33(10), 58-66.Xu, W. J. (2011). Research on the status quo and countermeasures of China’s population aging—Analysis based on social statistics. Oriental Enterprise Culture, 8(18), 183-184.Zhao, H. (2015). The process, current situation and countermeasures of population aging in Xingcheng City—Based on the data of the Sixth Population Census in Xingcheng City. Statistics and Management, 30(11), 81-82.。
有效应力原理的英文表述
有效应力原理的英文表述English:"The principle of effective stress, also known as the principle of effective tension or Terzaghi's principle, is a fundamental concept in geotechnical engineering and soil mechanics. It states that the total stress on a soil mass consists of two components: the effective stress and the pore water pressure. The effective stress is the intergranular stress transmitted between solid particles in the soil skeleton, while the pore water pressure is the pressure exerted by the water filling the void spaces between soil particles. According to this principle, the strength and deformation behavior of soils are primarily controlled by the effective stress, rather than the total stress. This concept is crucial in various geotechnical applications, including slope stability analysis, foundation design, and earth pressure calculations. Understanding the effective stress principle is essential for accurately predicting the behavior of soil under different loading conditions and ensuring the stability and safety of engineering structures."中文翻译:“有效应力原理，又称有效张力原理或泰尔扎基原理，是岩土工程和土力学中的基本概念。
积极和消极 英语作文
In the realm of human emotions and experiences,the concepts of positivity and negativity are integral.These two opposing forces shape our perspectives,influence our decisions,and ultimately determine the quality of our lives.Lets delve into the essence of these two contrasting aspects.Positive Aspects of Life:1.Optimism:A positive outlook encourages individuals to see opportunities in every situation.It is the belief that good will prevail,which can lead to increased motivation and resilience in the face of challenges.2.Health Benefits:Studies have shown that positive emotions are linked to better physical health.People who maintain a positive attitude are often found to have stronger immune systems and lower stress levels.3.Productivity:A positive mindset can enhance productivity by fostering creativity and problemsolving skills.It allows individuals to approach tasks with enthusiasm and a sense of purpose.4.Relationships:Positivity attracts people and strengthens social bonds.It is easier to maintain healthy relationships when one is able to communicate effectively and approach conflicts with understanding and empathy.5.Growth Mindset:Embracing positivity often means adopting a growth mindset,where failures are seen as learning opportunities rather than setbacks.This perspective encourages continuous learning and selfimprovement.Negative Aspects of Life:1.Pessimism:A negative outlook can lead to a pessimistic view of life,where one is more likely to expect the worst in every situation.This can result in missed opportunities and a lack of motivation.2.Stress and Anxiety:Constant negativity can increase stress levels,leading to anxiety and other mental health issues.It can create a cycle of worry and fear that is detrimental to overall wellbeing.3.Health Issues:Negative emotions have been linked to various health problems, including heart disease,high blood pressure,and a weakened immune system.4.Isolation:Negativity can push people away,leading to feelings of isolation and loneliness.This can further exacerbate negative emotions and create a vicious cycle.5.Stagnation:A negative mindset can hinder personal growth and development.It can lead to a reluctance to take risks or try new things,which can result in a lack of progress in ones personal and professional life.Balancing Positivity and Negativity:While its important to recognize and understand the negative aspects of life,its equally crucial to strive for a balanced approach.Embracing positivity does not mean ignoring the negative but rather learning to manage and overcome it.Here are some