超细粉末低温超音速火焰喷涂WC-10Co-4Cr涂层及其干摩擦磨损性能  

Dry Tribological Performance of WC-10Co-4Cr Coating Prepared by Low Temperature High Velocity Oxygen-Fuel Flame with Ultra-Fine Powders

作　　者：李运初 邓春明 韩滔[1,2] 刘敏 

机构地区：[1]广东省新材料研究所现代材料表面工程技术国家工程实验室广东省现代表面工程技术重点实验室,广东广州510651 [2]华南理工大学材料科学与工程学院,广东广州510640

出　　处：《材料保护》2016年第9期15-18,6-7,共4页Materials Protection

基　　金：国家科技支撑项目(2014BAF08B03);广东省科技计划项目(2015B070701024);科技部科研院所项目(2014EG115005);广东省省院平台建设项目(2016GDASPT-0206和2016GDASPT-0317)资助

摘　　要：为了进一步提高超细粉末WC喷涂层的性能,以5~15μm的超细WC-10Co-4Cr粉末为材料,分别采用低温超音速火焰喷涂(LT-HVOF)和超音速火焰喷涂(HVOF)技术在316L不锈钢表面制备WC涂层。通过聚焦离子束(Focused ion beam,FIB)对WC-10Co-4Cr粒子剖面形貌进行了原位切割并分析,利用SEM形貌、EDS谱和摩擦磨损试验对涂层的显微结构和干摩擦磨损性能进行了表征。结果表明:HVOF的高焰流温度使超细WC-10Co-4Cr粉末的粘结相充分熔融,WC硬质相溶于粘结相或发生脱碳,形成Cox(WC)y脆性相和W2C相,另外因Cr较低的表面张力使涂层内界面存在富Cr带,而LT-HVOF涂层没有富Cr带;LT-HVOF涂层的摩擦系数和磨损率分别为0.632 2,1.560×10-5mm3/(N·m),均低于HVOF涂层;2种WC涂层的磨损形式均以磨粒磨损为主,HVOF涂层中的富Cr带在载荷作用下形成裂纹并易于沿其扩展,造成涂层较大块剥落,降低了WC涂层的耐磨性能。WC-10Co-4Cr splats and coatings were prepared by low temperature high velocity oxygen-fuel flame(LT-HVOF) and high velocity oxygen-fuel flame(HVOF) technology with 5-15 μm ultrafine powders as feedstock.Focused ion beam(FIB) was used to in situ cut and analyze cross section of WC-10Co-4Cr splats.Subsequently,the microstructure and dry tribological performance of WC-10Co-4Cr coatings were characterized by SEM,EDS and wear tester,respectively.Results show that the high flame temperature of HVOF process led to the sufficient melting of the binder phase in ultrafine WC-10Co-4Cr,which resulted in decarhurization of WC hard phase or dissolution of hard phase into binder to form Co_x(WC)_y and W_2 C brittle phase.Otherwise,Cr-rich strip was formed at the interface in HVOF coating due to the low surface tension of Cr melting,while Cr-rich strip was not observed in LT-HVOF coatings.Tribological coefficient and mass loss of LT-HVOF coating(friction coefficient of 0.632 2,wear rate of 1.560 × 10^(-5) mm/(N·m)) were lower than those of HVOF coating.Wear mechanisms of both WC coatings were governed by abrasive wear.In the HVOF coating,the cracks were initiated at and spread along Cr-rich strip,which caused serious coating spallation and worsened wear resistance of coating.

关 键 词：超细WC-10Co-4Cr粉末 LT—HVOF HVOF 耐磨性能 富Cr带 316L不锈钢 

分 类 号：TG174.4[金属学及工艺—金属表面处理]