PREPARATION AND CHARACTERIZATION OF SIC-COATED C C COMPOSITES USING PULSE CHEMICAL-VAPOR-DEPOSITION (PULSE-CVD)/

Carbon/carbon (C/C) composites were coated with SiC layers using a pre ssure-pulse chemical vapor deposition (pulse-CVD) process and then the micro-cracks present on the SiC coatings were glass-sealed. The pulse -CVD conditions of the SiC coatings were examined and optimized as fol lows: temperature of 1473 K, MTS concentration of 5 mol% and reaction hold-time 2 s. Furthermore, the oxidation resistivity and the mechanic al properties of glass-sealed SiC coatings/C/C composites were examine d at high temperatures. The SiC layers had good adherence to the C/C c omposites by the anchor locking effect. The oxidation resistivity of t he glass-sealed SiC/C/C composites was quite excellent and the weight loss after 1 h exposure in air at 1973 K was only 1.3 wt%. The tensile strength and modulus of the glass-sealed SiC/C/C composites were 610 MPa and 220 Cpa at 300 K, respectively. These values were still mainta ined after 1 h exposure in air at 1873 K.