Abstract: The present invention relates to a diamond-carbon material, containing carbon, hydrogen, nitrogen, oxygen and incombustible impurities of a composition specified in the disclosure, and the surface contains methyl, carboxyl, lactone, aldehyde, ether and quinone groups.The material of the present invention is produced by detonating an oxygen-deficient explosive in a closed volume in a medium inert towards carbon, at a cooling rate of the detonation products of 200 to 6000 degree/min.

Abstract: In accordance with the present invention, there are provided methods for enhancing the color of minerals useful as gemstones. Invention methods are relatively inexpensive to carry out, avoid the use of hazardous materials, and require no specialized equipment.

Abstract: A diamond-containing material having the following element content ratio in per cent by weight: carbon 75-90, hydrogen 0.6-1.5, nitrogen 1.0-4.5, oxygen the balance, the following phase content ratio in per cent by weight: roentgen amorphous diamond-like phase 10-30, diamond of cubic modification the balance, and having a porous structure. 10-20% of the surface of the material consists of methyl, nitryl and hydroxyl groups of two types, as well as functional oxycarbonic groups of the general formula O.dbd.R where R represents .dbd.COH, .dbd.COOH, .dbd.CO, .dbd.C.sub.6 H.sub.4 O or any of their combinations, and 1-2% of the surface constits of carbon atoms with non-compensated links. A method for obtaining said material consists in detonation of a carbon-containing explosive substance with negative oxygen balance, or a mixture of explosive substances, in a closed volume in the atmosphere of gases inert to carbon, with an oxygen content of 0.1-6.

Abstract: Synthetic gemstones having extraordinary brilliance and hardness are formed from large single crystals of relatively low impurity, translucent silicon carbide of a single polytype that are grown in a furnace sublimation system. The crystals are cut into rough gemstones that are thereafter fashioned into finished gemstones. A wide range of colors and shades is available by selective doping of the crystal during growth. A colorless gemstone is produced by growing the crystal undoped in a system substantially free of unwanted impurity atoms.

Abstract: A solid state method of converting a polycrystalline ceramic body to a single crystal body includes the steps of doping the polycrystalline ceramic material with a conversion-enhancing dopant and then heating the polycrystalline body at a selected temperature for a selected time sufficient to convert the polycrystalline body to a single crystal. The selected temperature is less than the melting temperature of the polycrystalline material and greater than about one-half the melting temperature of the material. In the conversion of polycrystalline alumina to single crystal alumina (sapphire), examples of conversion-enhancing dopants include cations having a +3 valence, such as chromium, gallium, and titanium.

Abstract: Proposed is a grain boundary-free crystalline body of a perovskite structure having a chemical composition of the formula Pr.sub.1-x M.sub.x MnO.sub.3, in which M is calcium or strontium and the subscript x is a number of 0.3 to 0.5, which exhibits a magnetoresistance behavior with a phase transition between an insulator phase and a ferromagnetic metallic phase accompanied by the phenomenon of hysteresis. This grain boundary-free crystalline body can be obtained by subjecting a sintered body of a powder blend consisting of the oxides of praseodymium, manganese and calcium or strontium to a crystal growing treatment by the floating zone-melting method in an atmosphere of oxygen.

Abstract: A glass composition substantially comprising silicon oxide, calcium oxide and aluminum oxide, and its use for producing gems.

Abstract: Transparent, polycrystalline garnet bodies having desirable properties for use as laser material, luminescent x-ray scintillator materials and other uses are produced by mixing a chloride source solution of the desired cations with a basic ammonium solution to produce a precipitate having a substantially uniform composition which can be further processed to provide the desired transparent body. This precipitate is separated from the solution, dried, thermally decomposed at a temperature in the range from 700.degree. to 1,000.degree. C., pressed to form a compact, isostatically pressed at up to 60,000 psi to provide a green, unsintered compact having a density in the vicinity of 55% of theoretic density. That green compact is then sintered in oxygen at a temperature between 1,400.degree. and 1,700.degree. C. to produce the desired transparent body. Alternatively, the compact may be sintered in oxygen at temperatures in the range from about 1,400.degree. to about 1,600.degree. C.

