为了延长磷酸反应槽内搅拌桨叶片的服役寿命, 采用激光熔覆技术在904L不锈钢表面制备出Y203/Al2O3/904L复合涂层。采用X射线衍射仪、扫描电子显微镜、金相显微镜、显微硬度计及电化学工作站对涂层相结构、显微组织、硬度及耐蚀性进行检测。实验结果表明, 激光熔覆过程中大量的Al2O3在涂层表面聚集。复合涂层主要由单一的面心立方(FCC)相组成。复合涂层与基材良好冶金结合, 其组织由底部到顶部依次为平面晶→胞状晶→柱状树枝晶→等轴晶。复合涂层的硬度为250 HV左右, 与基材相比, 大约提高了35%。复合涂层的自腐蚀电位较基材更“正”, 自腐蚀电流密度较基材更小, 耐腐蚀性能良好。

In order to prolong the service life of agitator blades inphosphoric acid reactors, the 904L-Y203-Al2O3composite alloy coating was fabricated by laser cladding on 904L stainless steel. The X-ray diffraction, scanning electron microscope, optical microscope, microhardness and electrochemical workstation were used to measure phase structure, microstructure, microhardness and corrosion resistance of coating. The experimental results show that an amount of aluminum oxide (Al2O3) couldn′t be dissolved into the coating. The coating is consisted of single face-centered-cubic (FCC) phase. Excellent metallurgical bonding between the coating and substrate is found.From the bottom to top of coating, the microstructure is plane crystal, dendritic crystal, columnar dendrite and equiaxed grain, successively. The hardness of composite coating is about 250 HV, 35% risen than that of substrate. The composite coating exhibits outstanding corrosion resistance with more “positive”self-corrosion potential and lower self-corrosion than that of substrate.