In the field of metallurgy, boric oxide is used in the preparation of special welding and soldering fluxes, in chemical- bonded refractories, in the hardening of steel, and in the production of alloys with iron, nickel or manganese.
Boric oxide, the pure form of B2O3, is a hard glassy material, granular in texture. Exposed to the atmosphere it slowly absorbs water, reverting to boric acid.