väga suure kõvadusega keemiline ühend B4C, mida toodetakse booroksiidist (B2O3) süsinikuga taandamise teel elektriahjudes; kasutatakse abrasiivtöötlemisel, tehnokeraamika tootmiseks jms, very hard material (third only to diamond in hardness) B4C, produced by reduction of boric oxide (B2O3) by carbon in an electric arc furnace; employed as an abrasive in grinding wheels, belts, papers, powders, in articles of high resistance to abrasion etc
