波长色散X荧光光谱法测定润滑油中15种元素

波长色散X 荧光光谱法测定润滑油中15种元素
汪鹤鸣
(紫金矿业集团股份有限公司,福建上杭　364200)
[摘　要]　本试验选择了3.6μm 迈拉膜制成的样杯,使用PW 4400型X 荧光光谱仪自带oil⁃trace 分析软件,建立了润滑油样品中铁㊁铜㊁锡㊁铝㊁硅㊁钼㊁锰㊁锌㊁磷㊁钙㊁镍㊁铬㊁钠㊁镁㊁铅等15种元素同时测定的分析方法㊂各元素检测结果准确度高㊁精密度好,各元素的检出限在0.32~4.93μg /mL ㊂作为润滑油中添加剂和磨损金属的检测方法,该方法操作简便㊁快速㊁准确㊂[关键词]　波长色散;X 荧光光谱;润滑油;添加剂;磨损
[中图分类号]　TF03+.1 [文献标志码]　B [文章编号]　1672⁃⁃6103(2018)05⁃⁃0061⁃⁃05
[作者简介]汪鹤鸣(1983 ),男,江西婺源人,工程师,从事矿山及冶炼行业分析化学方面的工作㊂[收稿日期]2017⁃⁃10⁃⁃10
为减少机械设备中相对运动表面间的摩擦与磨
损,通常在运动表面添加润滑油起到润滑作用㊂由于设备在运行过程中磨损的金属微粒进入润滑系统,金属微粒携带着机器运转状态的大量信息,因此,对润滑油中金属微粒成分的监测和研究可以为设备故障预警和诊断提供依据[1]㊂
目前,润滑油中添加剂和磨损造成的污染元素
常用的检测方法主要集中在原子吸收光谱法㊁电感耦合等离子体发射光谱法㊁紫外可见分光光度法等,这些方法大多需灰化消解等前处理过程,用到大量的酸和灰化助剂,从而易引入杂质元素,且易挥发元素容易损失,检测周期较长[2-4]㊂本文通过使用X 荧光光谱仪,建立了测定润滑油中铁㊁铜㊁锡㊁铝㊁硅㊁钼㊁锰㊁锌㊁磷㊁钙㊁镍㊁铬㊁钠㊁镁㊁铅等15种元素的分析方法,该方法检测样品不需要前处理,是一种快速㊁高效㊁准确度高的方法㊂
1　试验部分
1.1　仪器及材料
PANalytical PW 4400型X 射线荧光光谱仪,oil⁃
trace 分析软件,氦气光路介质,3.6μm 及6μm 迈拉膜(Mylar),多元素国际油标及基体校正油样,液体样品杯㊂
1.2　迈拉膜(Mylar )的选择
通过多次试验发现,制作液体样品杯时用的迈拉膜(Mylar)厚度对样品分析结果影响明显㊂具体数据见图1㊂
根据X 荧光光谱仪工作的机理,X 射线对轻元素激发效率相对较差,分析的条件也较苛刻,由于购进X 荧光光谱仪时配备的6μm 的迈拉膜较厚,降低了钠㊁镁等轻元素分析的灵敏度,因此,本文采用3.6μm 的迈拉膜制作样品杯进行液体样品检测㊂
1.3　样品制备
由于每个元素对液体样品的测量厚度要求不一样,因此所用液体体积尽可能达到无限厚,体积应保持恒定[5]㊂通过试验,确定了样品杯中加入12g 样品能满足分析要求㊂用3.6μm 迈拉膜和直径35mm 进口无底组合塑料杯组装成样杯后,将杯置于电子天平上,清零后称取经激烈摇动后的12g 油样,排去气泡,盖好杯盖,观察底部迈拉膜无皱褶㊁气泡等异样后,立即置液体杯中待测,不宜久置㊂1.4　测量条件的选择
应用oil⁃trace 分析方法模板推荐的测量条件,见图2方法建模条件截图㊂
1.5　标准样品的选择
选用空白标油(0ppm),10ppm,30ppm,50ppm,100ppm,300ppm,500ppm,900ppm,3000ppm
和6个基体校正样㊂1.6　校准曲线绘制
本方法选用9个国际标油和6个基体校正样,
㊃16㊃　2018年10月第5期 汪鹤鸣:波长色散X 荧光光谱法测定润滑油中15种元素===============================================
图1　使用3.6μm 与6μm 迈拉膜的试验数据对比截图
图2　方法建模条件截图
采用oil⁃trace 分析软件设定的基体校正模式,根据共存元素谱线重叠特性进行相关元素谱线重叠校正,获得较好的线性,相关系数r 均达到0.999以上㊂
以金属Al 为例,所建立的元素工作曲线截图见图3㊂
2　结果与讨论
2.1　样杯制作材料与测定结果关系
试验在同等分析测量条件下,采用6μm 迈拉膜制作成的样杯㊁测定样品时降低了方法的灵敏度,尤其对钠,镁,铝,硅,磷等轻元素影响严重,其中钠㊁
㊃
26㊃中国有色冶金 A 生产实践篇·分析检测　===============================================
图3　润滑油中铝元素工作曲线截图　
镁两种元素的准确度,精密度和检出限均达不到技术规范要求㊂用3.6μm迈拉膜制作成的样杯能满足技术规范要求,获得较好的质量参数㊂但样杯不能多次重复测量(重复测量不要超过5次),否则样杯裂漏,油样渗漏滴入真空分析腔内,污染和损坏测量元件
