ZrB2 particles reinforced glass coating for oxidation protection of carbon/carbon composites

Abstract

A dense ZrB2 particles reinforced glass (ZrB2/SiO2) coating was prepared on the SiC coated carbon/carbon composites by a facile sol-dipping approach. The prepared ZrB2/SiO2 coating could protect the composites from being oxidized for 160 h at 1773 K with a weight loss of 6.9 mg/cm2. The flexural strength retention ratio of the ZrB2/SiO2 coated composites is 87% after oxidation for 160 h at 1773 K. The continuous SiO2 glass layer embedded with the submicron ZrSiO4 particles was formed during oxidation. This was helpful to lower the diffusion rate of oxygen and improve the stability of SiO2 glass film, thus improving the oxidation resistance of the coated samples. After thermal cycles between 1773 K and room temperature for 15 times, penetrated cracks formed in the coating. The weight loss of the ZrB2/SiO2 coated sample presented linear relationship, and the final weight loss per unit area was 6.35 mg/cm2. The generation of the penetrative cracks and the debonded coating interface resulted in the failure of the ZrB2/SiO2 coating.