AZ91D镁合金表面激光熔覆Ni基+WC合金涂层

Laser Surface Cladding of AZ91D Magnesium Alloy with Ni-Based and WC Powders

采用激光熔覆技术在镁合金表面制备了Ni基合金+WC复合陶瓷涂层,并对不同WC含量下的复合涂层进行了成分和性能分析。研究结果表明,激光熔覆涂层与基体之间获得了良好的冶金结合;涂层主要由AlNi3,Al3Ni2金属间化合物以及Ni(Cr2O4)和多种碳化物组成;质量分数为25%WC的加入减少了涂层中孔隙和裂纹的存在,与基体相比,涂层的硬度提高了约9.4倍,弹性模量提高了约2.06倍;耐蚀性也得到了明显提高。

The laser surface cladding of AZ91D magnesium alloy with Ni-Cr-B-Si＋WC powders has been investigated. Laser surface cladding was conducted using a continuous wave CO2 laser. As a result,a good metallurgical bond interface was obtained between Mg alloy substrate and coating. The microstructure and phase analysis of the coating were carried out by scanning electron microscope （SEM） and X-ray diffraction （XRD）. The hardness and the corrosion properties of the coating were also measured. The experimental results show that the cladding layer is composed of AlNi3,Al3Ni2,Ni（Cr2O4） and different kinds of carbide. The cracks and porosity of coating are decreased with the join of 25% WC particles. The hardness of the cladding layer is significantly improved by 9.4 times higher than that of the AZ91D substrate,and the modulus is about twice higher than that of the substrate. The corrosion resistance of the laser modified samples is considerably improved as compared to the substrate.