镁合金表面APS法制备ZrB_2-ZrC基复合涂层

Preparation of ZrB_2-ZrC Based Composite Coatings on the Surface of Magnesium Alloy Through Atmospheric Plasma Spray

针对镁合金抗烧蚀性差的问题,采用高能等离子喷涂在AZ91镁合金表面引入NiCoCrAlTaY过渡层后制备复合结构陶瓷涂层.复合陶瓷抗烧蚀层结构设计为小颗粒的SiC和ZrO_2填充于大粒径的ZrB_2和ZrC颗粒周围的四组元复合结构.采用球磨机械混合的方法将平均粒径为10μm的ZrB_2和ZrC粉末及平均粒径为1μm的SiC和ZrO_2粉末混合均匀,形成1μm小颗粒的SiC和ZrO_2均匀填充于10μm粒径的ZrB_2和ZrC颗粒的混合结构粉末作为喷涂粉末,通过大气等离子喷涂方法在46.5kW功率条件下制备复合结构陶瓷涂层.研究结果表明:复合陶瓷层内部组织为小尺寸的SiC和ZrO_2填充于大粒径的ZrB2和ZrC颗粒的四组元复合结构,达到四元复合结构的设计,涂层内部颗粒发生明显的扁平化,涂层显微硬度达到1 311kgf·mm^(-2).通过X射线衍射分析发现在涂层制备过程中粉末没有发生明显的相结构改变,透射电子显微镜微区分析表明在ZrB_2和ZrC大颗粒交界处出现B_2O_5Si非晶环带玻璃相的亚稳结构,有利于抗烧蚀性的提高.

Composite ceramic coatings of ZrB2 ,ZrC,SiC and ZrO2 were prepared on the surface of AZ91 magnesium alloy, with NiCoCrA1TaY bonding coat, through atmospheric plasma spray to improve the thermal ablation resistance. Great particles of ZrB2 and ZrC surrounded with SiC and ZrO2 small particles were designed as the composite ceramic structure. ZrB2 and ZrC powders with mean particle size of 10 tim and ZrO2 and SiC powders with mean particle size of 1 μm were mixed uniformly through ball milling. The mixed powders with 10 μm ZrB2 and ZrC particles surrounded with 1 μm ZrO2 and SiC particles were selected as feed stocks to be deposited on the surface of AZ91 magnesium alloy through atmospheric plasma spray with the arc power of 46. 5 kW. It was found that the composite ceramic coatings were composed of ZrB2 and ZrC particles surrounded with ZrO2 and SiC particles which confirmed the original design. The ZrB2, ZrC, ZrO2 and SiC particles were flattened in the composite ceramic coatings. The micro-hardness of the composite ceramic coating reached 1 311 kg· mm^-2. There were no obvious phases changed during the deposition of composite ceramic coatings through XRD analysis. There were B2 O5Si metastable structures of amorphous glass phases formed in the boundaries of ZrB2 and ZrC particles surrounded with ZrO2 and SiC particles through transmission electron microscope（TEM） analysis,which would be helpful to better thermal ablation resistance.