NEW DEVELOPMENT IN SUPERHARD COATINGS - THE SUPERHARD NANOCRYSTALLINE-AMORPHOUS COMPOSITES

The search for superhard materials considered so far mainly metastable solids, such as diamond, c-BN and C3N4 and single- and polycrystallin e superlattices. More recently, novel superhard nanocrystalline compos ites have been developed which appear superior to these materials in t erms of stability, resistance against oxidation and relatively simple preparation by means of plasma CVD. The present status of the theoreti cal concept for their design and the experimental results which suppor t it are briefly summarized. (C) 1998 Elsevier Science S.A.