Ni-65WC粉末的雾化造粒与激光熔覆层组织和冲蚀性能研究

Research on Microstructure and Erosion Properties of Atomization Granulation and Laser Cladding Coating of Ni-65WC Powder

为提高煤炭开采、洗选和煤化工的煤机装备耐冲蚀性能,利用雾化造粒和激光熔覆技术制备高WC含量Ni/WC复合熔覆层,通过组织观察、力学性能检测、腐蚀及磨损实验对比研究了雾化造粒和激光熔覆过程中Ni/WC复合熔覆层的组织、结构演变,并基于射流式冲蚀分析了材料的冲蚀行为。结果表明:喷雾干燥Ni/WC团聚复合粉末的球形度与粘结剂含量成正比,而粒径则与雾化器转速成反比。激光熔覆后,Ni/WC熔覆层由Ni、WC和W_(2)C相组成。其中,在熔覆过程中WC出现了熔解与析出变化,形成了层状共晶→棒状、针状→块状结构的富W和富Ni相。在冲蚀磨损工况下,WC有效改善了Ni/WC熔覆层冲刷磨损性能,磨损率为0.097 g/(m^(2)·h),相比Q235A钢降低约23%。此时,细小的WC均匀镶嵌在磨损表面的粘结相中起到强化作用。同时,Ni/WC熔覆层的剥落处表现出明显的塑性特征,为典型的韧性破坏。

In order to improve the erosion resistance of coal machinery and equipment involved in coal development, coal washing and coal chemical industry, Ni/WC composite coatings with high WC content were prepared by atomization granulation and laser cladding. The evolution of microstructure of Ni/WC composite coatings in the process of atomization granulation and laser cladding was studied, and the erosion behavior of Ni/WC composite coating was analyzed based on jet erosion. The results show that the sphericity of atomization granulation Ni/WC composite powder was directly proportional to the contents of binder. Then, the laser cladding Ni/WC coating were consisted of Ni, WC and W_(2) C phases. During laser cladding, the W and Ni rich phases with the structure of lamellar eutectic rod, needle and block structure were formed by the dissolution and precipitation of WC in the process of cladding. Under the condition of erosion wear, the wear rate of Ni/WC cladding coating was 0.097 g/(m^(2)·h), which was about 23% lower than that of Q235 A. The erosion wear performance of Ni/WC cladding layer was effectively improve by WC particles, owning to fact that the fine WC was embedded in the bonding phase on the worn surface and plays a strengthening role during erosion wear. At the same time, the spalling area showed obvious plastic characteristics and typical ductile failure characteristics.