Solid state reaction between tantalum (Ta) and tantalum carbide (TaC) powders during hiping

摘要

At high temperature and pressure, diffusion of carbon occurredbetween tantalum and tantalum carbide powders. Depending on the initial size ofthe tantalum grains, various ceramic grades were obtained by sintering Ta andTaC powders.Either an equilibrium composition was reached between the fine metal grainsand the tantalum carbide grains, leading to the formation of monolithic butunstoichiometric carbides. On the other hand, under the same experimentalconditions, ceramic-metal composites were prepared by using a coarse Ta grainspowder. In this last case, tantalum inclusions were dispersed inside the ceramicmatrix due to incomplete diffusion process and a carbon concentration gradientwas detected at the Ta-TaC interface.