高耐磨合金钢电弧喷涂药芯焊丝及应用研究

华中科技大学

硕士学位论文

高耐磨合金钢电弧喷涂药芯焊丝及应用研究

姓名：戴明辉

申请学位级别：硕士

专业：材料工程

指导教师：余圣甫

2011-05-25

华 中 科 技 大 学 硕 士 学 位 论 文

摘要

本论文研究成分配比不同的几种合金钢电弧喷涂药芯焊丝，在低碳钢表面进行喷涂形成高耐磨的高合金钢电弧喷涂涂层。测试电弧喷涂涂层的显微硬度、耐磨粒磨损性能、孔隙率以及与基体的结合强度；通过金相显微镜、环境扫描电子显微镜（ESEM）、EDS能谱仪等分析手段研究了电弧喷涂涂层的微观结构；分析了Al、Ni、B对涂层性能以及组织结构的影响。

研究结果表明：喷涂药芯焊丝中Al含量的增加，并不能提高其结合强度。Al 在电弧喷涂雾化阶段烧损较大，形成氧化铝，沉积在涂层表面时不利于金属雾化颗粒融合，成为夹渣，形成孔隙，降低涂层与基体的结合强度。因此Al含量增加，涂层的孔隙率增加，显微硬度与耐磨性下降。

涂层中的B与Fe形成FeB与Fe2B的混合相，能与基体有效结合，与Ni形成Ni-Cr-B-Si系自熔合金，有良好的浸润性，因此B能促进涂层与基体的结合强度。此外，B还与C形成B4C硬质相，还能与Cr形成硼铬化物CrB，Cr2B硬质相，分布在涂层中，提高涂层的耐磨性。Ni在涂层中的主要作用是形成Ni-Cr-B-Si系自熔合金，提高涂层与基体的结合强度，对涂层的孔隙率、硬度以及耐磨性作用不明显。

通过对涂层表面的磨损形貌分析，表明涂层表面的磨损机理为微观切削磨损机理，磨粒在涂层表面主要产生压痕而不是切屑。涂层中的孔隙与夹渣易于形成切屑，降低了涂层的耐磨性。

用研制的药芯焊丝对搅拌车的落料槽进行电弧喷涂，有效地提高了使用寿命，取得了良好的效果。

关键词：电弧喷涂；药芯焊丝；合金元素；耐磨性；结合强度

华 中 科 技 大 学 硕 士 学 位 论 文

Abstract

In the paper, we designed and investigated several alloy steel composition of flux cored wires for arc spraying. Alloy steel coatings with high wear resistance were deposited on low carbon steel surface. Micro-hardness, abrasive wear resistance, porosity, and the bonding strength of the arc sprayed coating were tested. Through the microscope, environmental scanning electron microscope (ESEM), EDS analysis, the microstructure of arc sprayed coatings was studied, moreover, the effects of Al, Ni, B on the coating performance and structure were also analyzed and assessed.

The results manifested that with the increase of Al content, the bonding strength was not improved. In the arc spray atomization stage, Al was burned and transformed into aluminum oxide to deposit on the surface of the coatings. As aluminum oxide could not easily integrate with the metal aerosol particles and became slag, then a large number of pores formed, as a result, the bonding strength of the coating and substrate would reduce. And the loss was more than that for the exothermic reaction. Therefore, as the Al contents increased, the porosity of coating increased, and the hardness and wear resistance decreased.

Since B combined with Fe to form the mixed phases FeB and Fe2B, which could effectively bind with substrate, and B and Ni could form the Ni-Cr-B-Si self-fluxing alloy system with good infiltration, so B could promote the bonding strength of coating and substrate. In an addition, B with C or Cr could form B4C or CrB，Cr2B, these hard phases was able to enhance wear resistance of the coating. While Ni was mainly used to form the Ni-Cr-B-Si self-fluxing alloy system, it could promote the bonding strength of coating, but its role to the porosity, hardness and wear resistance of coating was not obvious.

According to the analysis of the wear of the coating surface, it was determined that the wear mechanism was micro-cutting wear, for the abrasives produced indentation but not chips on the coating surface. And the porosity and slag were conducive to the formation of chip, which finally reduced the wear resistance of the coating.

The cored wire with the best performance in this paper was utilized for arc spraying