Influence of solvothermal time on oxidation resistance of carbon/carbon composites modified by borate sol

Abstract

Carbon/carbon (C/C) composites were modified with a borate sol–gel precursor by a novel process integrating sol–gel and solvothermal processes in order to improve the low temperature antioxidation properties of the C/C composites. Results show that the surface of the modified composites is covered by a molten B₂O₃ layer, and the oxidation resistance of the composites is improved with the extension of solvothermal time increasing from 12 to 48 h. After oxidation at 600°C for 6 h, the oxidation rates of the modified C/C composites are gradually decreased. The mass loss of the modified C/C composites at 600°C is due to the diffusion of oxygen along the molten B₂O₃ layer and the vaporisation of a small amount of B₂O₃.