316不锈钢表面等离子熔敷硼化物覆层的组织与性能

Microstructure and Properties of Boride Coating on Surface of 316 Stainless Steel by Plasma Cladding

以自制Mo-Fe-B-Cr药芯焊丝为原料,采用等离子熔敷技术在316不锈钢基体表面制备硼化物覆层,研究了覆层的显微组织、硬度、耐磨和耐腐蚀性能。结果表明:硼化物覆层与基体间形成良好的冶金结合,覆层中存在厚度约100μm的渐变层,渐变层中发生了元素的相互扩散;覆层组织中γ-Fe黏结相包裹着块状硬质相Mo2FeB2和(Mo,Fe,Cr)3B2,同时枝晶状分布的黏结相间存在大量网状共晶组织(Fe,Cr)2B、(Fe,Cr)23(C,B)6;覆层的最大显微硬度达757HV,约为基体硬度的3.4倍;覆层的磨损质量损失小于基体的,覆层具有优异的耐磨性能,磨损机理为黏结相的微切削导致硬质相颗粒的脆性剥落,从而形成磨粒磨损;覆层在质量分数5%NaCl溶液中的自腐蚀电位略高于基体的,自腐蚀电流密度小于基体的,覆层具有良好的耐腐蚀性能。

The boride coating was prepared on the surface of 316 stainless steel substrate by plasma cladding technique with self-made Mo-Fe-B-Cr flux-cored wire as raw materials.The microstructure,hardness,wear resistance and corrosion resistance of the coating were studied.The results show that a good metallurgical bond was formed between boride coating and substrate.There was a gradient layer with thickness of about 100μm in the coating,and element diffusion occurred in the gradient layer.The massive hard phases of Mo2FeB2 and(Mo,Fe,Cr)3B2 in the coating was wrapped by theγ-Fe bonding phase,while there were a lot of reticulated eutectic structures of(Fe,Cr)2B and(Fe,Cr)23(C,B)6 among the bonding phase with dendritic distribution.The maximum microhardness of the coating was 757 HV,which was about 3.4 times higher than that of the substrate.The wear mass loss of the coating was less than that of the substrate,and the coating had excellent wear resistance.The wear mechanism was micro-cutting of binding phase resulting in brittle spalling of hard phase particles and the formation of abrasive wear.The free corrosion potential of the coating in 5 wt%NaCl solution was slightly higher than that of the substrate,and the free corrosion current density was less than that of the substrate,indicating that the coating had good corrosion resistance.