Oxidation behavior of amorphous boron carbide film deposited using the unbalanced magnetron sputtering method

The oxidation behavior of amorphous boron carbide thin film, deposited using the unbalanced magnetron sputtering method, was investigated. Weight change was measured using thermo gravity analysis under the condition of dry flowing air (100 mL/min), with increasing temperature of up to 1200 ℃ as well as at constant temperature. For the isothermal oxidation experiment, dry Ar gas was used until the oxidation temperature was stabilized; then, the Ar gas was replaced with dry air. The weight gain was negligibly small under 600 ℃ and then increased rapidly with increasing temperature. The isothermal oxidation curves show decreasing weight gain rate with oxidation time. At 1000 ℃, the weight gain was shown to become negative after a certain period. This isothermal weight change behavior can be ascribed to diffusional oxidation and weight loss due to the evaporation of liquid boron oxide. The possibility of the transition of boron oxide to boric acid at room temperature under an ambient atmosphere was also discussed.