High-temperature oxidation of boron nitride

The oxidation resistance of boron nitride samples obtained by various methods and having different crystalline structures has been studied by thermogravimetric, differential thermal and IR spectral analyses. The real structure of a material being oxidized is of the greatest importance for the steady-state process of high-temperature oxidation. During the boron nitride oxidation, secondary processes are observed, associated with the rearrangement of the wurtzite-like BN lattice into a thermodynamically more stable hexagonal lattice of the graphite-like boron nitride. Nitrogen dioxide formation in the gas phase has been shown. Physico-chemical properties of the scale (B2O3 vaporization) impose limitations on the use of boron nitride-based materials in oxidizing media at temperatures higher than 1300°C.