Oxidation of Boron Carbide by Air, Water, and Air-Water Mixtures at Elevated Temperatures

A study of the oxidation of boron carbide powder has shown measurable reaction at temperatures as low as 250 °C with water vapor and 450 °C in dry air. Removal of the oxidation product by water vapor occurs at a rate in excess of the oxidation rate below 550°–600°C. The presence of on the surface was found to inhibit the oxidation by but not by air. Linear dependence of rate on the partial pressure of water was observed. The activation energy for the water‐ reaction was 11 kcal/mole‐°C, while that for the air‐ reaction was 45 kcal/mole. Oxidation by dry air occurs at a lower rate than with water vapor until approximately 700°C (for 235 mm water partial pressure).