PREPARATION AND PERFORMANCE STUDY OF OXIDATION RESISTANT COATING ON CARBON FIBER REINFORCED CERAMIC MATRIX COMPOSITES

摘要

Carbon fiber reinforced ceramic matrix composites (CFRCMCs) have great high temperature mechanical properties and thermal properties.They are ideal thermal structure materials and environmental protection materials in aerospace field.In order to improve the anti-oxidation ablative property of the composite material,a double layer composite coating is prepared based on the slurry sintering method,with ZrB2-SiC glass as the inner layer and ZrB2-MoSi2 glass as the outer layer.The influences of coating composition and preparation technology on the microstructure and anti-ablative properties of the coating are studied,and the ablation mechanism is analyzed.Under the ablation conditions in this paper,a dense oxide layer is formed on the surface layer of the coating,which is mainly composed of Si02 glass phase and mixed with some oxide ceramic particles,such as Zr02 and ZrSi04.Because the oxygen diffusion coefficient of Si02 glass is very low,the oxide layer can play a good role in oxygen resistance and inhibit the continuous oxidation of the coating.Finally,it is proved that the addition of dispersant tetramethylammonium hydroxide (TMAH) can improve the stability and fluidity of the slurry,which provides an important prerequisite for the uniformity of composition and thickness of the coating obtained by slurry sintering.