strategies to achieve this balance:1.Mindfulness:Practice being present in the moment,which can help in recognizing and addressing negative thoughts before they spiral out of control.2.Gratitude:Cultivate an attitude of gratitude by regularly reflecting on the things you are thankful for.This can shift your focus from whats wrong to whats right in your life.3.Positive Affirmations:Use positive selftalk and affirmations to reinforce a positive selfimage and counteract negative thoughts.4.Social Support:Surround yourself with positive influences and seek support from friends,family,or professionals when dealing with negativity.5.Healthy Habits:Engage in regular physical activity,maintain a balanced diet,and ensure adequate sleep to support both your physical and mental health.In conclusion,while negativity can provide a realistic perspective on lifes challenges,it is the positivity that often fuels our drive to overcome them.Striving for a balanced approach to lifes ups and downs can lead to a more fulfilling and resilient existence.。
培养条件对雪茄烟优势菌株ZLX10_生长的影响
收稿日期：2022-11-12基金项目：湖北中烟工业有限责任公司科技项目（2021JCYL3SX2B011）广东农业科学2023，50（2）：11-19Guangdong Agricultural SciencesDOI:10.16768/j.issn.1004-874X.2023.02.002潘勇，张贝贝，周亚彬，胡捷，景玉辉，李林林，黄友谊，王剑. 培养条件对雪茄烟优势菌株ZLX10生长的影响［J］. 广东农业科学，2023，50（2）：11-19.培养条件对雪茄烟优势菌株ZLX10生长的影响潘 勇1，张贝贝2，周亚彬2，胡 捷1，景玉辉1，李林林1，黄友谊3，王 剑1（1.湖北中烟工业有限责任公司，湖北 武汉 430040；2.华中农业大学生命科学技术学院，湖北 武汉 430077；3.华中农业大学园艺林学学院，湖北 武汉 430077）摘 要：【目的】微生物在雪茄烟叶发酵过程中起关键作用，为更好地提高雪茄烟品质，需要筛选雪茄优势菌并应用于雪茄烟叶发酵，为此需优化扩大优势菌株的生物量。
【方法】对从雪茄烟中筛选出的一株优势菌株ZLX10进行16S 测序、生理生化分析以及菌株鉴定，同时通过单因素和正交试验优化培养基成分（碳源、氮源和无机盐）及培养条件（接种量、装液量和种龄），以提高其生物量。
【结果】经16S rDNA 序列比对，菌株ZLX10与莫海威芽孢杆菌（Bacillus mojavensis ，MT043920.1）的序列同源性达到99.86%，该菌株具有很强的多糖和蛋白大分子降解能力，可以鉴定为莫海威芽孢杆菌。
经单因素和正交试验得到菌株ZLX10的最优培养基配方为碳源（蔗糖）50 g/L、氮源（酵母提取物）20 g/L、无机盐（MgSO 4） 0.25 g/L，最佳培养条件为接种量1%（V/V）、装液量为250 mL 中装30 mL、种龄24 h。
在最优培养条件下培养24 h，菌株ZLX10的生物量是优化前的1.98倍。
超声振动原位Al2O3（p）
第14卷第4期2023年8月有色金属科学与工程Nonferrous Metals Science and EngineeringVol.14，No.4Aug. 2023超声振动原位Al 2O 3（p ）/7075汽车零件合金组织与耐腐蚀性能研究朱炳耀1， 贾小波*2（1.柳州城市职业学院机电与汽车工程学院，广西 柳州 545006； 2.广西科技大学微电子与材料工程学院，广西 柳州 545006）摘要：通过超声振动在7075合金中添加SiO 2，原位生成Al 2O 3颗粒，利用X 射线衍射仪（XRD ）、自带能谱分析仪（EDS ）的扫描电子显微镜（SEM ）、透射电镜（TEM ）、浸泡腐蚀实验和电化学测试实验对合金的微观组织、物相组成和耐腐蚀性能进行分析。
结果显示，超声振动和Al 2O 3颗粒的原位生成可以细化合金的微观组织，将团聚的Al 2O 3颗粒分散均匀，且Al 2O 3颗粒可作为异质形核的核心，提高形核率。
超声态Al 2O 3（p ）/7075合金主要由Al 、Al 2O 3、Al 7Cu 2Fe 、Al 2CuMg 、Mg 2Zn 相组成。
相比于7075合金，超声态Al 2O 3（p ）/7075合金的失重腐蚀速率和析氢腐蚀速率下降，白色腐蚀产物减少，点蚀和晶间腐蚀程度减弱，自腐蚀电位（E corr ）和点蚀电位（E p ）上升，腐蚀电流密度（I corr ）下降。
超声态Al 2O 3（p ）/7075合金耐腐蚀性能提升是微观组织细化导致的腐蚀速率减缓和Al 2O 3颗粒原位生成导致的腐蚀电位升高的协调作用。
关键词：超声振动；7075合金；Al 2O 3颗粒；微观组织；耐腐蚀性能中图分类号：TG146.2 文献标志码：AStudy on microstructure and corrosion resistance of an in situ Al 2O 3（p ）/7075 alloyfor automotive parts prepared by ultrasonic vibrationZHU Bingyao 1, JIA Xiaobo *2（1. Department of Mechanical and Automotive Engineering ， Liuzhou City Vocational College ， Liuzhou 545006， Guangxi ， China ； 2. School of Microelectronics and Materials Engineering ， Guangxi University of Science and Technology ， Liuzhou 545006， Guangxi ， China ）Abstract: SiO 2 was added into 7075 alloys by ultrasonic vibration to form Al 2O 3 particles in situ. The microstructure ， phase composition and corrosion resistance of the alloy were studied and analyzed by XRD ， SEM ， TEM ， immersion corrosion tests and electrochemical tests ， respectively. The results showed that ultrasonic vibration and in situ formation of Al 2O 3 particles could refine the microstructure of the alloy and disperse the agglomerated Al 2O 3 particles evenly ， and Al 2O 3 particles could be used as the core of heterogeneous nucleation to improve the nucleation rate. The Al 2O 3（p ）/7075 alloys with ultrasonic vibration are mainly composed of Al ， Al 2O 3， Al 7Cu 2Fe ， Al 2CuMg and Mg 2Zn phases. Compared with the 7075 alloys ， its weight loss corrosion rate and hydrogen evolution corrosion rate decreased ， the white corrosion products reduced ， and the degree of pitting and intergranular corrosion weakened. The self-corrosion potential （E corr ） and pitting potential （E p ）increased ， and the corrosion current density （I corr ） decreased. The improvement in the corrosion resistance of the Al 2O 3（p ）/7075 alloy收稿日期：2022-05-07；修回日期：2022-08-25基金项目：2020年度广西高校中青年教师科研基础能力提升项目（2020KY47011）通信作者：朱炳耀（1987— ），讲师，主要研究方向为汽车制造与试验技术，新能源汽车技术。