Abstract: An artificial nucleus made of a crystallized glass is provided for use in the production of a pearl. The crystallized glass has been produced using a batch having the following composition:SiO.sub.2 . . . 40-65 wt. %MgO . . . 3-16 wt. %MgF.sub.2 . . . 6.5-17 wt. %K.sub.2 O . . . 7.5-18 wt. %ZrO.sub.2 . . . 0.01-15 wt. %CaO . . . 0.1-20 wt. %P.sub.2 O.sub.5 . . . 0.1-20 wt. %BaO and/or SrO . . . 0.1-13 wt. %and has crystalline phases composed primarily of tetrasilicon fluormica and formed in a glass matrix phase.

Abstract: A solid state process for the bulk conversion of a dense polycrystalline ceramic body to a single crystal body has been accomplished by heating the polycrystalline material to a temperature above one-half of the melting temperature of the material but below the melting point of the material. As the process is a solid state process, no melting of the ceramic body is necessary to convert it to a single crystal. The process has been used to convert a dense polycrystalline alumina body (PCA) containing less than 100 wppm of magnesia to sapphire (single crystal alumina) by heating the PCA to temperatures above 1100.degree. C. but below 2050.degree. C., the melting point of alumina.

Abstract: A CVD diamond die for drawing wire has top and bottom surfaces and opposing portions of a peripheral side located in respective regions of larger diamond smaller diamond grains. An opening which extends through the body from the top surface to the bottom surface is suitable positioned intermediate the side portions.

Abstract: Ceramic yttrium aluminate fibers are produced by processes that result in the formation of a microcrystalline ceramic oxide structure. In one process, a stoichiometric amount of a yttrium alkoxide is mixed with an aluminum alkoxide to produce a homogeneous mixture in an alcohol solvent. Following the addition of an alkoxide precursor of ZrO.sub.2 or of HfO.sub.2, the optional addition of an alkoxide precursor of MgO, and the subsequent addition of an organic acid, hydrolytic condensation to produce a suitable sol is accomplished by adding water. A slight excess of yttrium alkoxide can be used instead of the MgO precursor. The viscosity of the sol is adjusted to form a tractable gel that is spun into fibers which, after curing and firing, are shown to be microcrystalline in form, the resulting fibers having a submicron average grain size. Strength and stability result from the presence of solid particles of partially stabilized zirconia or hafnia at the grain boundaries and the triple points.

Abstract: A method for fabricating Y.sub.3 Al.sub.5 O.sub.12 (YAG) fibers from water soluble polymers includes a pre-YAG polymer synthesis, with solution viscosity adjustment followed by fiber spinning and heat treatment. The polymer synthesis employs polar solvents such as water or alcohol with a carboxylic acid containing at least two carboxyl groups.

Abstract: A method of growing mixed crystals having at least two lattice sites each having a different number of adjacent oxygen ions from melts of oxidic multi-component systems, homogeneous mixed crystals being grown such that the cations intended to occupy the first lattice site having the highest number of adjacent oxygen ions and to occupy the second lattice site having the next lowest number of adjacent oxygen ions are chosen such that the ratio of the bond length of the cations in the first lattice site to the bond length of the cations in the second lattice site is in the range from 0.7 to 1.5.

Abstract: A fluid jet orifice and method of making same. The fluid jet orifice comprises an orifice made of sapphire, the sapphire being annealed in a high temperature oxygen atmosphere. Preferably, the high temperature is in a range of approximately 1200.degree. C. to 1700.degree. C., the pressure of the oxygen atmosphere is atmospheric or above, and the annealing time is from approximately 4 to 40 hours.

Abstract: The bond strength between a diamond and the substrate onto which it is deposited by the chemical vaporization method is decreased to the point where the diamond can be removed from the substrate as a free standing monolithic sheet. The bond strength can be decreased by polishing the substrate, removing corners from the substrate, slow cooling of the substrate after deposition, an intermediate temperature delay in cooling or the application or formation of an intermediate layer between the diamond and the substrate. The free standing sheet of diamond can be used as a laser lens, metallized to form a mirror, or silver soldered to tungsten carbide to form a cutting tool.

