Ultra-hard materials: brief presentation and prospective research

During the last twenty years, the needs of the abrasives and cutting tools industry have led to an intensive research on ultra-hard materials (such as diamond). As a consequence, their exceptional mechanical characteristics were linked with their chemical compositions (based on light elements: B, C, N) and their crystal structures (tridimensionnality). These reports had led to new developments: mostly in theory on one hand, in the 80's and 90's, and, on the other hand, in synthesis, essentially since the beginning of this century. Then, the various remarks make us wonder about other questions induced by those materials: about chemistry (oxides), physical chemistry (new phases) and physics (polycrystalline materials).