碳/碳化硅复合材料上莫来石涂层的制备及氧化行为

PREPARATION AND ANTI-OXIDATION BEHAVIOR OF MULLITE COATING ON CARBON/SILICON CARBIDE COMPOSITE

以正硅酸乙酯[(C2H5)4SiO4,ethyl orthosilicate,TEOS]和硝酸铝[Al(NO3)3.9H2O]为原料,制备了莫来石(3Al2O3.2SiO2,mullite)溶胶,用浸涂法在碳/碳化硅(Cf/SiC,下角f表示纤维,下同)上制备3Al2O3.2SiO2涂层(mullitecoating,MC)。对Cf/SiC和Cf/SiCMC进行了等温-氧化实验,并研究了两者的氧化规律。结果表明:Cf/SiC和Cf/SiCMC的氧化都可以划分为3个主要阶段:θ<700℃;700℃<θ<1000℃;1000℃<θ<1200℃。在各个阶段,控制氧化速率的机理各有不同,Cf/SiCMC的氧化质量损失比Cf/SiC的低50%左右,表现出较好的抗氧化性能。

Ethyl orthosilicate （TEOS） and aluminum nitrate were used as raw materials for preparation of mullite sol. The mullite coating （MC） on carbon/silicon carbide （Cf/SiC, f refers to fiber, the same below） was prepared by the dip coating method. Isothermal oxidation tests were performed on Cf/SiC and Cf/SiC MC and their oxidation behaviors were studied. The results show that the oxidation of Cf/SiC and Cf/SiC MC can be divided into three main stages： θ〈700 ℃, 700 ℃〈θ〈1 000 ℃, 1 000 ℃〈θ〈1200 ℃. The oxidation rate-determining steps for each stage are different; the mass loss percentage of the Cf/SiC MC was fifty percent lower than that of the Cf/SiC. The Cf/SiC MC has good oxidation resistance.