Protective glass coating for carbon-carbon composites

An oxidation-protective, self-sealing borosilicate glass (SABB) coating was deposited on a carbon-carbon composite (C/C) using a simple and low cost method. The wettability of the glass on the composite was promoted by the formation of a 5-10 mu m beta-SiC layer on the composite surface, by direct reaction of liquid silicon with the C/C. The glass coating was thermochemically stable at 1100 and 1200 degrees C and no reaction was observed between the beta-SiC modified composite surface and the SABB glass. The percentage of C/C mass loss after thermal cycling (55 hours at 1100 degrees C) did not exceed 0.6 wt%; the efficiency and the easy maintenance of the coating is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.