Abstract: The disclosure is directed to polymeric B-aminoborazene compounds suitable for pyrolytic conversion to boron nitride. The B-aminoborazene compounds are preferably mixed with an organic solvent and a cross-linking agent to form a polymeric gel. The polymeric gel is then pyrolized to form boron nitride. The polymeric gel is useful to coat various forms and materials.

Abstract: Carbides, nitrides or carbonitrides of elements from the main groups III and IV and sub-groups III, IV, V and VI of the periodic system of elements are prepared by(i) reacting compounds of the formula MX.sub.m or R.sub.n MX.sub.m-n with a reactive hydrocarbon-containing compound or a mixture of compounds which is polymerizable and which contains a reactive compound with one C--OH-group in whichM is an element of the main group III or IV or sub-group of III, IV, V or VI of the periodic system of elements,X is a halogen,R is hydrogen or alkyl or aryl,m is an integer corresponding to the valency stage of M,n is an integer from 1 to one less than the velency stage of M, and(ii) thermally decomposing the resulting product from (i) to the corresponding carbide or to the corresponding nitrides or carbonitrides with further nitridation.

Abstract: Novel poly(alkenylpentaboranes) such as poly-2-vinylpentaborane are useful as precursors to BN or B.sub.4 C ceramics. The non-crosslinked poly(alkenylpentaboranes), which are soluble in common inert organic solvents, are prepared heat treatment of corresponding alkenylpentaboranes. The non-crosslinked poly(alkenylpentaboranes) are heated under an inert atmosphere to crosslink them, and the crosslinked products are pyrolyzed to yield B.sub.4 C. Alternatively, the non-crosslinked poly(alkenylpentaboranes) are heated in the presence of ammonia to yield a nitrogen-containing polymer which, upon pyrolysis, yields BN.

Abstract: A process for producing boron nitride comprises heating a mixture consisting of borohydride of alkali metal and ammonium chloride at a temperature range of from 800.degree. to 2200.degree. C. in a non-oxidizing atmosphere.

Abstract: The specification discloses a polycrystalline boron nitride of high purity and high density consisting essentially of rhombohedral crystals in which the three-fold rotation axes, parallel to the c-axis in the notation of hexagonal crystal system, of the crystals have a preferred orientation. The polycrystalline rhombohedral boron nitride can be obtained as bulk or thin film articles with desired shapes by chemical vapor deposition including the steps of introducing a source gas of boron and a source gas into a reactor containing a heated substrate and depositing boron nitride onto the heated substrate, wherein a diffusion layer of the source gas of nitrogen and/or the carrier gas is formed around the substrate. The polycrystalline rhombohedral boron nitride such obtained is very useful in applications such as crucibles for melting semiconductors, various jigs for high temperature services, high-frequency insulator, microwave transmission window and source material of boron for semiconductor.

Abstract: There is disclosed a novel process and apparatus for continuously producing very fine, ultrapure ceramic powders from ceramic precursor reactants in a self-sustaining reaction system in the form of a stabilized flame thereof to form ceramic particles and wherein the thus formed ceramic particles are collected in the absence of oxygen.

Abstract: A method is provided for producing large cubic boron nitride crystals having the size of 0.1 carat or larger.

Abstract: Admixing an aluminum alkyl, and optionally a boron compound, with a hydride of nitrogen in the gas phase and maintaining a gas phase temperature, optionally in the presence of a carrier gas, and producing aluminum nitride alone or in admixture with a precursor thereof or boron nitride or both.

Abstract: Boron-containing ceramics are formed from organoboron precermaic polymers which are carboralated acetylenic poolymers. The polymers can be formed by carboralating acetylenic or diacetylenic diols and condensing the diols to form carboralated polyesters. In an alternative process, polydiacetylene formed by the polymerization of diacetylene monomers having conjugated triple bonds are carboralated subsequent to polymerization. A process for obtaining readily soluble polydiacetylenes comprises heating a diacetylene diol in a high boiling solvent.

