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采用料浆喷涂法在陶瓷纤维瓦表面制备了一种新型MoSi2-Al2O3-SiO_2耐高温高发射涂层,通过控制Al2O3-SiO_2体系中SiO_2含量,对涂层热膨胀系数进行调控;通过高温灼烧实验考察涂层的耐高温性能。使用XRD、SEM和热膨胀系数测试仪对涂层物相组成、微观形貌和热膨胀系数进行表征。结果表明,本实验所制备的MoSi2-Al2O3-SiO_2涂层主要由MoSi_2、少量MoSi_2氧化产物、方石英晶相以及硅铝玻璃相构成,涂层表面致密、平整并且与多孔陶瓷纤维基体形成了紧密的结合;经过1500℃,1 h高温热处理后,涂层宏观和微观结构均没有发生明显变化;涂层的热膨胀系数可通过Al2O3-SiO_2体系中SiO_2的含量在一定范围内进行调节,当SiO_2含量由70%增加到85%(质量分数)时,涂层热膨胀系数由4.49×10~(-6) K~(-1)降低至3.45×10~(-6) K~(-1)。
A novel MoSi2-Al2O3-SiO2 high-temperature-resistant and high-emission coating was prepared on the surface of ceramic fiber tile by slurry spraying. The thermal expansion coefficient of the coating was controlled by controlling the content of SiO2 in the Al2O3-SiO2 system. Investigate the coating’s high temperature performance. The phase composition, microstructure and thermal expansion coefficient of the coatings were characterized by XRD, SEM and thermal expansion coefficient tester. The results show that the MoSi2-Al2O3-SiO2 coating prepared in this experiment is mainly composed of MoSi2, a small amount of MoSi2 oxidation products, cristobalite phase and aluminosilicate glass phase. The coating surface is dense, flat and close to the porous ceramic fiber matrix ; After 1500 ℃, 1 h high temperature heat treatment, the coating did not change the macroscopic and microscopic structure of the microstructure; Coefficient of thermal expansion of the coating can be adjusted by the content of SiO_2 in the Al2O3-SiO_2 system within a certain range, when the SiO_2 content From 70% to 85% (mass fraction), the coefficient of thermal expansion of the coating decreased from 4.49 × 10 -6 K -1 to 3.45 × 10 -6 K -1.