Oxidation Behavior from Room Temperature to 1500°C of 3D‐C/SiC Composites with Different Coatings

Abstract

A carbon‐fiber‐reinforced silicon carbide composite (3D‐C/SiC) was prepared by chemical vapor infiltration. A SiC and SiC/Si‐Zr coating were deposited on the composite to investigate the effect of different coatings on the oxidation behavior of 3D‐C/SiC composites. The 3D‐C/SiC(SiC/Si‐Zr) composite decreased in weight below 1000°C and increased in weight above 1000°C. With an increasing oxidation time, the weight loss increased greatly and the weight gain increased little. The 3D‐C/SiC(SiC) composite always decreased in weight over the full temperature range. With an increasing oxidation time, the weight loss increased rapidly below 1000°C and reached its minimum value at 1400°C. The 3D‐C/SiC(SiC/Si‐Zr) composite had a higher oxidation resistance above 1000°C, and the 3D‐C/SiC(SiC) composite had a higher oxidation resistance below 1000°C. The wider the coating cracks, the larger the maximum weight loss and the lower the temperature corresponding to the maximum weight loss. With an increasing oxidation time, the activation energy of the 3D‐C/SiC(SiC/Si‐Zr) composite increased from 96 to 138 kJ/mol, and the 3D‐C/SiC(SiC) composite increased from 130 to 180 kJ/mol.