Abstract:
Disclosed is a process for preparing sintered polycrystalline CBN/ceramic conjoint masses in an HP/HT process which comprises subjecting a mixture of GBN and one or more of a ceramic material or metal which reacts with BN to form a ceramic material, to HP/HT conditions for inducing conversion of said GBN to CBN, inducing conversion of any of said metal to its corresponding metal ceramic, and forming said CBN/ceramic conjoint mass.
Abstract:
Single-crystal diamond consisting of isotopically pure carbon-12 or carbon-13 has been found to have a thermal conductivity higher than that of any substance previously known, typically at least 40% higher than that of naturally occurring IIA diamond. It may be prepared by a method comprising an initial step of low pressure chemical vapor deposition employing an isotopically pure hydrocarbon in combination with hydrogen, followed by comminution of the diamond thus obtained and conversion thereof to single-crystal diamond under high pressure conditions.
Abstract:
A composite element is disclosed, having improved heat conductivity, and is composed of a substrate whose surface layer enables homeo- or heteroepitactic growth of the diamond lattice from the gas phase, and of a low pressure diamond layer grown on the substrate, and in which the diamond layer grown is enriched compared to the normal diamond composition in the carbon isotope C.sup.12 and depleted in the heavier carbon isotopes C.sup.13 and C.sup.14.
Abstract:
The present invention concerns a method of producing a diamond thin film. A plasma-activated gas, obtained by exciting a starting material containing a carbon source gas, is brought into contact with a surface of a substrate, on which a diamond thin film is to be formed under the presence of an auxiliary member placed adjacent to a protruded portion present at the surface of the substrate. The diamond thin film is thereby formed on the substrate. An apparatus for producing a diamond thin film by means of a microwave plasma method has an auxiliary member placed adjacent to a protruded portion present at the surface of the substrate on which the diamond thin film is to be formed.
Abstract:
Broadly, the present invention is directed to a high pressure/high temperature (HP/HT) process for making polycrystalline CBN composite masses from graphitic boron nitride (GBN) in the substantial absence of catalytically-active material. The present invention specifically comprises subjecting a mixture of different structural forms of GBN to simultaneous conversion of each for making a CBN/CBN composite mass. Pyrolytic boron nitride/hexagonal boron nitride (PBN/HBN) mixtures are ideally suited for conversion into the inventive CBN/CBN composite masses of the present invention.
Abstract:
Abrasive particles and articles made from cubic boron nitride derived from coated hexagonal boron nitride which is substantially free of oxides and volatile contaminants. Polycrystalline CBN is prepared from HBN by removing oxide from the surface of HBN particles to form HBN particles having a substantially oxide-free surface. The HBN particles having a substantially oxide-free surface are coated with an agent which is capable of preventing re-oxidation of the surface of the HBN particles to form coated HBN particles in a substantially oxide-free state. The coated HBN particles in a substantially oxide-free state are then converted to a polycrystalline CBN by direct conversion of HBN to CBN. Coating agents include metals, metal carbides, metal nitrides and metal borides. A preferred coating agent is titanium carbide.
Abstract:
Superabrasive cutting elements, backed compacts and methods for their manufacture are disclosed wherein metal coated superabrasive particles are cemented under HPHT conditions. The superabrasives bond to the metal of the coating and the metal coatings of adjacent particles bond to each other forming a matrix. A binding aid with thermal expansion characteristics close to that of the superabrasive particle can be infiltrated through or otherwise mixed with the particles to assist in the bonding between the metal coatings and to fill in voids. Catalyst and non-catalyst binding aids can also be used. Uncoated, smaller superabrasive particles can be interstitially dispersed among the coated particles to increase the superabrasive concentration and can self bond to form a cemented/sintered structure. Tungsten is a preferred metal coating and silicon is a preferred binding/sintering aid. The superabrasive can be diamond, cubic boron nitride, boron doped diamond or crushed sintered polycrystalline aggregates. The free-standing cutting element can have a brazeable layer and the compact can be backed with, for example, cemented tungsten carbide. Free-standing cutting elements can be thermally stable up to 1,200.degree. C. Backed compacts can be thermally stable up to 1,100.degree. C.
Abstract:
A process for producing a diamond compact comprised of diamond crystals bonded mainly by silicon carbide. The diamond crystals are intimately mixed with silicon in the proportions 97 to 65 percent by weight of diamond to 3 to 35 percent by weight of silicon. The thus-mixed diamond crystals and silicon are placed immediately adjacent to one or more bodies of silicon within a container and subjected to high pressure and temperature so as to cause melting of the premixed silicon and of the external silicon which infiltrates into the interstitial spaces between the diamond crystals to cause most of the silicon between the diamond crystals to react with diamond to produce silicon carbide. The elevated temperature is in the range 1,100.degree. to 18,000.degree. C., and the elevated pressure is in the range 10 to 40 kilobars. The resulting compact contains between 50 and 85 volume percent of diamond with a density of at least 3.35 g/cm.sup.3 and a compressive strength of at least 10 kilobars.
Abstract:
Diamond compact composed of 60-95 volume % diamond crystals plastically deformed into a closely packed, rigid structure with contacts between the diamond crystals over extended mating surfaces arising from the plastic deformation. The diamond crystals are bonded together by an interstitial bonding material composed of a refractory carbide, such as silicon carbide, or a bonding material composed of a metal such as rhenium and a refractory carbide formed by reaction of a metallic bonding agent, such as tungsten, with carbon.
Abstract:
A plural number of types of material powders are accommodated in an accommodation chamber in a mixed state and the material powders are continuously subjected to a self-exothermic reaction inducing chemical reactions between the material powders caused by heat of reaction released when the mixed material powders synthesize. The synthesized material of high temperature due to the self-exothermic reaction is pressed by utilizing an electromagnetic force just after the finish of the self-exothermic reaction. The exothermic reaction is caused by an ignition circuit including an ignition electrode and the electromagnetic force is generated by an electromagnetic force generation circuit including an electric current inducing means. These circuits are connected through and regulated by a relay circuit. Thus the synthetic products of fine structure are obtained.