Oxidation protective multilayer coatings for carbon-carbon composites

An oxidation protective double layered coating was deposited on a carbon-carbon composite (C/C) using a simple and low cost method. A surface modification of the C/C was obtained by direct reaction of liquid silicon with the C/C, promoting the formation of a 5-10 μm β-SiC layer on the composite surface. The inner layer, in contact with the C/C, is a composite made with a barium borosilicate glass matrix (SABB) and boron carbide particles; the outer layer is another composite layer formed by a SABB glass matrix and yttrium oxide particles. The layers are deposited by a slurry technique. Oxidation tests were carried out in a furnace in air, in order to verify the coating stability and its effectiveness. No mass loss of the C/C composite was observed after 100 h at 1200°C, while after 150 h at 1300°C the C/C mass loss did not exceed 1%.