Carbide

Vanadium carbide is manufactured by the carburization of pure vanadium pentoxide (mostly produced from ammonium vanadate) in vacuum at 1700°C. Vanadium carbide exhibits a high hardness, but its brittleness prevents its wide utilization in cemented carbides. In WC-Co alloys, it is added in quantities of < 1% by weight as a particle growth inhibitor.

carbide and Carbide

Niobium carbide, NbC, and tantalum carbide, TaC, are obtained by the reaction of their pentoxides with low ash carbon black at 1600 to 1800°C in a hydrogen atmosphere. A higher carbon content can be obtained by postcarburization at 1600°C.

Cheap niobium-containing tantalum carbide can be obtained from tantalum scrap, tantalum slag or ferrotantalum in an iron melt using the menstruum process.The carbide is separated chemically from the melt cake by dissolving the iron in warm hydrochloric acid.

Pure TaC is the only carbide utilized in cemented carbides in which it acts in a similar way to VC as a particle growth inhibitor. NbC-TaC mixed crystals are preferred for economic reasons and will replace TiC in cutting materials of the WC-TiC-Co-type and improve scaling resistance.