ABSTRACT

This chapter describes the basic requirements of pressure, temperature and chemical environment for diamond synthesis. Before diamond synthesis was accomplished in the laboratory there were a few scientific hints regarding the conditions that would be favorable to diamond formation. The conditions of pressure and temperature required for diamond and cubic boron nitride synthesis are beyond the capability of ordinary commercial piston-and-cylinder type apparatus. Cubic boron nitride has proved to be an interesting and useful industrial abrasive material because of its combination of superhardness and chemical behavior. Because of the relative scarcity of diamond among the world's natural minerals, and because good diamond crystals are very highly valued as gems, diamond as a commodity has remained in short and capricious supply. The chapter considers the diamond-making processes in more detail, and presents some specific examples to illustrate the main points. Diamond is made on a small commercial scale by DuPont, using a shock compression process.