真空熔覆镍基合金涂层中碳化钨颗粒转变行为

The Transformation of WC in Ni-Based Alloy Coating by Vacuum Melting

以Ni60A自熔合金粉末和镍包碳化钨粉末为原料,利用真空熔覆方法在低碳钢表面制备了镍基碳化钨耐磨复合涂层。研究了真空工艺条件下,镍基合金中碳化钨颗粒的转变行为。试验结果表明,高温下保温时间延长对镍基碳化钨复合涂层的组织影响很大,WC颗粒在镍基体中发生转变,转变的主要特征是WC硬质相边缘转变为针状相,随着高温加热时间的延长,针状相组织面积扩大,转变为针状团簇结构,最终转变为粒状相。结合XRD分析,粒状相为具有复杂立方结构的Fe6W6C相,这种碳化物,显著降低了涂层的硬度。

Ni-based composite coatings reinforced with WC particulates were fabricated on Q235 steel by vacuum melting. The powders of Ni60A alloy and WC were used as raw materials. The transformation of WC particulates under the vacuum brazed processing condition was studied Results show that prolonging the melting time has great effect on the microstructure of composite coatings at high temperature and WC transformation occurs. The dominant characteristics are that it transforms into needle phase on the verge of hard phase; with the melting time prolonging, the area of needle phase enlarges and turns into needle congeries, and finally transforms into a mass of particle phase. XRD analysis indicates the particle phase is Fe6W6C with complicated cubic structure, which reduces the hardness of the coating evidently.