中文摘要：

采用激光熔覆技术,在20Cr基体上熔覆了硬度较高的Ni60＋35WC-Ni耐磨涂层,并与Ni60涂层进行比较。采用扫描电子显微镜（SEM）、能谱分析仪（EDS）和X射线衍射分析仪（XRD）对涂层的微观组织、元素成分和物相进行了表征分析,测试了涂层沿深度方向上的显微硬度,在20和300℃条件下进行了点接触干滑动摩擦磨损试验,并利用SEM和EDS对磨损表面进行微观组织和元素成分分析。结果表明：Ni60＋35WC-Ni涂层所含物相主要包括Fe-Ni,Cr7C3和WC,硬质相WC和Cr7C3有利于提高涂层的硬度和耐磨性。Ni60＋35WC-Ni涂层的平均显微硬度约为基体平均硬度的3倍。与Ni60涂层相比,Ni60＋35WC-Ni涂层的平均硬度较高,且其中含有硬质相WC,磨损量较小。在相同温度条件下,Ni60＋35WC-Ni和Ni60两种涂层的摩擦系数相差不大。对于同一涂层而言,300℃时涂层的摩擦系数明显低于20℃下的摩擦系数,但磨损量随温度增加而增加。

英文摘要：

Ni60 ＋ 35WC-Ni self-fluxing alloy coating with high hardness and wear resistance was prepared on 20Cr substrate by laser cladding and compared with Ni60 coating. The mierostructure, elemental composition and phase constitution of the coatings were ob- served and analyzed through scanning electron microscope （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. Microhardness distribution from substrate to coating was tested, and ball-on-disc dry sliding wear test on the coatings was per- formed at 20 and 300° C. The morphology and composition of the worn surface were observed through SEM and EDS. The results showed that Ni60 ＋ 35WC-Ni coating mainly contained phases of Fe-Ni, Cr7C3 and WC. The hard phases of WC and Cr7 C3 were bene- ficial to the hardness and wear resistance of the coating. The average microhardness of Ni60 ＋ 35WC-Ni coating was about three times that of 20Cr substrate. Compared with Ni60 coating, the average microhardness of Ni60 ＋ 35WC-Ni coating was higher and contained hard phase of WC which contributed to the lower wear loss. At the same temperature, the friction coefficients of Ni60 ＋ 35WC-Ni and Ni60 coatings were close. For both coatings, the friction eoefficients at 300 ℃ were obviously lower than those at 20 ℃, but the wear losses inereased with the temperature increasing.