球形WC增强铁基复合等离子堆焊层的组织与摩擦学性能

为提高304不锈钢的摩擦学性能,将质量分数为30%和60%的球形WC添加到铁基复合粉末,采用等离子堆焊技术在其表面制备了WC增强铁基复合涂层.分析其显微组织结构、物相和显微硬度,在恒定载荷(50 N)和滑动速度(20 mm/s)下进行干摩擦磨损试验,研究其干滑动摩擦学性能.结果表明:富含Cr的固溶强化奥氏体、高硬度的Cr7C3和WC增强相的存在,提高了WC增强铁基堆焊层的硬度,30%WC和60%WC涂层的显微硬度达到HV0.2665和HV0.2724,比铁基涂层提高了21.1%和31.9%,是304基体的3.7和4倍;30%WC和60%WC涂层的摩擦系数和磨损率分别为0.59和2.639×10~(–6) mm~3·N~(–1)·m~(–1),0.42和1.111×10~(–6) mm~3·N~(–1)·m~(–1).30%WC和60%WC涂层均表现出优异的耐磨性能,其磨损机理分别为黏着磨损和二体磨粒磨损的混合机制,和三体磨粒磨损.

Microstructure and Tribological Properties of Fe-based Composite Coatings Reinforced by Spherical WC Particles using Plasma Transferred Arc

In order to improve the wear resistance of 304 austenitic stainless steel, the Fe-based composite coatings reinforced by spherical WC particles using plasma transferred arc were prepared by adding mass fraction 30% and 60% WC to the Fe-based composite powder, and coated on 304 stainless steel. The microstructure, phase compositions, and microhardness of coatings were determined. At a load of 50 N and a sliding speed of 20 mm/s, dry sliding wear resistances of the composite coating were investigated. The results show that the presence of WC reinforced phase, Cr₇C₃hard phase and Cr-rich solution-strengthening austenite greatly increased the microhardness of the WC reinforced coatings. The microhardness of 30% WC and 60% WC coatings were HV_0.2665 and HV_0.2724, which increased by 21.1% and 31.9% as compared with the Fe-based coating, and were 3.7 and 4 times as high as that of 304 stainless steel respectively. The coefficient of friction and the wear rate were 0.59 and 2.639×10^-6 mm³·N^-1·m^-1 for 30% WC coating and 0.42 and 1.111×10^-6 mm³·N^-1·m^-1 for 60% WC coatings. And both 30% WC and 60% WC coatings presented excellent wear resistance. Adhesive and two-body abrasive wear were predominant for 30% WC coating, whereas three-body abrasion was the main wear mechanism for 60% WC coating.