ABRASIVE COMPACTS AND A METHOD OF MAKING THE SAME

摘要

1456765 Bonded abrasive compacts DE BEERS INDUSTRIAL DIAMOND DIVISION Ltd 8 Aug 1974 [10 Aug 1973 19 Oct 1973 29 March 1974] 34954/74 Heading C4V An abrasive compact comprises, as abrasive particles, cubic boron nitride, diamond or mixtures of these, bonded by a matrix comprising a refractory substance and a solvent capable of dissolving the abrasive particles at least to a limited extent. The solvent substance may also be capable of reacting with the refractory substance to form a hard material. The refractory substance may be a boride, nitride or silicide and a particularly preferred material isα-silicon nitride. Also suitable are magnesium oxide, spinel and alumina either alone or mixed with the nitride, silicide or boride. Several mixtures are listed. Suitable solvent substances are low melting metals or alloys such as aluminium, lead, tin, magnesium and lithium and alloys containing one or more of these. The abrasive particles are preferably present in a mixture in an amount at least 70% by volume and a ratio of the solvent substance to the refractory substance may be from 1 : 2 to 2 : 1. The various ingredients are preferably in finely powdered form preferably of average particle size less than 40 microns. To produce the compact the mixture of the ingredients is subjected to conditions of temperature and pressure at which the abrasive particles crystallographically stable and the solvent substance acts as a solvent. Pressures will normally be in the range 40 to 65 kilobars and temperatures in the range 1200‹ to 1300‹ C.