Abstract: Ceramic bodies are bonded together via a layer of an oxidation reaction product of a molten metal, which metal is present in one or both of the ceramic bodies prior to bonding. At least one of the ceramic bodies comprises a ceramic product formed by the oxidation reaction of molten parent metal (e.g., alumina from molten aluminum) and grown as molten metal is transported through, and oxidized on the surface of, its own oxidation product. One or both of the ceramic bodies used in the bonding process contains surface-accessible channels of residual metal, i.e., metal channels which have resulted from molten-metal transport during the ceramic growth process. When the suitably assembled ceramic bodies are heated in the presence of an oxidant at a temperature above the melting point of the residual metal, molten metal at the surface of at least one of the ceramic bodies reacts with the oxidant to form a layer of oxidation reaction product, which may or may not incorporate at least one filler material.

Abstract: The invention relates to an optically effective material and a method for the manufacture thereof, having at least one element which can be arranged in and/or on a support, said at least one element being adapted to be arranged as desired in and/or on the support and being arranged optically in three-dimensionally effective manner. The element before adjustment of its position in and/or on the support is so varied that it assumes for itself an optically three-dimensional shape.

Abstract: A method of growing high purity diamond crystallite structures at relatively high growth rates on a temperature resistant substrate, comprising (a) flowing diamond producing feed gases at low pressure through a reaction chamber containing the substrate, the feed gases being comprised of hydrocarbon devoid of methyl group gases, i.e., acetylene or ethylene, diluted by hydrogen, and (b) while concurrently raising the temperature of the substrate to the temperature range of 600.degree.-1000.degree. C., thermally activating the feed gases by use of a hot filament located within the chamber and upstream and adjacent the substrate, the filament being heated to a temperature above 1900.degree. C., that is effective to generate a substantial atomic hydrogen (H) concentration and carbon containing free radicals. A substantial additional loss in carbon balance of the gases is triggered at a lower filament temperature indicative of the formation of intermediate substances that stimulate diamond growth.

Abstract: A process for producing structures from synthetic single-crystal pieces having identical major component and crystal systems by chemically bonding to produce integration and simulation. The process of the present invention makes structures of synthetic single-crystals that are placed together like non-crystals. Therefore, with the process of the present invention, new synthetic single-crystal structures of larger or smaller complicated precise shapes having applications in optical, chemical, and physical fields may be produced. The structures from synthetic single-crystal pieces are comprised of a plurality of colorless synthetic single-crystals or colored synthetic single-crystals having the same prime component and either no color or color impurities contained therein.

Abstract: A method of depositing a diamondlike carbon coating on a substrate. An ionized beam of pure methane or methane and hydrogen, and having an ion kinetic energy in the range of 500-1,000 eV is impinged on a substrate to deposit, thereon, a diamondlike carbon coating. Various substrates can be utilized, and various cleaning procedures are developed for use with the particular substrates to improve the adhesion of the diamondlike carbon coatings. The methane-hydrogen ratio and the operating pressure of the ionized gas can each be varied to vary the carbon-hydrogen ratio of the resulting diamondlike coating to thereby alter the characteristics of the coating.

Abstract: A process for forming a shaped article comprised of mullite whiskers comprising the following steps:a. preparing a mixture of aluminum fluoride and silicon dioxide in a weight ratio of about 7:3;b. firing the mixture in air at a temperature above about 750.degree. C. until complete conversion to topaz takes place;c. mixing the topaz product of step (b) with silicon dioxide in a weight ratio of about 18:1 together with a binder and firing at a temperature of above about 1400.degree. C. until complete conversion to mullite occurs.

