Microstructure and properties of WC-12Co composite coatings prepared by laser cladding

激光熔覆制备WC-12Co复合涂层的显微组织和性能

A comprehensive study of the phase composition, microstructure evolution, microhardness and wear performance of WC-12 Co composite coatings fabricated by laser cladding using coaxial powder-feed mode was presented. It was shown that a combination of high scan speed and high laser energy density made WC on the edge of WC-12 Co composite powders partially melt in liquid Co and 304 stainless steel matrix, and then new carbides consisting of lamellar WC and herringbone M3 W3 C(M=Fe,Co) were formed. Meanwhile, WC-12 Co composite coatings with no porosity, cracks and drawbacks like decarburization were obtained, showing high densification and good metallurgical bonding with the substrate. Furthermore, a considerably high microhardness of HV0.3 1500-1600, low coefficient of friction of 0.55 and wear rate of(2.15±0.31)×10-7 mm3/(N·m) were achieved owing to the synergistic effect of excellent metallurgical bonding and fine microstructures of composite coating under laser power of 1500 W.

采用同轴送粉激光熔覆工艺制备WC-12Co复合涂层,并对涂层的相组成、显微组织演变、硬度和磨损性能进行综合研究。结果表明:在高扫描速率和高激光能量密度综合作用下,WC-12Co复合粉末边缘的WC部分溶解于液态Co和304不锈钢基体中,形成层片状WC和鱼骨状新型碳化物M3W3C(M=Fe,Co)。所得WC-12Co复合涂层致密化程度高,与基体形成良好的冶金结合,未出现气孔、裂纹和脱碳等缺陷。此外,当激光功率为1500 W时,在良好冶金结合与精细显微组织的综合作用下涂层的维氏硬度和耐磨性能显著提高,硬度达HV0.3 1500~HV0.3 1600,涂层的摩擦因数和磨损率较低,分别为0.55和(2.15±0.3 1)×10-7mm3/(N·m)。