Stress Management压力处理英文版
Stress ManagementHOW TO REDUCE, PREVENT, AND COPE WITH STRESSIt may seem that there’s nothing you can do about stress. The bills won’t stop coming, there will never be more hours in the day, and your career and family responsibilities will always be demanding. But you have more control than you might think. In fact, the simple realization that you’re in control of your life is the foundation of stress management. Managing stress is all about taking charge: of your thoughts, emotions, schedule, and the way you deal with problemsIN THIS ARTICLE:▪Identify sources of stress▪Look at how you cope with stress▪Avoid unnecessary stress▪Alter the situation▪Adapt to the stressor▪Accept the things you can’t change▪Make time for fun and relaxation▪Adopt a healthy lifestyleIdentify the sources of stress in your lifeLearn about hidden sources of stressWatch 3-min. video: Roadblocks to awarenessStress management starts with identifying the sources of stress in your life. This isn’t as easy as it sounds. Your true sources of stress aren’t always obvious, and it’s all too easy to overlook your own stress-inducing thoughts, feelings, and behaviors. Sure, you may know that you’re constantly worried about work deadlines. But maybe it’s your procrastination,rather than the actual job demands, that leads to deadline stress.To identify your true sources of stress, look closely at your habits, attitude, and excuses:▪Do you explain away stress as temporary (―I just have a million things going on right now‖) even though you can’t remember the last time you took a breather?▪Do you define stress as an integral part of your work or home life (―Things are always crazy around here‖) or as a part of your personality (―I have a lot of nervous energy, that’s all‖).▪Do you blame your stress on other people or outside events, or view it as entirely normal and unexceptional?Until you accept responsibility for the role you play in creating or maintaining it, your stress level will remain outside your control.Start a stress journalA stress journal can help you identify the regular stressors in your life and the way you deal with them. Each time you feel stressed, keep track of it in your journal. As you keep a daily log, you will begin to see patterns and common themes. Write down:▪What caused your stress (make a guess if you’re unsure).▪How you felt, both physically and emotionally.▪How you acted in response.▪What you did to make yourself feel better.Look at how you currently cope with stressThink about the ways you currently manage and cope with stress in your life. Your stress journal can help you identify them. Are your coping strategies healthy or unhealthy, helpful or unproductive? Unfortunately, many people cope with stress in ways that compound the problem.Unhealthy ways of coping with stressThese coping strategies may temporarily reduce stress, but they cause more damage in the long run:▪Smoking▪Drinking too much▪Overeating or undereating▪Zoning out for hours in front of the TV or computer▪Withdrawing from friends, family, and activities ▪Using pills or drugs to relax▪Sleeping too much▪Procrastinating▪Filling up every minute of the day to avoid facing problems▪T aking out your stress on others (lashing out, angry outbursts, physical violence)Learning healthier ways to manage stressIf your methods of coping with stress aren’t contributing to your greater emotional and physical health, it’s time to find healthier ones. There are many healthy ways to manage and cope with stress, but they all require change. You can either change the situation or change your reaction. When deciding which option to choose, it’s helpful to think of the four As: avoid, alter, adapt, or accept.Since everyone has a unique response to stress, there is no ―one size fits all‖ solution to managing it. No single method works for everyone or in every situation, so experiment with different techniques and strategies. Focus on what makes you feel calm and in control.Dealing with Stressful Situations: The Four A’sChange the situation:▪Avoid the stressor.