激光熔覆Ni基WC涂层内铸造WC颗粒溶解特征的研究

Investigation on Dissolution Characteristics of Cast WC Particles in Ni-based WC Coating by Laser Cladding

采用激光熔覆的方法在Q235钢表面制备了WC颗粒强化的Ni基涂层,研究了铸造WC颗粒在涂层内的溶解特征。结果表明:铸造WC颗粒在涂层底部几乎完全溶解并与扩散进入的Fe发生共晶反应形成粗大的鱼骨状形貌特征M6C型碳化物;在涂层中部,铸造WC颗粒完全溶解并析出M7C3,M12C与M23C6型碳化物;在涂层边部,大部分铸造WC颗粒发生部分溶解形成3-5μm的M6C合金化反应层,保持了原有多角状结构与高硬度特征。

WC particles reinforced Ni-based coating is produced by laser cladding on the surface of Q235 steel. The dissolution characteristics of cast WC particles are investigated. The results show that the cast WC particles are dissolved almost completely in the bottom of coating, and interact with Fe from the substrate to precipitate the herringbone M6C carbides. In the center of coating, the cast WC particles are dissolved and the carbides such as M7C3, M12C and M23C6 are precipitated. At the edge of coating, most of cast WC particles are dissolved partially to form an alloyed layer identified as M6C, resulting in the preservation of polygonal and high hardness characteristics.