钴基合金等离子熔覆工艺研究与优化

目的优化钴基合金等离子熔覆工艺参数,提高熔覆层的成形质量。方法以熔覆于Q235钢表面的多道钴基合金耐磨涂层为研究对象,开展正交试验,利用MIRA3X-MHX型扫描电子显微镜分析涂层组织结构及不同区域的物相成分,采用KEYENCE VHX-5000超景深显微镜和HXD-1000TMC/LCD维氏显微硬度计对熔覆层表面平整度和横断面的显微硬度进行测量分析,并结合灰关联分析法和极差分析法,探究工作电流、扫描速度和送粉速度对熔覆层表面平整度和显微硬度的综合影响,优化出最佳工艺参数组合。结果工作电流对熔覆层成形质量的影响最为显著,其次是扫描速度、送粉速度。各组熔覆层横断面纵向显微硬度的波动情况大致相同,且最大显微硬度均出现在距离上表层约0.4 mm处,熔覆层平均显微硬度是基体材料的3倍多。熔覆层中上部的组织结构分布均匀且致密,随着熔覆层深度的增加,熔覆层稀释率呈增大趋势,显微硬度逐渐降低。在工作电流为95 A、扫描速度为90 mm/min、送粉速度为12r/min的工艺参数下,熔覆层与基板结合良好,无气孔和空隙,横断面平均显微硬度较高,且熔覆层表面较为平整。结论经等离子熔覆成形质量工艺参数优化后,熔覆层表面性能有效提高,该结果可为等离子熔覆技术应用于易磨损工件的耐磨性研究提供参考。

Plasma Cladding Process for Co-based Alloy and Its Optimization

The work aims to improve the forming quality of the cladding coating by optimizing the process parameters in plasma cladding of cobalt-based alloy. The multitrack Co-based alloy wear-resistant coatings coated on Q235 steel were taken as the research object to carry out the orthogonal experiment. The microstructure and phase composition of coatings in different regions were analyzed by MIRA3X-MHX scanning electron microscope, and the surface smoothness and the microhardness of cross section of the coatings were measured and analyzed by KEYENCE VHX-5000 ultra-depth-of-field microscope and HXD-1000TMC/LCD Vickers microhardness tester. The comprehensive effects of working current, scanning speed and powder feeding speed on the surface smoothness and microhardness of the cladding layer were investigated by grey correlation analysis and range analysis, and then the optimum technological parameters were obtained. The working current had the most significant effect on the forming quality of cladding layer, followed by scanning speed and powder feeding speed. The fluctuation of longitudinal microhardness in cross section of each cladding layer was roughly the same, the maximum microhardness appeared about 0.4 mm away from the upper surface layer, and the average microhardness of the cladding layer was more than 3 times that of the matrix material. The distribution of microstructure in the upper part of the cladding layer was uniform and dense. With the decrease of the distance between the cladding layer and the substrate, the dilution rate of the cladding layer increased and the microhardness decreased gradually. Under the combination of working current of 95 A, scanning speed of 90 mm/min and powder feeding speed of 12 r/min, the cladding layer was well combined with the substrate without gas holes and clearances, the average microhardness of cross section was higher and the surface of the cladding layer was more flat. The surface properties of the cladding layer are effectively improved by optimizing the process parameters of plasma cladding forming quality. The results can provide a reference for the study on the plasma cladding technology applied to the wear resistance of wearable workpieces.