用激光束在4Cr13钢基体上熔覆ZrO2与Ni合金的混合粉末, 形成了分层结构的复合涂层, 即表面为致密的ZrO2陶瓷层.介于陶瓷层与基体之间的是Ni基合金过渡层。组织分析表明, ZrO2层的上部为等轴晶, 中下部为柱状晶, 主要由t＇-ZrO2相及少量沿t＇晶界分布的m-ZrO2相组成；Ni合金结合带呈现出树枝晶及其晶间共晶的单一凝固组织。该复合涂层的分层机制可解释为互不混溶的ZrO2与Ni合金熔珠在界面张力和浮力作用下发生离析重排, 再各自重新凝固。

Using a laser to clad a mixture POwder of 60 V. -% ZrO2 plus 40 V.-% Nialloy preplaced on steel 4Cr13 substrate, a comPOSite coating that consists of a pure Zro2layer at the upper region and a Ni-alloy bonding zone adjacent to the substrate is formed. The microstructural analyses reveal that the ZrO2layer exhibits equiaxed grains at the upper part and a columnar structure at the lower part and is comPOsed of t-ZrO2 Phase and 2. 9% m-ZrO2 phase distributed along the t boundary. The bonding zone presents an even solidification microstructure composed of Ni-based dendrites and interdendritic eutectics. The stratification mechanism of the composite coating is interpreted as that the insoluble melts of ZrO2 and Ni-alloy powders undergo a redistribution before solidification due to density difference and interfacial tension between these two liquid phases, and then resolidify separately.