CARBURIZATION AND SWELLING OF CARBON-CARBON COMPOSITES BY LIQUID ALUMINIUM

摘要

Carbon will react with aluminium when under vacuum at temperature from 400°C upwards forming aluminium carbide A1_4C_3. The solubility of A1_4C_3 in molten aluminium is lower than 0,1 ppm at 800°C. Aluminium carbide is refractory and reacts with water to form aluminium hydroxyde and methane. The wettability of carbon by aluminium is observed at respectively 700, 900 and 1100°C, for vitreous carbon, graphite and pyrographite. The reaction of formation of A1_4C_3 on graphites is slow between 800-1000°C and becomes more destructive beyond 1000°C. Aluminium carbide is formed on the surface of carbon fibers embedded in a pure aluminium matrix at temperatures above 500°C. A protective layer of A1_4C_3 appears on the fibers after 16-24 hours of reaction at 600°C. Carbon rods rotating in a cryolithe melt and liquid aluminium around 1000°C, have been studied by Hollinshead and Brown. They reported linear corrosion with time and increased wear with peripheral velocity, but small changes due to porosity.