Ultra-hard materials

Реферат: An ultra-hard material comprising at least three elements and having a Knoop hardness of at least 25 GPa and the formula: Rx Oy Nz having a crystallographic structure in which the average anion co-ordination number is 6 or more and wherein: R is an element selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium and tungsten, x is an integer from 1 to 3, y is an integer from 0 to 5, and z is an integer from 0 to 5, provided y and z cannot both be zero. Examples of such ultra-hard materials are TaON and TaZrO3N.