Abstract: Vanadium garnet materials and a method for their preparation. The vanadium garnet material has a trivalent vanadium cation and a composition that falls within a specific prismatic-shaped volume in a quaternary composition diagram of MnO, CaO, V.sub.2 O.sub.3, and SiO.sub.2. In the process, specific amounts of separately pre-heated V.sub.2 O.sub.3, MnO, CaO and SiO.sub.2 powders are ground and mixed together, pelletized, heated at a temperature in the range of about 1100.degree. C. to 1400.degree. C. for 12 to 48 hours in an atmosphere of carefully selected oxygen pressure comprising a gas mixture of high purity CO.sub.2 and H.sub.2 to produce a liquid melt, and cooling, crystallizing out and separating said vanadium garnet material. A typical vanadium garnet material has the formula Mn.sub.1.3 Ca.sub.1.7 V.sub.2 Si.sub.3 O.sub.12. The vanadium garnet materials may be used in laser applications.

Abstract: There is disclosed a new and improved intraocular lens (IOL) for use by surgeons as a replacement for a person's cataractous lens. The disclosed lens is a synthetic sapphire lens having either a silicone or polyimide haptic thereby making the lens autoclavable. The lens is resistant to damage caused by YAG laser and eliminates the need for ridges of any kind on the surface of the lens which has previously been used to keep the lens off the posterior capsule of the crystalline lens. Eliminating the need for a ridge now allows the lens to be made much thinner and also eliminates the tiddlywink effect. The new IOL is approximately 1/3 to 1/5 the thickness of standard PMMA IOLs and is totally non-degradable.

Abstract: Shaped synthetic articles are fabricated by vapor deposition of synthetic diamond on releasable molds. A process is also provided for forming a shaped synthetic diamond article by coating a mold with an etchable layer and then depositing synthetic diamond on the etchable layer. The etchable layer is thereafter removed in an etchant bath, releasing the diamond article from the mold. The synthetic diamond articles are useful as high-temperature, corrosion resistant vessels and as wear surfaces.

Abstract: A chrysoberyl solid state laser comprising:(a) a rod-like laser medium composed of a chrysoberyl single crystal containing trivalent titanium ions as luminescent ions, the direction of c-axis of said crystal being made approximately the same as the longitudinal direction of the rod.(b) a means for generating excitation light for exciting said luminescent ions to emit light therefrom.(c) a means for focussing excitation light, generated by said means for generating excitation light, in said laser medium, and(d) a light resonator for generating oscillated laser light by resonating the light emitted from said luminescent ions with said focussed excitation light.

Abstract: Disclosed herein is a method of producing a single crystal of a high-pressure phase material having a pressure region of at least 1000 atm. in an equilibrium state at 25.degree. C. This method is characterized in that a plurality of single-crystalline plates (3, 16) of the high-pressure phase material, as a substrate on which growth is then caused. The plates are so formed that the crystal orientations thereof are substantially equal to each other. The plates are arranged so that single major surface (3a) thereof are substantially flush with each other and so that the crystal orientations thereof are substantially along the same direction to form the substrate (1). The growth takes place out of a vapor-phase whereby a single-crystalline layer (4) of the high-pressure phase material is formed on the substrate (2) by vapor-phase synthesis.

Abstract: Manufacturing process for a lead silicate based material habing a characteristic coloring ranging from orange-tinged yellow to blood red, having the following steps:a) preparing a bath or molten mass of lead silicate, produced by mixing lead oxide PbO and silica SiO.sub.2 in such proportions that the ratio between the two constituents is 65% by weight of lead oxide and 35% by weight of silica, whereby the temperature of fusion is chosen in the region of 1000.degree. and 1300.degree. C.;b) introducing into the fusion bath obtained during the foregoing state, copper oxide and a reducing agent, whereby the quantity of this addition is such that the concentration by weight of the copper oxide in the final product is in the region of 6 to 8%, the temperature of the fusion bath being maintained between 1000.degree. amd 1300.degree. C.;c) maintaining the fusion bath at rest always at the same temperature approximately between 1000.degree. C. and 1300.degree. C.

Abstract: A method is provided for making substantially transparent polycrystalline diamond film having a thickness greater than 50 microns which can be used in glazing applications and as a heat sink in microelectric applications. A mixture of hydrogen and methane is conveyed into a heated filament reacting zone which is adjacent to an appropriate substrate, such as a molybdenum substrate to produce non-adherent polycrystalline substantially transparent diamond film.

