Oxidation of Boron at Temperatures between 400 and 1300°C in Air

Abstract

The oxidation behavior of powder compacts of both amorphous and crystalline boron was studied in air at temperatures between 400 and 1300°C. Crystalline and amorphous boron during the initial stage of oxidation followed a parabolic rate law. Crystalline boron formed a protective coating of boron oxide between 600 and 1100°C, and after 24 hours in this temperature range 16–19% of the boron was oxidized to B2O3. Amorphous boron oxidized at a greater rate than crystalline boron between 600 and 1000°C, and after 24 hours 22–26% of the boron was oxidized to B2O3. Above 1000°C vaporization of B2O3 took place, in addition to the formation of a brown suboxide of boron. The composition of this suboxide has been determined as B7O. Boron nitride was also formed during the oxidation of amorphous boron between 1100 and 1300°C.