【目的】常规大气等离子喷涂制备新型热障涂层陶瓷层候选材料Ba(Mg1/3Ta2/3)O3(BMT)涂层应变容限较低。【方法】基于悬浮液等离子喷涂技术(SPS),以乙醇为分散介质,聚丙烯酸(PAA)、聚乙烯亚胺(PEI)和聚乙二醇(PEG)为分散剂,借助机械球磨制备了不同成分配比的BMT悬浮液。通过重力沉降观察法、紫外-可见分光光度计、Zeta电位仪对悬浮液的分散行为进行了研究,分析了分散剂种类及添加量对BMT悬浮液稳定性的影响;并利用SPS沉积了BMT涂层,对涂层的物相结构、表面形貌和截面组织进行了表征分析。【结果】结果表明:分散剂PEI在BMT颗粒表面吸附能够提高其Zeta电位,增强颗粒间斥力,并提供空间位阻作用,相比PAA和PEG,BMT悬浮液可以获得更好的分散效果。同时,添加PEI的BMT悬浮液黏度较低(介于1.5~2mPa·s),适用于SPS.由SPS制备的BMT涂层基本维持了BMT的物相结构,涂层呈现明显的柱状晶组织,且随悬浮液固含量的提高,涂层沉积效率增加,所形成的柱状晶体积更大,符合高应变容限涂层的组织结构特征。

【Purposes】 The strain tolerance of Ba(Mg1/3Ta2/3)O3  (BMT) thermal barrier coat- ing prepared by conventional atmospheric plasma spraying is low. 【Methods】 With suspension plasma spraying (SPS), BMT suspensions with different compositions are prepared by mechani- cal ball grinding with ethanol as the dispersion medium and polyacrylic acid (PAA), polyethyle- neimine (PEI), and polyethylene glycol (PEG) as dispersants. The dispersion behavior of BMT suspension was studied through gravity sedimentation observation method, UV-Vis spectropho- tometry, and Zeta potentiometry. The effects of dispersant type and content on the stability of BMT suspension were analyzed. The BMT coating was deposited by SPS, and the phase struc- ture, surface morphology, and cross-section microstructure of the BMT coating were character- ized and analyzed. 【Findings】 The results show that the adsorption of the dispersant PEI on the surface of the BMT particles improves their Zeta potential, enhances the repulsive force between particles, and provides a steric hindrance, which results the better dispersion of BMT suspension with PEI dispersant than that with PAA and PEG. In addition, the BMT suspension with PEI has a low viscosity (1.5-2 mPa·s), making it appropriate for SPS. The coating prepared by SPS essentially preserves the BMT phase structure, and shows a clear columnar-crystal microstruc- ture. With the increases of the solid content in the suspension, the deposition efficiency of the BMT coating increase, and the volume of columnar crystals formed becomes larger, which con- forms to the microstructural characteristics of high strain tolerance coatings.