▪Alter the stressor. Change your reaction:▪Adapt to the stressor.▪Accept the stressor.Stress management strategy #1: Avoid unnecessary stress Not all stress can be avoided, and it’s not healthy to avoid a situation that needs to be addressed. You may be surprised, however, by the number of stressors in your life that you can eliminate.▪Learn how to say “no”–Know your limits and stick to them. Whether in your personal or professional life, refuse to accept added responsibilities when you’re close to reaching them. T aking on more than you can handle is a surefire recipe for stress.▪Avoid people who stress you out– If someone consistently causes stress in your life and you can’t turn the relationship around, limit the amount of time you spend with that person or end the relationship entirely.▪Take control of your environment– If the evening news makes you anxious, turn the TV off. If traffic’s got you tense, take a longer but less-traveled route. If going to the market is an unpleasant chore, do your grocery shopping online.▪Avoid hot-button topics– If you get upset over religion or politics, cross them off your conversation list. If you repeatedly argue about the same subject with the same people, stop bringing it up or excuse yourself when it’s the topic of discussion.▪Pare down your to-do list– Analyze your schedule, responsibilities, and daily tasks.If you’ve got too much on your plate, distinguish between the ―shoulds‖ and the ―musts.‖Drop tasks that aren’t truly necessary to the bottom of the list or eliminate them entirely.Stress management strategy #2: Alter the situationIf you can’t avoid a stressful situation, try to alter it. Figure out what you can do to change things so the problem doesn’t present itself in the future. Often, this involves changing the way you communicate and operate in your daily life.▪Express your feelings instead of bottling them up. If something or someone is bothering you, communicate your concerns in an open and respectful way. If you don’tvoice your feelings, resentment will build and the situation will likely remain the same.▪Be willing to compromise. When you ask someone to change their behavior, be willing to do the same. If you both are willing to bend at least a little, you’ll have a good chance of finding a happy middle ground.▪Be more assertive. Don’t take a backseat in your own life. Deal with problems head on, doing your best to anticipate and prevent them. If you’ve got an exam to study for and your chatty roommate just got home, say up front that you only have five minutes to talk.▪Manage your time better.Poor time management can cause a lot of stress. When you’re stretched too thin and running behind, it’s hard to stay calm and focused. But if you plan ahead and make sure you don’t overextend yourself, you can alter the amount of stress you’re under.Stress management strategy #3: Adapt to the stressorIf you can’t change the stressor, change yourself. You can adapt to stressful situations and regain your sense of control by changing your expectations and attitude.▪Reframe problems. Try to view stressful situations from a more positiveperspective. Rather than fuming about a traffic jam, look at it as an opportunity to pause and regroup, listen to your favorite radio station, or enjoy some alone time.▪Look at the big picture. T ake perspective of the stressful situation. Ask yourself how important it will be in the long run. Will it matter in a month? A year? Is it really worth getting upset over? If the answer is no, focus your time and energy elsewhere.▪Adjust your standards. Perfectionism is a major source of avoidable stress. Stop setting yourself up for failure by demanding perfection. Set reasonable standards for yourself and others, and learn to be okay with ―good enough.