目的 研究大面积可重复使用刚性陶瓷瓦表面高辐射率硼硅玻璃涂层在服役温度条件下微观组织的演变情况。方法 采用在1250 ℃和1300 ℃下热暴露的方法来模拟涂层服役温度环境，借此研究涂层微观组织高温下的演变规律。采用扫描电子显微镜（SEM）对热暴露前后涂层的微观形貌进行了表征，利用X射线衍射仪（XRD）表征了涂层热暴露前后的物相组成。结果1250 ℃和1300 ℃热暴露之后，涂层表面出现微孔，尤其在辐射剂颗粒（MoSi2、SiB4）聚集区域，且微孔数量随热暴露次数的增加而增多。1300 ℃下热暴露5次后，中间过渡层发生烧结分层现象，靠近表面一侧逐渐变致密并与表面层烧结在一起，而另一侧则逐渐和基体烧结在一起。涂层热暴露后有方石英相析出，且析晶量与热暴露次数呈正相关关系。 结论1300 ℃下热暴露后，中间过渡层逐渐破坏，涂层由双层结构转变为单层结构，其抗热震性能下降，易产生裂纹、脱落等问题。高温热暴露析出方石英晶体将会影响涂层尺寸的稳定性。此外，高温热暴露导致涂层中辐射剂成分氧化，生成微孔，破坏涂层致密性，降低其抗冲刷能力，更易引起涂层脱落。

The work aims to study the microstructure evolution of high emissivity borosilicate coating on large area reusable rigid insulation tile in the ascent temperature environment. Thermal exposure was carried out to simulate the temperature condition of reentry at 1250 ℃ and 1300 ℃, so as to investigate the evolution rules of coating microstructure at high temperature. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD were respectively used to characterize the microstructure and the phase of coating before and after thermal exposure. The coating surface generated micropores after thermal exposure at 1250 ℃ and 1300 ℃, especially in the zone of radiation agent particle (MoSi2 and SiB4) aggregation. The number of micropores increased with the number of thermal exposure. In addition, intermediate transition layer was re-sintered and stratified after 5 times of thermal exposure at 1300 ℃. The side near surface gradually became dense and was sintered together with the surface, while the other side was sintered with the substrate. Cristobalite phase precipitated on the coating after thermal exposure and the amount of crystallization was positively correlated with the number of thermal exposures. The intermediate transition layer is gradually destroyed and the structure of coating is also transformed from a two-layer to a single-layer after thermal exposure at 1300 ℃. The capability of thermal shock resistance decreases and the coating is easy to cause crack, peeling, etc. The cristobalite precipitated on the coating after thermal exposure will affect the size and stability of coating. The thermal exposure can cause oxidation of the radiation component and form micropores, which reduce the compactness of surface coating and lead to the peeling of coating.