2.2　样杯制作过程控制与样品制作过程控制
液态样杯制作与待测样品制作过程控制是本方法质量控制的关键点㊂由于制作样杯时迈拉膜易粘在手上,容易造成钠元素的污染,称样时和放置样品时迈拉膜贴近的平面也容易污染迈拉膜,所以在制作样品时,手不要接触迈拉膜的平面㊂油样在称取之前要摇匀,称取后排去气泡,观察迈拉膜无皱褶或凸出渗漏立即测试,不宜久置㊂
2.3　方法的精密度和准确度
分别对三个较低的标样10ppm㊁50ppm㊁100 ppm进行12次测量,计算准确度和精密度均符合技术规范要求㊂详见表1~3㊂
2.4　检出限
本文采用校准曲线法计算各元素的检出限㊂计算见下式㊂
LLD=32×-ab
1000T 式中:a 校准曲线斜率;
b 校准曲线截距;
T 谱峰和背景总测量时间;
1000 计数率因数㊂
用此法计算检出限的优点是避免了由于净强度差减不准确而导致单位含量计数率(m)的失真现象㊂经计算,各元素的检出限见表4㊂
3　结论
本试验研究,选择了3.6μm迈拉膜制成的样杯,在氦气光路介质中,使用PW4400型X荧光光谱仪4.0L版本自带oil⁃trace分析软件进行基体校正,绘制校准曲线进行检测,建立了润滑油样品中15种元素同时测定的分析方法,较好的解决了钠镁两种轻元素检测的准确度和精密度问题,各元素的准确度和精密度都在8%之内,并拥有较低的检出限,各元素的检出限在0.32~ 4.93μg/mL之间,作为润滑油中添加剂和磨损金属检测方法,该方法操作简便㊁快速㊁准确㊂有助于定性地指导润滑油分析,进行设备运行磨损状态的监测和预警㊂
㊃36㊃
　2018年10月第5期 汪鹤鸣:波长色散X荧光光谱法测定润滑油中15种元素
===============================================
表1　10μg /mL 标准油的准确度和精密度
序号单位Fe Cu Na Mg Al Si P Ca Cr Mn Ni Zn Mo Sn Pb 1ppm 11
8.710.110.99.6
8.79.3
10.411
10.69.611.310.29.5
10
2ppm 10.18.89.4
10.511.38.910.19.610.110.19
10.79.810.59.33ppm 10.58.7
10.89.8
11.39.9109.710.310.49.310.59.110.29.74ppm 9.210.19.510.910.99.410.99.2
10.410.2109.7
8.99.29.25ppm 9.99.7910.69.99.1
10.210.710.310.39.610.49
9.39.16ppm 109.110.49.310.110.810101010.19.59.99.910.69.47ppm 9.110.2109.19.89.51011.310.611.59.81099.79.18ppm 10.69.910
9.69.69.49.7
10.310.210.49.29.19.710.39.39
ppm 910.29.39.89.49.510.910.210.210.59.810.19.799.310ppm 109.79.69.29.99.99.4
10.51010.69.49.39.69.59.511ppm 9.810.1
9.91099.310.410.210.510
9.710.49.19.7
9.412ppm 109.19.19109.79.610.410.310.39.59.4910.89.7平均值ppm 9.9
9.59.89.9
10.19.51010.210.310.49.510.19.49.99.4最小值ppm 98.79998.79.39.2101099.18.999.1最大值ppm 1110.210.810.911.310.810.911.31111.51011.310.210.810标准偏差S ppm 0.60.60.540.70.720.550.520.550.290.40.290.630.430.60.28精密度RSD %6.06
6.35.52
7.027.145.745.155.362.763.8736.274.586.12.92准确度RE
%
-0.69-4.87-2.42-1.06
0.74-50.42.083.264.2-4.660.71
-5.79-1.4-5.78表2　50μg /mL 标准油的准确度和精密度