‖▪Focus on the positive. When stress is getting you down, take a moment to reflect on all the things you appreciate in your life, including your own positive qualities and gifts. This simple strategy can help you keep things in perspective.Adjusting Your AttitudeHow you think can have a profound effect on your emotional and physical well-being. Each time you think a negative thought about yourself, your body reacts as if it were in the throes of a tension-filled situation. If you see good things about yourself, you are more likely to feel good; the reverse is also true. Eliminate words such as "always," "never," "should," and "must." These are telltale marks of self-defeating thoughts.Stress management strategy #4: Accept the things you can’t changeSome sources of stress are unavoidable. You can’t prevent or change stressors such as the death of a loved one, a serious illness, or a national recession. In such cases, the best way to cope with stress is to accept things as they are. Acceptance may be difficult, but in the long run, it’s easier than railing against a situation you can’t change.▪Don’t try to control the uncontrollable. Many things in life are beyond ourcontrol— particularly the behavior of other people. Rather than stressing out over them, focus on the things you can control such as the way you choose to react to problems.▪Look for the upside. As the saying goes, ―What doesn’t kill us makes us stronger.‖When facing major challenges, try to look at them as opportunities for personal growth.If your own poor choices contributed to a stressful situation, reflect on them and learn from your mistakes.▪Share your feelings. T alk to a trusted friend or make an appointment with atherapist. Expressing what you’re going through can be very cathartic, even if there’s nothing you can do to alter the stressful situation.▪Learn to forgive. Accept the fact that we live in an imperfect world and that people make mistakes. Let go of anger and resentments. Free yourself from negative energy by forgiving and moving on.Stress management strategy #5: Make time for fun and relaxationBeyond a take-charge approach and a positive attitude, you can reduce stress in your life by nurturing yourself. If you regularly make time for fun and relaxation, you’ll be in a better place to handle life’s stressors when they inevitably come.Healthy ways to relax and recharge▪Go for a walk.▪Spend time in nature.▪Call a good friend.▪Sweat out tension with a good workout.▪Write in your journal.▪T ake a long bath.▪Light scented candles. ▪Savor a warm cup of coffee or tea. ▪Play with a pet.▪Work in your garden.▪Get a massage.▪Curl up with a good book.▪Listen to music.▪Watch a comedy.Don’t get so caught up in the hustle and bustle of life that you forget to take care of your own needs. Nurturing yourself is a necessity, not a luxury.▪Set aside relaxation time.Include rest and relaxation in your daily schedule. Don’t allow other obligations to encroach. This is your time to take a break from allresponsibilities and recharge your batteries.▪Connect with others.Spend time with positive people who enhance your life. A strong support system will buffer you from the negative effects of stress.▪Do something you enjoy every day.Make time for leisure activities that bring you joy, whether it be stargazing, playing the piano, or working on your bike.▪Keep your sense of humor.This includes the ability to laugh at yourself. The act of laughing helps your body fight stress in a number of ways.Stress management strategy #6: Adopt a healthy lifestyleYou can increase your resistance to stress by strengthening your physical health.▪Exercise regularly. Physical activity plays a key role in reducing and preventing the effects of stress. Make time for at least 30 minutes of exercise, three times per week.Nothing beats aerobic exercise for releasing pent-up stress and tension.▪Eat a healthy diet. Well-nourished bodies are better prepared to cope with stress, so be mindful of what you eat. Start your day right with breakfast, and keep your energy up and your mind clear with balanced, nutritious meals throughout the day.