Abstract: Vanadium garnet materials and a method for their preparation. The vanadium garnet material has a trivalent vanadium cation and a composition that falls within a specific prismatic-shaped volume in a quaternary composition diagram of MnO, CaO, V.sub.2 O.sub.3, and SiO.sub.2. The prismatic-shaped volume represents compositions of liquids with which said vanadium garnet is in equilibrium on the liquidus surface and from which the vanadium garnet phase is crystallized. A typical vanadium garnet material has the formula Mn.sub.1.3 Ca.sub.1.7 V.sub.2 Si.sub.3 O.sub.12, as provided in the drawing by point F. The vanadium garnet materials may be used in laser applications.

Abstract: A process for producing unagglomerated single crystals of aluminum nitride having a size of at least 10 microns suitable for the reinforcement of metal and ceramic matrix composite materials. The process involves reacting alumina (or a precursor) with carbon under an atmosphere of nitrogen (or a precursor such as ammonia or an amine) at a temperature in the range of 1800.degree.-1950.degree. C. in the presence of an alkaki metal oxide (or precursor such as a carbonate) as a crystal growth promoter or catalyst. The alkali metal oxide is present in an amount required for the formation of crystals of the required size, preferably in the range of 10-60 microns. Particularly desirable crystals are produced if electrostatic precipitator dust is used as a source of the alumina, if petroleum coke or calcined anthracite coal is used as a source of the carbon and if the reaction is carried out in the presence of a porosity enhancer for the reaction mass, especially short cellulose fibres.

Abstract: A composite diamond grain which comprises a heat-resistant grain as a nucleus and discrete diamond crystal particles distributed on the surface of the grain or diamond crystal films formed to cover the entire surface of the grain and a method for producing the composite diamond grain by the vapor-phase process are disclosed. For the filament method which is one form of the vapor-phase method, tantalum is useful as the material for the filament. Since tantalum is susceptible of embrittlement by hydrogen, a treatment to be performed on tantalum for the elimination of this drawback is also disclosed.

Abstract: Crystalline diamond is grown on a substrate by placing the substrate on a nitride surface which completely covers a graphite support, creating an atmosphere of a gaseous carbon compound around the substrate, bringing the temperature of the nitride surface and the substrate to at least 600.degree. C., and subjecting the gaseous carbon compound to microwave energy suitable to cause the compound to decompose and produce carbon which deposits on the substrate and forms crystalline diamond thereon.

Abstract: A process is provided for forming synthetic diamond by vapor deposition of a carbon gas source in the presence of atomic hydrogen on a substrate contained in a fluidized bed. The diamond may be overcoated by vapor deposition of a non-diamond material.

Abstract: In a method of manufacturing a cubic boron nitride p-n junction body, cBN seed crystals (1) of a first conductivity type are made coexist with original BN (3) and a solvent (2) containing a doping material of a second conductivity type, to grow cBN of the second conductivity type from the seed crystals (1). The solvent (2) contains 0.1 to 5 percent by weight of the doping material. The seed crystals (1) are disposed one by one in a plurality of blocks of the solvent (2), which blocks are separated from each other, to be in contact with nothing but the solvent (2). Due to such disposal, no spontaneous nucleation is caused in portions other than the seed crystals (1). A large-grained cBN p-n junction body is obtained as the result.

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: A diamond film is grown on a substrate by providing a non-diamond substrate which has a face-centered cubic (fcc) crystal structure and small crystal lattice mismatch with the lattice of diamond, implanting carbon atoms into the crystal lattice of the substrate and causing the implanted carbon atoms to diffuse out of the substrate and grow epitaxially on the surface of the substrate. The preferred substrate is an fcc metal such as copper, nickel, fcc iron, fcc cobalt or fcc chromium.

Abstract: A hole-burning material which comprises at least one hole which is formed on a zero-phonone line and semi-permanently lasts without suffering from any change in the temperature range from 2 to 120 K. and which can be erased by irradiation of excited light having an energy larger than the zero-phonone line, in which the burnt holes have long life and deep depth and any single holes can be erased.

