气体流量对铝合金表面等离子喷涂8YSZ热防护涂层微观特性及力学性能影响研究

为了突破铝合金表面等离子喷涂热防护涂层结合强度低的技术瓶颈，采用三阴极等离子喷涂系统，在7A04-T6超高强铝合金基材表面制备了8YSZ热防护涂层，借助扫描电镜、X射线衍射仪、显微硬度计及万能力学试验机，分析表征了不同气体流量参数对涂层显微形貌、物相组成、显微硬度及结合强度的影响，并提出了气体流量参数对涂层结合强度影响的临界值。研究结果表明：不同的气体流量参数下制备的涂层上表面均存在着熔融及半熔融的粉末粒子形貌、不同尺寸的孔隙结构及不同程度的裂纹扩展形貌。伴随着气体流量的增加，涂层的致密度增加，涂层的夯实形貌则呈现先增加后减少的变化趋势。不同气体流量参数下制备的涂层的物相结构与喂料粉末基本一致，都仅存在单一成分的Zr0.92Y0.08O1.96组元。伴随着气体流量参数的增大，涂层的平均显微硬度呈现逐渐增大的变化趋势，涂层的平均结合强度呈现先增大后减小的变化趋势。

Effect of gas flow parameters on the microscopic characteristics and mechanical properties of 8YSZ thermal protective coating prepared by plasma spraying on the surface of aluminum alloy

To break through the technical bottleneck of low bonding strength of thermal protective coatings prepared by plasma spraying on aluminum alloy surfaces, a three-cathode plasma spraying system was used to prepare 8YSZ thermal protective coatings on the surface of 7A04-T6 ultra high strength aluminum alloy. With the help of scanning electron microscope, X-ray diffractometer, microhardness tester and universal testing machine, the effects of different gas flow parameters on the micromorphology, phase composition, microhardness and bonding strength of the coatings were analyzed and characterized. Finally, the critical value of the influence of gas flow parameters on the bonding strength of the coating was proposed. The results showed that the upper surface of the coatings prepared under different gas flow parameters all had molten and semi- molten powder particle morphology, pore structure and crack propagation morphology. With the increase of gas flow, the density of the coating increased, and the tamped morphology of the coating showed a trend of increasing first and then decreasing. The phase structure of the coating prepared under different gas flow parameters was basically consistent with the feed powder, and there was only a single component of Zr0.92Y0.08O1.96. With the increase of gas flow parameters, the average microhardness of the coating showed a gradually increasing trend. With the increase of gas flow parameters, the average bonding strength of the coating showed a trend of increasing first and then decreasing.