▪Reduce caffeine and sugar. The temporary "highs" caffeine and sugar provide often end in with a crash in mood and energy. By reducing the amount of coffee, soft drinks, chocolate, and sugar snacks in your diet, you’ll feel more relaxed and you’ll sleep better.▪Avoid alcohol, cigarettes, and drugs. Self-medicating with alcohol or drugs may provide an easy escape from stress, but the relief is only temporary. Don’t avoid or mask the issue at hand; deal with problems head on and with a clear mind.▪Get enough sleep. Adequate sleep fuels your mind, as well as your body. Feeling tired will increase your stress because it may cause you to think irrationally.▪Stress Management & Relief▪Helpguide’s Free Toolkit▪Resources & ReferencesStress Management & ReliefRelaxation Techniques By practicing techniques that activate your body’s relaxation response you can effectively combat stress and ease tension.Quick Stress Relief Identify your own stress responses and learn how to quickly and effectively reduce stress in the middle of any challenging situation.How to Stop Worrying You can break the habit of chronic worrying by training your brain to stay calm and overcome persistent doubts and fears.The Many Faces of Stress by Harvard Health Publications Learn more about stress challenges that you can learn to cope with.Helpguide’s Free ToolkitIf you feel too overwhelmed to put these tips into practice, repair what may be the source of the problem–an inability to stop worrying or manage overwhelming stress and emotions. T ake advantage of Helpguide's free Bring Your Life Into Balance mindfulness toolkit. This resource can help you learn to manage deeper, older and more complex sources of stress.Resources & ReferencesGeneral information about managing and coping with stressManaging Stress: A Guide for College Students – Offers a total wellness lifestyle plan for managing, reducing, and coping with stress. (University Health Center, University of Georgia)Stress Management: How Do You React During Stressful Situations? – Evaluate the way you react to stress and learn how to transform your negative responses. (Mayo Clinic)Stress Management for Parents – Stress management suggestions for stressed-out parents, including fifty-two proven stress reducers. (Child Development Institute)Stress management strategiesAssert Yourself – Self-help modules designed to help you reduce stress, depression, and anxiety by improving your assertiveness. (Centre for Clinical Interventions)Put Off Procrastinating – Work your way through a self-help series on how to stop procrastination problems. (Centre for Clinical Interventions)What Are Some Specific Stress Reduction Methods? – Simple stress reduction suggestions, including diet, exercise, and cognitive-behavioral techniques. (University of Maryland Medical Center)Exercise Fuels the Brain's Stress Buffers – Explains how regular exercise helps reduce and manage stress levels. (American Psychological Association)Authors: Melinda Smith, M.A. and Robert Segal, M.A. Last updated:July 2012.。
高考英语考试卷题
Part I Listening Comprehension (25 points)Section A (5 points)In this section, you will hear five short conversations. At the end of each conversation, a question will be asked about what was said. Both the conversation and the question will be spoken only once. After each question, there will be a pause. During the pause, you must read the four choices marked A), B), C) and D), and decide which is the best answer. Then mark the corresponding letter on Answer Sheet 1 with a single line through the center.1. A) The man is going to the library.B) The woman is studying for an exam.C) The woman is helping the man with his homework.D) The man is not sure what to do.2. A) They are discussing a movie.B) They are planning a trip.C) They are comparing their diets.D) They are discussing their daily routines.3. A) The man is feeling sick.B) The woman is feeling sick.C) The man is taking medicine.D) The woman is taking medicine.4. A) They are going to a concert.B) They are going to a movie.C) They are going to a restaurant.D) They are going to a bookstore.5. A) The man is suggesting a change of plan.B) The woman is suggesting a change of plan.C) They are discussing a problem.D) They are