Apparatus and methods for the manufacture of synthetic diamonds and cubic boron nitride

An apparatus for the manufacture of cubic Boron Nitride comprising:

• a pressure vessel having a chamber therein;
• and
• a body located in the chamber,
• wherein the pressure vessel and the body are formed of materials having different coefficients of expansion, the coefficient of expansion of the body being greater than the coefficient of expansion of the pressure vessel;
• wherein the chamber is configured to receive the body, and a Boron Nitride source;
• wherein the pressure vessel is formed from a material having a melting point in excess of 1327° C. and capable of reacting and withstanding forces generated by a pressure of at least 4.4 GPa located at the source of Boron Nitride in the apparatus, said pressure generated by differential thermal expansion of the body within the chamber when the pressure vessel is at temperatures in excess of 1327° C.;
• wherein the pressure vessel includes at least one housing member configured to resist said forces generated by differential thermal expansion of the body upon heating thereof;
• wherein the at least one housing member is formed from a material selected from the group consisting of:
• W;
• tungsten carbide;
• doped tungsten carbides;
• 3% Co doped tungsten carbide;
• boron carbide;
• carbon reinforced composites;
• carbon-fiber reinforced composites, carbon-fiber reinforced carbon composites, carbon reinforced graphite, carbon fiber reinforced graphite, and carbon-carbon;
• wherein the apparatus further comprises a furnace and the pressure vessel is situated in the furnace, said furnace configured to heat the pressure vessel, the body, and the Boron Nitride source to a temperature of at least 1327° C.;
• and
• wherein the coefficients of expansion of the body and the pressure vessel are selected such that upon heating thereof by said furnace to at least 1327° C. the pressure exerted on the Boron Nitride source is at least 4.4 GPa.