Gadolinium Zirconate/YSZ Thermal Barrier Coatings: Plasma Spraying, Microstructure, and Thermal Cycling Behavior
Gadolinium Zirconate/YSZ Thermal Barrier Coatings: Plasma Spraying, Microstructure, and Thermal Cycling Behavior
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DOI：
10.1111/jace.13204
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发表时间：
2014-12-01
影响因子：
3.9
通讯作者：
Vassen, Robert
中科院分区：
文献类型：
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作者：
Bakan, Emine;Mack, Daniel E.;Vassen, Robert
由于氧化镓和氧化锆的蒸气压不同，采用大气等离子喷涂(APS)制备Gd2Zr2O7是一项具有挑战性的工作。氧化镓的挥发程度比氧化锆更大，涂层成分偏离初始化学计量比是不利的。针对化学计量比涂层，用TriplexPro等离子体炬在不同的电流水平下进行了APS实验。粒子诊断被证明是一种有效的工具，可以通过测量这些不同电流水平下的粒子温度来检测蒸发的潜在程度。采用优化的Gd2Zr2O7气孔率和化学计量比喷涂工艺制备了双层热障涂层，其底层为氧化钇稳定的氧化锆(7YSZ)。作为对比，在Gd2Zr2O7沉积过程中，也以相对较大的炬电流沉积了双层膜，这导致了相当大的蒸发量和相对较低的孔隙率。这些涂层在表面温度为1400摄氏度的热循环试验台上进行了测试。与标准的7YSZ涂层相比，采用优化的Gd2Zr2O7喷涂工艺制备的双层涂层表现出很好的热循环性能，而其他涂层则表现出早期失效。此外，还观察到了不同的失效模式：长寿命的涂层失效是由于TGO的生长，而早期失效的涂层是通过7YSZ层上部的裂纹扩展而剥落的。
Processing of Gd2Zr2O7 by atmospheric plasma spraying (APS) is challenging due to the difference in vapor pressure between gadolinia and zirconia. Gadolinia is volatilized to a greater extent than zirconia and the coating composition unfavorably deviates from the initial stoichiometry. Aiming at stoichiometric coatings, APS experiments were performed with a TriplexPro plasma torch at different current levels. Particle diagnostics proved to be an effective tool for the detection of potential degrees of evaporation via particle temperature measurements at these varied current levels. Optimized spray parameters for Gd2Zr2O7 in terms of porosity and stoichiometry were used to produce double-layer TBCs with an underlying yttria-stabilized zirconia (7YSZ) layer. For comparison, double layers were also deposited with relatively high torch currents during Gd2Zr2O7 deposition, which led to a considerable amount of evaporation and relatively low porosities. These coatings were tested in thermal cycling rigs at 1400 degrees C surface temperature. Double layers manufactured with optimized Gd2Zr2O7 spray parameters revealed very good thermal cycling performance in comparison to standard 7YSZ coatings, whereas the others showed early failures. Furthermore, different failure modes were observed; coatings with long lifetime failed due to TGO growth, while the coatings displaying early failures spalled through crack propagation in the upper part of the 7YSZ layer.