resolving a conflict.Section B (20 points)In this section, you will hear a passage three times. When the passageis read for the first time, you should listen carefully for general ideas. When the passage is read for the second time, you are required to fill in the blanks with the exact words you have just heard. For blanks numbered 6 to 13, you can fill in the missing words you have just heard in the corresponding spaces on Answer Sheet 1. For blanks numbered 14 to 20, you are required to write your answers in no more than 3 words. You can mark the corresponding letter on Answer Sheet 1 with a single line through the center if you choose to.6. ___________ is the main topic of this passage.7. The author mentions that ___________ can be divided into two types.8. The first type of invention is ___________.9. The second type of invention is ___________.10. ___________ is an example of the first type of invention.11. ___________ is an example of the second type of invention.12. The author suggests that ___________.13. The passage concludes with the idea that ___________.14. ___________ is the process of creating something new.15. ___________ is a new product or device.16. ___________ is the process of improving existing products.17. ___________ is a type of invention that is a significant improvement.18. ___________ is a device that has not been invented yet.19. ___________ is a device that has been improved upon.20. ___________ is a device that is currently available.Part II Reading Comprehension (40 points)Section A (20 points)Read the following passage and answer the questions below it.The internet has revolutionized the way we communicate, access information, and conduct business. However, it has also brought about a new set of challenges, particularly in the realm of privacy and security. One of the most pressing issues is the use of personal data by corporations and governments.Corporations collect vast amounts of data on consumers through various online platforms. This data is used to tailor advertising, improve services, and analyze consumer behavior. While this can lead to more personalized experiences, it also raises concerns about privacy. Consumers often have little control over how their data is used and shared, and they may not be fully aware of the extent of data collection.Governments also collect and use personal data, but for different purposes. They argue that this is necessary for national security and public safety. However, there have been instances where personal datahas been misused or mishandled, leading to breaches of privacy and even discrimination.To address these concerns, several measures have been proposed. One is the implementation of stricter data protection laws. These laws would require companies to obtain explicit consent before collecting personal data and to ensure that data is securely stored and only used for the purposes for which it was collected.Another measure is the promotion of transparency. Companies should be transparent about their data collection practices and provide consumers with the ability to access and control their personal data.Lastly, there is a need for public awareness and education. Consumers should be informed about their rights and how to protect their privacy online.Section B (20 points)Read the following passage and answer the questions below it.The importance of exercise cannot be overstated. It is well-known that regular physical activity can improve cardiovascular health, strengthen muscles, and enhance mental well-being. However, exercise also has numerous other benefits that are often overlooked.One of the lesser-known benefits of exercise is its impact on cognitive function. Studies have shown that regular exercise can improve memory, attention, and problem-solving skills. This is particularly importantfor students who are trying to excel academically.Exercise also plays a crucial role in stress management. Physicalactivity can reduce levels of stress hormones such as cortisol, which can have a negative impact on mental health. Additionally, exercise can provide a sense of accomplishment