Oxidation mechanism of SiC-Glass coating for protecting carbon/carbon composites from oxidation at high temperatures

An SiC-Glass multi-layer coating was fabricated on the carbon/carbon (C/C) composites by using the pack cementation technique and the precoating-sintering process. The as-prepared multi-layer was characterized by XRD and SEM analyses. The oxidation kinetics of the coated C/C samples was also investigated at different temperatures. The results indicate that the multi-coating is composed of two layers. The inner layer consist of β-SiC phase and a small quantity of silicon phase. The outer layer is a borosilicate glass layer modified by MoSi₂ particles. Additionally, the multi-coating has good interface bonding between the two layers. The experimental data of the oxidation tests show that the SiC-Glass coating exhibits an excellent oxidation resistance in air in the temperature range from 1300℃ to 1600℃, and the oxidation activation energy of the coated C/C is 118.1 kJ/mol. After oxidation at 1600℃ in air for 65 hours, the mass loss of the SiC-Glass coated sample is only 1.02%.