Preparation and properties of BAS glass-ceramics based anti-oxidation coatings

Two kinds of BaO-Al₂O₃-SiO₂ (BAS) glass-ceramics with different soften points and thermal expansion coefficients were employed to prepare three kinds of gradient coatings for carbon fiber reinforced silicon carbide(C_f/SiC) composite. These coatings were fabricated with slurry deposition combined dipping method and multi-co-firing technology. These BAS glass-ceramics based coatings were integrated and defect-free. The coatings and the composites bind tightly, which can improve the anti-oxidation performance of the coated C_f/SiC composite. All coating systems can protect C_f/SiC composite from oxidation. The graded coatings protect C_f/SiC composite markedly, and the mass loss rate and mass loss of coated composites are reduced greatly within 1200~1350 ℃. Compared with uncoated composite, the mass loss of the coated composite is reduced by 1/2~2/3, and the reminant bending strength is enhanced 7~15 times after 600 thermal shock cycles in the experimental range.