and improve self-esteem.Another important benefit of exercise is its impact on social relationships. Participating in group sports or fitness classes can help build social connections and foster a sense of community. This is particularly beneficial for individuals who may feel isolated or lonely.Despite the numerous benefits of exercise, many people still struggle to incorporate it into their daily routines. This can be due to a variety of factors, including lack of time, lack of motivation, or lack of access to facilities. To overcome these barriers, it is important tofind activities that are enjoyable and sustainable.In conclusion, exercise is not just beneficial for physical health; it also has a profound impact on mental and social well-being. It is essential that individuals make exercise a priority in their lives to reap these numerous benefits.Questions:21. What is the main idea of the passage?A) The benefits of exercise on physical health.B) The benefits of exercise on mental health.C) The benefits of exercise on social relationships.D) The importance of incorporating exercise into daily routines.22. According to the passage, which of the following is a lesser-known benefit of exercise?A) Improving cardiovascular health.B) Enhancing mental well-being.C) Improving cognitive function.D) Reducing stress levels.23. What is one of the factors that can prevent individuals from incorporating exercise into their daily routines?A) Lack of time.B) Lack of motivation.C) Lack of access to facilities.D) All of the above.24. How does exercise impact social relationships?A) It can help build social connections.B) It can foster a sense of community.C) It can improve self-esteem.D) All of the above.25. What is the author's overall conclusion about exercise?A) Exercise is only beneficial for physical health.B) Exercise is beneficial for mental and social well-being.C) Exercise is not important for students.D) Exercise should be avoided at all costs.Part III Writing (25 points)26. Write an essay of about 150 words on the following topic:The Importance of ReadingIn your essay, you should:1. State the importance of reading in one's life.2. Provide examples to support your point.3. Conclude with your personal opinion on the topic.You should write neatly on Answer Sheet 2. Do not write your name. Do not use any abbreviations or words other than those given in the question.End of the Test。
双位错滑移运动的晶体相场模拟
双位错滑移运动的晶体相场模拟杨瑞琳;刘瑶;胡绪志;卢强华;高英俊【摘要】Objective]The effects of crystal dislocation movement on mechanical behaviors of materials processing are studied.[Methods]The feature of the gliding of double dislocation un-der shear strain are simulated by the improved phase-field-crystal(PFC).[Results]The simula-tion results show that the double dislocation of the system only glides without climbing under stress,and keeps moving at a constant speed,while their directions are parallel,but opposite. When the strain rate is small,it requires a certain incubation time to overcome the barrier, therefore,the slipping of dislocation looks like a bumpy way.When the strain rate is larger,the dislocation glides uniformly in a straight line,while the strain rate is relatively smaller,the gli-ding is of the bumpy motion.[Conclusion]PFC model can be well used to study the dislocation movement under the effect of strain.%【目的】研究晶体位错运动对材料加工力学性能的影响。
六氟丙烯装置再沸器腐蚀原因分析与处理_张国亮
··················氟化工收稿日期：2013-07-16六氟丙烯装置再沸器腐蚀原因分析与处理张国亮（巨化股份有限公司氟聚合物事业部，浙江衢州324004）摘要对六氟丙烯（HFP ）生产装置精馏系统塔底再沸器下封头环焊缝发生沟状腐蚀的原因进行分析，主要原因是在装置特定介质环境中，发生应力状态下的晶间腐蚀。
通过对工艺流程优化，设备材质及焊接工艺的改进，取得了较好的效果，达到了防腐蚀目的。
关键词六氟丙烯；再沸器；焊缝；应力；腐蚀中图分类号TQ050.9+6文献标识码B DOI 10.3969/j.issn.1006-6829.2013.05.005国内某氟化工企业六氟丙烯（HFP ）生产装置，后系统采用多塔精馏分离提纯取得HFP 产品，精馏系统3#塔底再沸器在运行过程中发现下封头环焊缝靠封头侧约60mm 段内有3处发生穿孔泄漏。
采用应急措施对3#塔与系统隔离，对再沸器拆检，发现封头整圈环焊缝熔合线区沟状腐蚀，靠封头侧尤其严重，部分区域表面上腐蚀宽度达7mm 左右，并向接头内部逐渐变窄。
封头内壁呈光亮状；高颈法兰内壁呈黑色，疏松状。
封头壁厚测量7.6mm 左右无明显减薄现象。
针对设备缺陷情况和实际微酸性工作介质环境分析腐蚀的主要原因，通过对工艺流程优化，设备材质及焊接工艺的改进，以达到防腐蚀目的。
1缺陷及返修情况该再沸器技术参数：工作压力，壳0.3MPa ，管0.8MPa ；工作温度，壳143℃，管143℃；工作介质，壳蒸汽，管八氟环丁烷（C-318）、HFP ；介质特性：中度危害。
下封头及高颈法兰材料均为0Cr18Ni9，封头壁厚8mm 。
0Cr18Ni9材料间焊接采用A132焊条。
根据该腐蚀情况，实施返修工作。