Abstract: Vanadium garnet material and a method for their preparation. The vanadium garnet material has a trivalent vanadium cation and a composition that falls within a specific polygon shaped area in a ternary composition diagram of V.sub.2 O.sub.3, CaO and SiO.sub.2. The polygon shaped area represents compositions of liquids with which said vanadium garnet is in equilibrium on the liquidus surface and from which the vanadium garnet phase is crystallized. A typical vanadium garnet material has the formula Ca.sub.3 V.sub.2 Si.sub.3 O.sub.12. The vanadium garnet materials may be used in laser applications.

Abstract: High pressure sintered bodies of polycrystalline diamond or carbide ceramics are rendered more resistant to cracking by establishing dispersed, localized "stress centers" of submicron size particles of lonsdaleite, diamond, or other form of metastable, high density carbon which has the capability of transforming crystallographically to graphite in situ in the body. When an incipient crack in the body approaches entrapped metastable particles along its path, the crack promotes or permits transformation of the metastable particles to graphite particles, with concomitant increase in their size, thereby resisting further propagation of the crack.

Abstract: Ceramic bodies are bonded together via a layer of an oxidation reaction product of a molten metal, which metal is present in one or both of the ceramic bodies prior to bonding. At least one of the ceramic bodies comprises a ceramic product formed by the oxidation reaction of molten parent metal (e.g., alumina from molten aluminum) and grown as molten metal is transported through, and oxidized on the surface of, its own oxidation product. One or both of the ceramic bodies used in the bonding process contains surface-accessible channels of residual metal, i.e., metal channels which have resulted from molten-metal transport during the ceramic growth process. When the suitably assembled ceramic bodies are heated in the presence of an oxidant at a temperature above the melting point of the residual metal, molten metal at the surface of at least one of the ceramic bodies reacts with the oxidant so to form a layer of oxidation reaction product which may or may not incorporate at least one filler material.

Abstract: A green diamond has a nitrogen content in its crystals within the range of 5.times.10.sup.16 to 3.times.10.sup.19 atoms/cm.sup.3, an absorption coefficient of H2 centers at a wavelength of 800 nm within the range of 0.3 to 6 cm.sup.-1, an absorption coefficient of the Ib type nitrogen at a wavelength of 500 nm within the range of 0.05 to 1.5 cm.sup.-1, and absorption coefficients of H3 centers, H4 centers, N-V centers and GR1 centers in the visible region of not more than 0.2 cm.sup.-1. Such green diamonds are produced by preparing a clear-yellow Ib type diamond having a nitrogen content in crystals within the range of 5.times.10.sup.16 to 3.times.10.sup.19 atoms/cm.sup.3, irradiating this diamond with an electron beam having not less than 1.times.10.sup.18 electrons/cm.sup.2 at an accelerating voltage of 2 to 4 MeV, and subjecting the diamond to a heat treatment at a temperature of 1500.degree. C.-1800.degree. C. in a vacuum of not more than 10.sup.-3 torr.

Abstract: A method of manufacturing a diamond laser crystal having an excellent laser efficiency is performed by first, preparing a synthetic type Ib diamond containing at least 60 volume percent of a (111) plane growth sector (43) is prepared. This synthetic diamond is then thermally treated under high temperature/high pressure, so that type Ib nitrogen contained in the synthetic diamond is converted to type IaA nitrogen. Thereafter an electron beam is applied to the synthetic diamond in order to generate vacancies in the synthetic diamond. Finally annealing is performed on the synthetic diamond to form H3 centers by coupling the type IaA nitrogen atoms contained in the synthetic diamond, with the vacancies. According to this method, the H3 centers can be formed in the synthetic type Ib diamond at high concentration, while formation of NV centers which become an obstacle to laser action, can be suppressed.

