为增强42CrMo钢表面硬度及耐磨性,利用半导体激光器在基体表面制备了质量分数分别为0、10%、20%、30%及40% nano-WC粉末的Ni60增强涂层。采用OM、SEM、EDS、XRD对试样的微观组织与相成分进行表征,利用数显显微硬度计和高温摩擦磨损试验机进行力学性能及摩擦磨损性能测试。结果表明,nano-WC增强Ni60涂层表面成形良好。增强涂层的组织形貌呈条状、树枝状、鱼骨状、块状和粒状;物相以奥氏体Ni-Fe相为主,nano-WC一部分保留下来,一部分形成了W2C新相;涂层中还生成有Cr23C6、M6C、Cr7C3复合碳化物及CrB和NiW等复杂化合物。nano-WC增强涂层的显微硬度最大可达1256 HV0.2,比Ni60合金涂层提高了约50%。增强涂层的最小磨损体积为1.29mm 3,仅为Ni60合金涂层的1/7;增强涂层平均摩擦系数可低至0.275,而Ni60合金涂层平均摩擦系数为0.530,降低了约48%。摩擦磨损研究表明nano-WC增强涂层磨损机制主要为黏着磨损,同时还伴有轻微的磨粒磨损。

In order to improve the surface hardness and wear resistance of 42CrMo steel, Ni60 reinforced coatings containing the nano-WC powder mass fractions of 0, 10%, 20%, 30%, and 40% were prepared on the surface of substrate by semiconductor laser in this paper. The microstructure and phase composition of samples were analyzed by OM, SEM, EDS, and XRD. The mechanical property and friction and wear property were tested using a digital microhardness tester and a high temperature friction and wear tester. The results show that the nano-WC reinforced Ni60 coating surface is well-formed. The microstructure of the enhanced coating is strip, dendritic, fishbone, block, and granular. The phase is dominated by austenitic Ni-Fe, part of nano-WC remains, part of W2C new phase is formed. A series of complex compounds, such as Cr23C6, M6C, Cr7C3, CrB, and NiW, are generated in the coating. The maximum microhardness of the nano-WC reinforced coating is 1256HV0.2, which is about 50% higher than that of the Ni60 alloy coating. The minimum wear volume of reinforced coating is 1.29mm 3, which is only 1/7 of Ni60 alloy coating; the average friction coefficient of the reinforced coating is as low as 0.275, while that of Ni60 alloy coating is 0.530, which decreases by about 48%. Friction and wear studies show that the wear mechanism of nano-WC reinforced coating is mainly adhesive wear, accompanying with slight abrasive wear.