Antioxidant modification of C/C composites by in situ hydrothermally synthesized 4ZnO•B2O3•H2O

Antioxidant modification of carbon/carbon (C/C) composites by in situ hydrothermally synthesized 4ZnO center dot B2O3 center dot H2O was successfully achieved. Samples were characterized by X-ray diffraction, scanning electron microscopy, isothermal oxidation test and thermogravimetry/differential scanning calorimetry. The influence of hydrothermal temperature on the phase composition and microstructure of as-prepared 4ZnO center dot B2O3 center dot H2O, and the antioxidant modification of C/C composites were investigated. Results showed that 4ZnO center dot B2O3 center dot H2O crystallite coating was achieved on the surface of C/C composites at the hydrothermal temperature range of 100-180 degrees C. A smooth and crack-free 4ZnO center dot B2O3 center dot H2O layer was obtained when the hydrothermal temperature reached 140 degrees C. The isothermal oxidation test showed that the oxidation resistance of C/C composites was improved. The as-modified composites exhibited a weight loss of only 1.93 g/cm(3) after oxidation at 600 degrees C for 15 h, while the non-modified one had a weight loss of 5.20 g/cm(3) after only 10 h of oxidation.