A more general structural model which includes the induction time for gas-solid reactions-II. The kinetics of alpha-boron nitride oxidation

Experimental results are reported on the oxidation of alpha-boron nitride powders in the temperature range 1166–1321 K. The measurements were performed in a TGA, using small specimens. The experimental data were interpreted using the more general structural model, published previously. It is found that an induction time exists for the alpha-boron nitride oxidation, the gas-solid reaction occurs at the interface between the boric oxide and BN, and the oxygen must transfer through the boric oxide layer to the reaction interface. The relationships between induction time, reaction rate constant, effective diffusivity and temperature are also reported. The oxidation of flaky alpha-boron nitride powders can be described by the more general structural model.