Oxidation of boron carbide powder

Abstract

The oxidation of boron carbide powder was studied by using thermogravimetric technique. The oxidation was carried out by heating boron carbide powder in a stream of oxygen. Both isothermal and non-isothermal methods were used to study the kinetics of oxidation. Model-free isoconversional method was used to derive the kinetic parameters. A multistep (three steps) oxidation reaction was observed. The oxidation reaction did not reach to completion due to the formation of glassy layer of boric oxide on the surface of boron carbide powder. This acts as a barrier for further diffusion of oxygen into boron carbide particles and for the release of CO2 from boron carbide. The effective activation energy obtained using isoconversional method for boron carbide was 211 ± 8 kJ mol−1 for ‘α’ = 0.1–0.3. It was inferred that room temperature oxidation of boron carbide is a kinetically hindered process.