Preparation of B4C-mixed graphite by pressureless sintering and its air oxidation behavior Original Research Article

B4C-mixed graphites with a boron concentration ranging from 3 to 32 mass% were prepared by pressureless sintering. For fabrications of these materials, a mixture of mesocarbon-microbeads and boron carbide powders was used. Final heat treatment temperature employed was around 2000 °C. The bulk densities of the materials were from 1.78 to 1.85 g/cm3, and the flexural strength was in the range of 44–87 MPa. These materials have a good machinability with shore hardness less than 71. Oxidation loss by air of this material with a total boron concentration more than approx. 10 mass% appeared to be almost completely suppressed at temperatures below 800 °C, where a little weight gain was observed due to the formation of boron oxide. In the temperature range from 900 to 1300 °C, appreciable oxidation loss was observed and the rate decreased as boron concentration increased.