Multi-layer Coating of SiC, Al_2O_3 and Glaze on C/C Composites for Oxidation Resistance at High Temperature

摘要

In order to prevent the high temperature oxidation of C/C composites, we applied a multi-layer coating to them. First, the graded SiC layer was prepared on the C/C substrate with a pack cementation method. Second, the stress relaxation layer was coated on the graded SiC layer by sintering slurry of alumina mixed with ZrSi_2 particles. Finally, the glaze layer was deposited on the stress relaxation layer by melting slurry of Al_2O_3-CaO-K_2O-SiO_2. We obtained results that the graded SiC layer creates the stronger bonding between the C/C substrate and the above coating layer by decreasing the difference in the coefficients of thermal expansion (CTE), the stress relaxation layer prevents to the generation of channels and the glaze layer or molten oxide film protects the substrate from high temperature oxidation.