等方性高密度黒鉛の酸化消耗

Abstract

The weight loss of isotropic high-density graphite products as a result of oxidation was measured at different temperatures under a constant flow of dried air: at 550 °C for 24 h under an air flow of 4 L min-1, at 700 °C for 2.5 h under 4 L min-1, and at 1200 °C for 1 h under 2 L min-1. By observing the changes in the surface and cross-section of the specimen with oxidation, the weight loss is discussed in relation to the bulk density and whether a purification process was included during the graphite production. At 550 °C, oxidation even occurred inside the block and was markedly accelerated by the presence of metallic impurities, leaving small etch pits with a round cross-section. Weight loss on graphite products without a purification process was 10∼100 times larger than that on products after purification. The weight loss at 1200 °C could be related to the bulk density for all graphite samples, with or without purification.