摘要：
设计30wt%~70wt%不同Mo含量的Mo-Ni混合粉末,通过添加少量ZrO2形成梯度复合合金粉末,采用激光直接沉积技术在3Cr2W8V钢板上制备Mo-Ni-ZrO2高温耐磨复合合金梯度涂层.利用金相显微镜、显微硬度计、SEM、能谱仪及XRD等对制备梯度涂层的组织结构、裂纹与气孔消除、相组成及其硬度等进行了研究.结果表明:在Mo-Ni系复合合金梯度涂层中,由于Mo在激光作用下易氧化为MoO3,MoO3受热易挥发,在熔池中未能及时逸出,因此,涂层在50wt%Mo梯度层处开始出现裂纹和气孔,其显微硬度平均值为287.29;在Mo-Ni-ZrO2系梯度涂层中,添加ZrO2后,50wt%Mo梯度层处的裂纹和气孔明显减少,该涂层中主相为MoNi及强化相Mo1.24 Ni0.76、Ni3 Zr,还有少量MoO3,其显微硬度平均值为477;ZrO2具有良好的消除Mo-Ni高温复合合金梯度涂层裂纹气孔缺陷与增强梯度涂层硬度的作用.%The gradient composite Mo-Ni alloy powder with the different contents of 30-70wt%Mo and a small a-mount of ZrO2 were designed,the Mo-Ni-ZrO2 high temperature wear-resistant composite alloy coating were pre-pared on 3Cr2W8V steel by laser direct deposition technology.The microstructure,crack and pore elimination, phase composition and hardness of gradient coatings were studied by optical microscope,micro hardness tester, SEM,energy dispersive spectrometer and XRD.The results show that the MoO3 is formed in the Mo-Ni composite alloy gradient coating because molybdenum is easily oxided under the laser action,MoO3 tends to volatile when it's heated and can't escape timely in laser molten pool,so as to cracks and pores are produced in the gradient layer with 50wt%Mo,and its average microhardness is 287.The cracks and pores are reduced obviously because of ZrO2 addi-tion in Mo-Ni-ZrO2 gradient layer with 50wt%Mo,the phase of the Mo-Ni-ZrO2 gradient layer is composed of MoNi and reinforced such as Mo1.24 Ni0.76 ,Ni3 Zr and a small amount of MoO3 ,its average microhardness is 477.ZrO2 has a favorable effect on elimination of the cracks and pores and improvement of the hardness in Mo-Ni high temperature gradient composite alloy coating.