Abstract: A purple diamond has an absorption coefficient of the Ib type nitrogen at 500 nm, within the range of 0.2-2 cm.sup.-1, an absorption coefficient of the N-V center at an absorption peak of 570 nm, within the range of 0.3-10 cm.sup.-1, and absorption coefficients of the GR1 center, H2 center, H3 center, and H4 center which are less than 0.2 cm.sup.-1 in the visible region. A method of producing such a purple diamond uses as a starting material an Ib type artificial synthetic diamond crystal wherein the Ib type nitrogen content in the crystal is within the range of 8.times.10.sup.17 -1.4.times.10.sup.19 atoms/cm.sup.3, such a starting material is subjected to an electron beam irradiation of 5.times.10.sup.16 -2.times.10.sup.18 electrons/cm.sup.2 at 2-4 MeV, and then annealing the irradiated diamond in a vacuum of less than 10.sup.-2 Torr, at a temperature of 800.degree.-1100.degree. C. for more than 25 hours.

Abstract: A process in which (1) AlF.sub.3 and SiO.sub.2 or AlF.sub.3, SiO.sub.2, and Al.sub.2 O.sub.3 powders are formed into a green body of a desired shape and size; (2) the green body is heated at 700.degree. C. to 950.degree. C. in an anhydrous SiF.sub.4 atmosphere to form barlike topaz crystals; and then (3) heated in an anhydrous SiF.sub.4 atmosphere at about 1150.degree. C. to 1700.degree. C. to convert the barlike topaz crystals to needlelike single crystal mullite whiskers which form a porous, rigid felt structure. The felt has the same shape as the green body with about 1.5 or less percent change in linear dimensions. The felt can be used as preforms for ceramic-matrix or metal-matrix composites or by itself as thermal insulation.

Abstract: The present invention is directed to a method for synthesizing fluorine-containing, aluminosilicate crystals having a stoichiometry approximating that of topaz. The method comprises three basic steps:(1) vapors of a readily-oxidizable compound of silicon and of a readily-oxidizable compound of aluminum and fluorine are passed to a flame oxidation burner;(2) amorphous fluorine-containing, aluminosilicate particles resulting from the combustion of those gases are collected; and(3) the collected particles are sintered into an integral body at a temperature between about 650.degree.-925.degree. C.

Abstract: A method for vapor-phase synthesis of diamond comprises burning a raw material compound for synthesis of diamond thereby forming a combustion flame, disposing a substrate for deposition of diamond in said combustion flame, and keeping said substrate at a prescribed temperature, thereby inducing deposition of diamond on said substrate.

Abstract: A process for preparing mullite, 3Al.sub.2 O.sub.3.2SiO.sub.2, whiskers by(1) forming an intimate, anhydrous mixture of AlF.sub.3 and SiO.sub.2 powders in about a 12:13 molar ratio;(2) heating the mixture in an anhydrous, SiF.sub.4 atmosphere at about 700.degree. C. to about 950.degree. C. to form barlike crystalline topaz, Al.sub.2 (SiO.sub.4)F.sub.2 ; and(3) heating the barlike crystalline topaz under anhydrous conditions in a SiF.sub.4 atmosphere at a temperature of from about 1150.degree. C. to about 1400.degree. C. to produce mullite whiskers.The mullite whiskers produced can be used in ceramic and metal matrices without further chemical treatment.

Abstract: A process for preparing mullite whiskers by(1) forming an anhydrous, intimate, uniform mixture of AlF.sub.3, Al.sub.2 O.sub.3, and fused SiO.sub.2 powders in an amount selected to produce stoichiometric mullite or a solid solution of Al.sub.2 O.sub.3 in stoichiometric mullite;(2) heating the mixture in anhydrous SiF.sub.4 atmosphere at a temperature of from about 700.degree. to about 950.degree. C. to form barlike topaz crystals;(3) heating the barlike topaz in an anhydrous SiF.sub.4 atmosphere a a temperature of from about 1150.degree. C. to about 1700.degree. C. to produce the mullite whiskers.

Abstract: Composite articles, cutting tools and wear parts are prepared by densification of a mixture comprising whiskers, fibers, or particles of hard refractory transition metal carbides, nitrides or carbonitrides uniformly distributed in a titanium diboride matrix. Optionally, other dispersoids may also be incorporated. The preferred composite article or cutting tool has a fracture toughness equal to or greater than about 2.5 MN.multidot.m.sup.1/2. Methods of preparation and use are also disclosed.