Weight loss of isotropic high-density graphite during oxidation

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 24h under an air flow of 4Lmin−1, at 700°C for 2.5h under 4Lmin−1, and at 1200°C for 1h under 2Lmin−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. [TANSO 2015 (No. 268), 160–5.]