序号单位Fe Cu Na Mg Al Si P Ca Cr Mn Ni Zn Mo Sn Pb 1ppm 48.649.854.147.150.851.749.049.149.849.549.051.349.550.147.92ppm 49.250.852.250.751.952.552.751.450.149.848.851.849.450.447.63ppm 49.052.649.251.452.949.550.550.650.850.051.454.749.649.349.54ppm 48.352.747.349.250.848.558.053.853.252.351.054.249.649.749.85ppm 50.149.848.650.250.750.349.749.449.749.849.750.750.251.949.16ppm 49.850.049.450.150.249.850.550.950.150.250.350.849.849.650.07ppm 49.550.449.450.451.950.650.750.850.150.350.350.649.649.049.68ppm 49.950.150.150.950.750.450.150.550.350.250.150.849.549.750.89
ppm 49.550.651.550.450.950.750.750.950.350.950.350.350.050.850.110ppm 49.150.550.450.650.150.250.750.650.250.950.550.149.450.051.211ppm 49.750.149.450.350.950.750.850.650.350.450.550.849.649.651.012ppm 50.749.351.649.249.050.549.549.349.549.949.649.649.650.249.6平均值ppm 49.550.650.350.050.950.451.150.750.450.450.151.349.650.049.7最小值ppm 48.349.347.347.149.048.549.049.149.549.548.849.649.449.047.6最大值ppm 50.752.754.151.452.952.558.053.853.252.351.454.750.251.951.3标准偏差S ppm 0.661.071.831.130.991.012.361.220.950.730.771.580.250.761.11精密度RSD %1.342.123.642.261.952.014.622.421.881.451.543.070.511.522.23准确度RE
%
-1.09
1.11
0.53
0.07
1.79
0.9
2.15
1.32
0.72
0.71
0.24
2.63
-0.73
0.05
-0.64
㊃
46㊃中国有色冶金 A 生产实践篇·分析检测　===============================================
表3　100μg /mL 标准油的准确度和精密度
序号单位Fe Cu Na Mg Al Si P Ca Cr Mn Ni Zn Mo Sn Pb 1ppm 98.2101.498.5
99.0101.599.595.597.998.8100.2100.7103.4100.7102.6101.42ppm 97.0100.5100.699.8
104.198.993.796.997.9100.8100.4103.6101.3101.9101.33ppm 94.4100.898.5100.3106.999.692.597.298.6100.6100.3102.6101.099.8
100.94ppm 96.2101.397.3100.2104.799.9
94.1
97.598.0
100.0100.3102.9101.1100.7101.55ppm 99.6
98.197.295.5102.2100.9101.599.7100.998.7101.1102.199.1101.799.06ppm 101.398.299.699.0103.2102.198.599.9100.898.5101.5101.899.0102.999.07ppm 102.098.0103.8100.8
100.3100.699.998.6100.498.2101.5101.899.3103.198.88ppm 99.498.396.599.2103.199.799.698.7100.398.6100.8101.398.6101.499.09
ppm 102.998.3101.798.7104.0103.799.298.8100.899.0101.3101.398.9104.699.110ppm 100.698.796.997.299.3
