Abstract: A tool insert comprises a substrate (10) having a support surface and a support ring extending laterally from the support surface. The support ring is sized to define a recess (14) within the confines thereof and a shelf about the periphery thereof. A layer (12) of ultra-hard abrasive material is located within the recess and bonded to the substrate and the support ring (16), and presents a primary cutting edge (22) for the tool insert. A protective layer (18) is bonded to the shelf about the support ring so as to protect the primary cutting edge. The protective layer provides a secondary cutting edge (20) for the tool insert, the depth of the protective layer being selected so as to be sufficient to protect the primary cutting edge whilst cutting, milling or drilling through a first substance but to expose the primary cutting edge upon encountering a second substance.

Abstract: A diamond electrode comprises a polycrystalline mass of diamond particles bonded together and has a porous surface, or an at least partly porous surface. The porous surface of the electrode is typically created by leaching non-diamond material, such as a second phase of a metallic material, at least in part, from the bonded polycrystalline mass of diamond particles, either before or after shaping it into an electrode. Alternatively, or additionally, the porous surface of the electrode may be created by subjecting a mass of diamond particles to conditions of elevated temperature and pressure to self-bond the particles together in the absence of a second phase.

Abstract: A composite material comprises a plurality of cores of material selected from the group comprising carbides, nitrides, carbonitrides, cemented carbides, cemented nitrides, cemented carbonitrides and mixtures thereof, dispersed in a matrix. The matrix comprises the components for making an ultra-hard material, such as diamond or cBN abrasive particles, and a suitable binder. The ultra-hard material is polycrystalline in nature and is typically PCD or PcBN. The cores are typically provided as individual particles or in the form of granules. The granules may be further coated with a second coating, which may be a similar material to that of the cores or of an ultra-hard material of a different grade to that of the first coating. The composite material typically takes on a honeycomb structure of a hard material and cores within the pores of the honeycomb structure bonded to the honeycomb structure. The pores of the honeycomb structure may be ordered or random.

Abstract: A cubic boron nitride cluster comprises a core (10) and an overgrown region, the overgrown region containing a plurality of cubic boron nitride crystallites (12) extending outwards from the core (10). The majority of the cubic boron nitride crystallites (12) have a cross-sectional area which increases as the distance from the core (10) increases. A method of producing cubic boron nitride clusters is also provided.

Abstract: An abrasive product which comprises a polycrystalline mass of self-bonded abrasive particles of irregular shape, the product being substantially free of a second phase and containing substantial plastic deformation of the abrasive particles. The abrasive particles are preferably diamond or cubic boron nitride and the plastic deformation of the particles is preferably at least 0.3 percent. The abrasive product may be made by subjecting a mass of the particles to elevated temperature and pressure conditions.

Abstract: The invention provides a mass of crystals, particularly diamond crystals, having a size of less than 100 microns and in which mass the majority of the crystals are faceted single crystals. The invention further provides a method of producing such a mass of crystals which utilizes crystal growth under elevated temperature and pressure conditions, the supersaturation driving force necessary for crystal growth being dependent, at least in part, on the difference in surface free energy between low Miller index surfaces and high Miller index surfaces of the crystals. Preferably, the method is carried out under conditions where the Wulff effect dominates.

Abstract: The invention provides a mass of crystals, particularly diamond crystals, having a size of less that 100 microns and in which mass the majority of the crystals are faceted single crystals. The invention further provides a method of producing such a mass of crystals which utilises crystal growth under elevated temperature and pressure conditions, the supersaturation driving force necessary for crystal growth being dependent, at least in part, on the difference in surface free energy between low Miller index surfaces and high Miller index surfaces of the crystal. Preferably, the method is carried out under conditions where the Wulff effect dominates.

Abstract: An abrasive product which comprises a polycrystalline mass of self-bonded abrasive particles of irregular shape, the product being substantially free of a second phase and containing substantial plastic deformation of the abrasive particles. The abrasive particles are preferably diamond or cubic boron nitride and the plastic deformation of the particles is preferably at least 0.3 percent. The abrasive product may be made by subjecting a mass of the particles to elevated temperature and pressure conditions.

Abstract: A diamond electrode comprises a polycrystalline mass of diamond particles bonded together and has a porous surface, or an at least partly porous surface. The porous surface of the electrode is typically created by leaching non-diamond material, such as a second phase of a metallic material, at least in part, from the bonded polycrystalline mass of diamond particles, either before or after shaping it into an electrode. Alternatively, or additionally, the porous surface of the electrode may be created by subjecting a mass of diamond particles to conditions of elevated temperature and pressure to self-bond the particles together in the absence of a second phase.

Abstract: A diamond cluster includes a core and an overgrown region containing a plurality of diamond crystallites extending outwards from the core, the majority of the crystallites having a cross-sectional area which increases as the distance of the crystallite from the core increases. Generally, at least 80% of the crystallites have a cross-sectional area which increases as the distance of the crystallite from the core increases. Furthermore, a method of producing a plurality of the diamond clusters includes the stops of providing a source of carbon, providing a plurality of growth center particles, each comprising a bonded mass of constituent particles, producing a reaction mass by bringing the carbon source and growth center particles into contact with a solvent/catalyst, subjecting the reaction mass to conditions of elevated temperature and pressure suitable for crystal growth, and recovering a plurality of diamond clusters from the reaction mass.

Abstract: A method of making a bonded, coherent material comprising a mass of crystals, preferably diamond crystals, in a matrix is provided. The steps include providing a source of the crystals of the type to be grown and which are substantially free of macroscopically faceted surfaces, producing a reaction mass by bringing the source crystals into contact with a suitable solvent/catalyst, subjecting the reaction mass to conditions of elevated temperature and pressure suitable for crystal growth in the reaction zone of a high temperature/high pressure apparatus to produce the material and removing the material from the reaction zone, the conditions of crystal growth being chosen such that the source crystals are converted to crystals having developed macroscopic facets of low Miller index. Preferably the conditions of elevated temperature and pressure used are such that the Wulff effect dominates.

Abstract: Diamond crystals may be grown by providing a source of diamond crystals, providing a plurality of growth centers defined by diamond crystals, mixing the source and growth center diamond crystals with a solvent/catalyst in particulate form to form a reaction mass, subjecting the reaction mass to conditions of elevated temperature and pressure suitable for crystal growth, and recovering the diamond crystals. The necessary supersaturation of carbon is achieved in the solvent/catalyst, at least in part, and preferably predominantly, by a selection of the particle size difference between the source crystal and the growth centers. The mass of diamond crystals produced by this method has a high concentration of twinned diamonds.

Abstract: A method of making a bonded, coherent material comprising a mass of diamond crystals in a matrix, which optionally contains another phase. The method includes the steps of providing a source of diamond crystals, providing a plurality of diamond centers defined by diamond crystals, producing a reaction mass by bringing the source and growth centers into contact with a solvent/catalyst, subjecting the reaction mass to conditions of elevated temperature and pressure suitable for crystal growth in the reaction zone of a high temperature/high pressure apparatus to produce the material, and removing the material from the reaction zone. The method is characterized by providing the necessary supersaturation of carbon in the solvent/catalyst, at least in part and preferably predominantly, by a selection of particle size difference between the source crystal and the growth centers. The mass of diamond crystals in the matrix of the bonded, coherent material of the invention has a high concentration of twinned diamonds.