The oxidation of ZrB2, TaB2, NbB2, and W2B5 in atomic oxygen and by anodic polarization

The oxidation of ZrB2, TaB2, NbB2, and W2B5 in atomic oxygen and by anodic polarization was studied. All the investigated materials, both in the gas medium and in the electrolyte, were highly resistant to corrosion. The composition of the surface compounds was examined during the oxidation. High resistance to oxidation is explained by the B2O3 oxide. Oxidation of borides in both atomic oxygen and in 1N H2SO4 takes place at comparable rates, the corrosion resistance in the two media being similar.