Abstract: A synthetic diamond or cubic boron nitride particle is characterized by containing two or more stable isotopes of an element present in a ratio which is different to the ratio in which the isotopes exist in nature. The diamond or cubic boron nitride particle thus has a fingerprint. A preferred example of the element is nitrogen.

Abstract: A tool insert comprising an abrasive compact bonded to a cemented carbide support. The cutting edge of the tool is provided by the periphery of the compact. A plurality of recesses, each filled with abrasive compact material, extend into the cemented carbide support from the compact/carbide interface. The recesses are arranged in a series of rows, with each recess being staggered relative to its nearest neighbour in an adjacent row.In use, wear of the compact cutting edge occurs and eventually wears down to the carbide/compact interface. Thereafter, the carbide between adjacent recesses wears quicker than the diamond compact material which is located in each recess creating, in effect, a plurality of cutting ridges or projections.

Abstract: A cemented carbide which contains less than 20 weight percent of cubic boron nitride particle. The material is abrasive and wear resistant. The material is produced under cubic boron nitride synthesis conditions.

Abstract: A method of determining the nuclear radiation dosage to which a thermoluminescent crystal, such as a diamond or cubic boron nitride crystal, has previously been subjected, involves the steps of heating the cyrstal up while supporting it against gravity on an upwardly flowing stream of gas. The light which the crystal emits is collected and analyzed to give a radiation dosage measure in accordance with a know relationship between amount of collected light and radiation dosage. The gas stream may be a hot gas stream in which case the hot gas also serves to heat up the crystal. In one embodiment of the invention, the crystal is supported and heated up inside an integrating sphere which collects the emitted light.

Abstract: The invention provides a composite diamond abrasive compact comprising a thermally stable diamond compact directly bonded to a cemented carbide substrate. The thermally stable diamond compact comprises bonded diamond forming a coherent, skeletal mass and a second phase which preferably consists of silicon and/or silicon carbide. A method of producing the composite diamond abrasive compact under controlled elevated temperature and pressure conditions is also provided.

Abstract: In a method of removing second phase from an abrasive compact, the invention provides the improvement of forming a hole in the compact prior to or during the removal step. The compact is typically a diamond compact having a cobalt second phase. The preferred removal method is by leaching using as a leach medium hydrochloric acid in the presence of a platinum group metal catalyst.

Abstract: An abrasive body which comprises a cubic boron nitride compact bonded to a substrate. The compact has intergrowth between the cubic boron nitride particles which provides it with good thermal conductivity and has major surfaces on each of opposite sides, the one surface being bonded to the substrate and the other surface presenting a cutting edge. The substrate has a coefficient of thermal conductivity at least four times lower than that of the compact. The substrate is preferably made of aluminium oxide, Syalon or zirconia.

Abstract: A method of making inserts suitable for tool or drill bits which includes the step of fragmenting, e.g. by means of a laser beam, an abrasive compact in a plurality of discrete, non-segmental fragments. The inserts may have a variety of shapes, some of which are new, such as conical, truncated conical or truncated pyrimidal. The inserts are particularly useful for wire-drawing die blanks and core or oil-well drill bits.