超音速火焰喷涂WC-MoCoB涂层的制备和性能研究

Preparation and Properties of WC-MoCoB Coating by High-velocity Oxygen-fuel Spraying

本文主要在初始WC-Co体系中加入Mo和B4C粉末,采用球磨混料-喷涂造粒-真空烧结技术制备出含有三元硼化物的热喷涂粉体,通过超音速火焰(HVOF)喷涂工艺制备出WC-MoCoB涂层。采用扫描电子显微镜、硬度计、压痕仪、X射线衍射和滑动磨损试验表征了涂层的微观结构、力学性能、物相组成以及滑动磨损性能。结果表明:与常规WC-Co涂层相比,WC-MoCoB涂层具有低孔隙、结合致密的微观结构;涂层的硬度分布稳定性、弹性模量和断裂韧性均得到了提高。WC-MoCoB涂层滑动磨损性能的增强主要体现在更低的摩擦系数和显著降低的磨损率;同时提高的塑性变形极限和对微犁切削的抑制作用、增强的界面结合和改善的力学性能均对磨损过程起到了关键作用,有效地抵抗了磨损。

In this paper,Mo and B4C powders are added to the initial WC-Co system,and the thermal spray powder containing ternary boride is prepared by ball milling mixture-spray granulation-vacuum sintering technology.Meanwhile,WC-MoCoB coating is prepared by the high-velocity oxygen-fuel(HVOF)spray process.The microstructure,mechanical properties,phase composition and friction and wear properties of the coating were characterized by SEM,hardness tester,indentation tester,X-ray diffraction and sliding wear test.The results show that WC-MoCoB coating with low porosity and compact microstructure;the hardness distribution stability;elastic modulus and fracture toughness of the coating have been improved compared with conventional WC-Co coating.The enhancement of the sliding wear performance of WC-MoCoB coating is mainly reflected in the lower friction coefficient and significantly reduced wear rate.At the same time,the increased plastic deformation limitation,the inhibition of microplow cutting,the enhanced interface combination and improved mechanical properties all play a key role in the wear process which effectively resists wear.