100.8100.599.3100.499.1101.2101.999.0102.698.911ppm 101.298.895.399.1102.299.096.698.6
100.498.1101.6101.598.9102.899.212ppm 101.498.598.598.799.899.8101.0100.8100.998.7101.1103.499.5103.099.0平均值ppm 99.599.298.799.0102.6100.497.798.699.899.2101.0102.399.7102.399.8最小值ppm 94.498.095.395.599.398.992.596.997.998.1100.3101.398.699.898.8最大值ppm 102.9101.4103.8100.8106.9103.7101.5100.8100.9100.8101.6103.6101.3104.6101.5标准偏差S ppm 2.581.342.41.432.211.363.111.151.190.950.460.851.021.261.13精密度RSD %2.591.35
2.431.452.151.36
3.181.171.190.96
0.450.831.021.231.13准确度RE
%
-0.48-0.77-1.29-1.052.610.37-2.29-1.35-0.16-0.80
1.00
2.30
-0.29
2.26-0.25
表4　各元素的检出限表
μg /mL
元素Fe Cu Na Mg Al Si P Ca Cr Mn Ni Zn Mo Sn Pb 检出限
1.63
1.10
3.27
3.70
1.50
2.4
4.93
2.95
0.32
0.58
0.51
0.74
1.10
4.43
0.96
[参考文献]
[1]　刘混举,徐世平.基于油液分析状态监测的预知维修方法[J].
矿山机械,1996(6):45-47.
[2]　童式国,胡明芬,雷玉叶.ICP⁃AES 法测定航空润滑油中痕量磨
损金属的研究[J].四川大学学报:自然科学报,1993,30(3):421-424.
[3]　杨建.等离子体发射光谱法测定重油及润滑油中8种金属元
素含量[J].石化技术,1996,3(4):252-258.
[4]　田旻洁,周海明,闵红,林苗.全反射X 射线荧光光谱法直接测
定润滑油中的10种微量金属元素[J].分析实验室,2013,32(12):16-20.
[5]　吉昂,陶光仪,卓尚军,罗立强.X 射线荧光光谱分析[M].北
京:科学出版社,2003:210-211.
Determination 15elements in lubricating oil by wavelength dispersion
X⁃ray fluorescence spectrometry
WANG He⁃ming
Abstract :The sample cup made of 3.6um Myra membrane is used for the test,using PW 4400X⁃ray fluorescence spectrometer with oil⁃trace analysis software.Analysis method for the determination of fifteen elements (iron,cop⁃per,tin,aluminum,silicon and molybdenum,manganese,zinc,phosphorus,calcium,nickel,chromium,sodi⁃um,magnesium etc.)in lubricating oil is established.The test results of each element are highly precise and very
accurate.The detection limit of each element is between 0.32~4.93μg /mL.The method is simple,rapid and ac⁃curate as a detection method of additives and wear metals in lubricating oil.
Key words :wavelength dispersion;X⁃ray fluorescence spectrum;lubricating oil;additive;wear
㊃56㊃　2018年10月第5期 汪鹤鸣:波长色散X 荧光光谱法测定润滑油中15种元素===============================================。