Method and means for converting graphite into diamonds

Abstract

A host liquid, such as a liquid metal, which is "seeded" with small bubbles of an inert gas, is maintained in a sealed chamber at an ambient temperature of about 100° K. above the melting point of the host liquid, and at a static pressure ranging from 1 to 100 bars. A substance (for example carbon) which is capable of being allotropically transformed from a first form thereof (for example graphite) to a second form (for example diamond), is placed in the host liquid, which is then subjected to a time-varying acoustical pressure applied, for example, by a plurality of solid acoustical horns, which cause at least certain of the bubbles of inert gas to expand and then suddenly to collapse in a cavitation zone located substantially centrally of the chamber. By maintaining the host liquid at a pressure and temperature sufficient to cause the Hugonoit curve of the liquid to intersect a predetermined area of the phase diagram of the substance, the shock waves produced by the collapsing bubbles can be caused to envelop particles of graphite and to instantaneously transform them into diamond particles. The host liquid can be selected from a group consisting of aluminum, tin, gallium, thallium and indium, and alloys thereof; and the substance to be transformed may be selected from the group consisting of carbon, boron nitride and zinc sulphide.