以Y2O3粉和硅树脂配制成的浆料为原料,通过浸涂提拉法在C/SiC复合材料表面制备Y2Si2O7涂层,研究Y 2 Si 2 O 7相的合成、涂层结构和氧化保护效果以及抗氧化机制.结果表明,质量比为54.2:45.8的Y 2 O 3粉/硅树脂混合物先在800℃空气中裂解再在1400℃ Ar惰性气氛下热处理,能够完全转化成Y2Si2O7.Y2Si2O7涂层致密度高且与基体结合紧密,在氧化过程中发生进一步致密化而呈现出优异的抗氧化性能,分别在1400、1500和1600℃氧化30 min后,复合材料的强度保留率达到130%~140%.此外,在1500℃下Y2Si2O7涂层会与氧化铝支撑体之间发生反应,生成具有低共熔点的Y?Si?Al?O玻璃相.
Yttrium silicate (Y2Si2O7) coating was fabricated on C/SiC composites through dip-coating with silicone resin + Y2O3 powder slurry as raw materials. The synthesis, microstructure and oxidation resistance and the anti-oxidation mechanism of Y2Si2O7 coating were investigated. Y2Si2O7 can be synthesized by the pyrolysis of Y2O3 powder filled silicone resin at mass ratio of 54.2:45.8 and 800 ℃ in air and then heat treated at 1400 ℃ under Ar. The as-fabricated coating shows high density and favorable bonding to C/SiC composites. After oxidation in air at 1400, 1500 and 1600 ℃ for 30 min, the coating-containing composites possess 130%?140% of original flexural strength. The desirable thermal stability and the further densification of coating during oxidation are responsible for the excellent oxidation resistance. In addition, the formation of eutectic Y?Si?Al?O glassy phase between Y2Si2O7 and Al2O3 sample bracket at 1500 ℃ is discovered.
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