抄録
The oxidation velocities of isotropic graphite, pyrolytic carbon, silicon- and boron-mixed graphites were measured by using a vaccum microbalance of Cahn RG-type under an oxygen pressure of 1.33 kPa (10 Torr) and a temperature range from 650 to 900°C. For isotropic graphites with different ash concentrations, it was observed that the oxidation velocity increased with higher ash concentration when the graphite temperature was below 750°C. The pyrolytic carbon had the oxidation velocity of approximately one order of magnitude smaller than that of the isotropic graphite. The oxidation velocity of silicon-mixed graphite linearly decreased with the increase of silicon concentration. In the case of the boron-mixed graphite, the oxidation was considerably suppressed by the boron content and the weight gain was observed due to the formation of B203 when the boron concentration exceeded 10%.
