Cf/SiC复合材料SiC/Yb2SiO5抗氧化复合涂层研究

SiC/Yb2SiO5 Multilayer Coatings for Oxidation Protection of Cf/SiC Composites

摘要:

硅酸镱(Yb2SiO5)是Cf/SiC复合材料非常理想的抗氧化涂层材料。用脉冲CVD法在Cf/SiC复合材料上先制备SiC粘附层。用溶胶凝胶法制备粒径为200~300 nm的单相Yb2SiO5粉体，然后用PCS-SiC-Yb2SiO5浆料浸涂法制备SiC-Yb2SiO5过渡层，因PCS粘结强度大，且热解后能在原位生成SiC，故能大大增加涂层的结合力。配备低粘度、高固含量的Yb2SiO5浆料，并用浆料浸涂烧结法制备致密、细晶粒的Yb2SiO5涂层。1500 ℃静态空气中氧化实验表明：SiC/Yb2SiO5复合涂层具备优异的抗氧化性能

Abstract:

Ytterbium silicate (Yb2SiO5) is a promising oxidation protective coating material for C fiber-reinforced SiC (Cf/SiC) composites. Firstly, the SiC bond coat was prepared on Cf/SiC composites by pulse CVD. The single-phase Yb2SiO5 powders of 200~300 nm in size were synthesized by sol–gel process. Then for the first time, the SiC-Yb2SiO5 intermediate coat was applied on the SiC coated Cf/SiC composites through PCS-SiC-Yb2SiO5 slurry application. The incorporation of PCS could significantly improve the adhesion of the coating because of the great stickiness of PCS and its ability to form SiC ceramic in situ after pyrolysis. The Yb2SiO5 slurry with low viscosity and high solid content was prepared, and the dense Yb2SiO5 top coat with fine crystallites was fabricated by dip-coating and subsequent sintering. The oxidation tests at 1500 ℃ in stationary air indicate that the fabricated SiC/Yb2SiO5 multilayer coatings possess a outstanding oxidation resistance