… and borides, whether or not chemically defined, other than compounds which are also carbides of heading 28.49. …
Explanatory notes
… (2) Metal nitrides . Aluminium, titanium, zirconium, hafnium, vanadium, tantalum or niobium nitrides are obtained … with the following elements : oxygen ( heading 28.11 ), halogens ( heading 28.12 ), sulphur ( heading 28.13 ), … an explosive. (D) SILICIDES (1) Calcium silicide . Very hard, grey, crystalline masses. Used in metallurgy, for …