Abstract Thermal properties and microstructure characterization of Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coatings (TBCs) deposited by Air Plasma Spray (APS) onto a Ni-base superalloy (Inconel 625) were studied. Two separate sets of tests were performed. The first one consisted in Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) performed over free-standing TC samples detached from TBCs. The second one included the analysis of the cross section of samples heat treated at 1100 °C with holding times of 600, 1000, and 1700 h. The TC porosity was analyzed for different heat treatment conditions so that inter-lamellar, intra-lamellar and globular pores, as well as cracks, were identified and quantified independently. An initial porosity reduction related to inter-lamellar and intra-lamellar pores, as well as cracks, was observed during the first 600 h of heat treatment, due to sintering. However, porosity continually increased during heat treatment from 600 to 1700 h driven by volumetric changes associated to phase transformations. During this period, yttrium diffused from the metastable tetragonal phase favoring the transformation to cubic phase while monoclinic phase transformed after cooling from the yttrium-depleted tetragonal phase. Energy absorption curves and the variation of heat capacity with temperature were also determined and correlated to microstructural changes.

中文翻译：

---

通过空气等离子喷涂沉积在镍基高温合金上的氧化钇稳定氧化锆 (YSZ) 涂层的热性能和相稳定性

摘要 研究了通过空气等离子喷涂 (APS) 沉积在镍基高温合金 (Inconel 625) 上的氧化钇稳定氧化锆 (YSZ) 热障涂层 (TBC) 的热性能和微观结构特征。进行了两组独立的测试。第一个包括差示扫描量热法 (DSC) 和热重分析 (TGA)，对与 TBC 分离的独立 TC 样品进行分析。第二个包括对在 1100°C 下热处理并保持时间为 600、1000 和 1700 小时的样品横截面的分析。分析了不同热处理条件下的 TC 孔隙率，以便独立识别和量化层间、层内和球状孔隙以及裂纹。与层间和层内孔隙以及裂缝相关的初始孔隙率降低，由于烧结，在热处理的前 600 小时期间观察到。然而，在与相变相关的体积变化的驱动下，孔隙率在热处理过程中从 600 小时持续增加到 1700 小时。在此期间，钇从亚稳四方相扩散，有利于向立方相转变，而单斜相则在从贫钇四方相冷却后转变。能量吸收曲线和热容随温度的变化也被确定并与微观结构变化相关。钇从亚稳四方相扩散，有利于转变为立方相，而单斜相从贫钇四方相冷却后转变。能量吸收曲线和热容随温度的变化也被确定并与微观结构变化相关。钇从亚稳四方相扩散，有利于转变为立方相，而单斜相从贫钇四方相冷却后转变。能量吸收曲线和热容随温度的变化也被确定并与微观结构变化相关。