Abstract: A hexagonally crystalline boron nitride containing water-soluble boron containing impurities in such a magnitude that the amount of boron contained in an extract after boiling at 100.degree. C. in pure water is less than or equal to 100 .mu.g per gram of boron nitride. In order to purify the boron nitride, a purification process is carried out according to the steps of preparing fine particles of boron nitride powder; dispersing the boron nitride powder in a dispersion medium and stirred for a given period of time for removing water-soluble boron containing impurities; and drying the boron nitride in atmosphere, in which the vapor pressure is maintained lower than or equal to 10 mmHG and/or the process temperature is maintained lower than or equal to 100.degree. C.

Abstract: Metal carbide and metal nitride powders produced by the carbothermal reduction of one or more metal oxides reacted with a binder material and a carbonaceous additive or optionally, a binder capable of supplying carbon to the reaction. The metal oxides are selected from among SiO.sub.2, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, HfO.sub.2 and B.sub.2 O.sub.3 and are combined with the binder in the presence of carbon to form granules having a controlled pore volume. The granules are then subjected to a carbothermal reduction reaction, in the presence of a nitrogen or a neutral atmosphere, to produce metal nitrides or metal carbides respectively, having an excess of carbon incorporated therein. The product is subsequently heated to react the excess carbon within the compound with oxygen from the atmosphere to form carbon monoxide gas, which may be removed by an optional exhaust system.

Abstract: A process is disclosed for producing a solid material which, in some cases, may have a resultant purity of 99.999% or better which comprises contacting the solid material at a temperature approaching the melting point of the solid material with a purifying agent which is substantially nonreactive with the solid material to cause the impurities in the solid material to enter the material. After cooling, the purified solid material may be separated from the purifying agent and the impurities therein by leaching.

Abstract: A process for producing non-oxide compounds such as silicon nitride and silicon carbide by using a multi-stage apparatus constructed of a raw material drier section, a reactor section including a multiplicity of reaction vessels, and a non-oxidizing gas feeder section, is disclosed. The sections are arranged serially in the vertical direction. Raw materials are reacted with one another while fluidizing or bubbling by a hot non-oxidizing gas (argon or nitrogen) occurs in the raw material drier section and reaction vessels.

Abstract: A process for producing cubic boron nitride comprises heating at an elevated temperature and under high pressure a source of boron and a source of nitrogen in the presence of a fluoronitride or a source of fluoronitride.

Abstract: A process for making fine, uniform metal nitride powders that can be hot pressed or sintered. A metal salt is placed in a solvent with Melamine and warmed until a metal-Melamine compound forms. The solution is cooled and the metal-Melamine precipitate is calcined at a temperature below 700.degree. C. to form the metal nitrides and to avoid formation of the metal oxide.

Abstract: A method of synthesizing amorphous Group IIIA-Group VA compounds. A first solution is prepared which consists of a tris(trialkylsilyl) derivative of either a Group IIIA or Group VA element dissolved in an organic solvent. A second solution is then prepared which consists of a halide of the other of the Group IIIA or Group VA element dissolved in an organic solvent. Then the first and second solutions are mixed such that a Group IIIA-Group VA compound is formed along with a trialkylhalosilane by-product. The final step of the method consists of removing the trialkylhalosilane by-product and organic solvent mixture to form the Group IIIA-Group VA condensed phase.

Abstract: The powder of hexagonal boron nitride is prepared by heat-treating a powdery mixture composed of an oxygen-containing boron compound, e.g. boric acid, and a nitrogen compound, e.g. dicyandiamide and melamine, with admixture of minor amounts of a carbonaceous powder, e.g. carbon black, and/or borax. Further, an alkaline earth metal compound such as calcium carbonate is added either to the powdery mixture of the starting materials before the heat treatment or to the powder after the heat treatment. The h-BN powder has excellent sinterability so that sintered bodies of boron nitride having a high density and high bending strength can readily be prepared by use of a hot press.

Abstract: Metal carbide and metal nitride powders produced by the carbothermal reduction of one or more metal oxides reacted with a binder material and a carbonaceous additive or optionally, a binder capable of supplying carbon to the reaction. The metal oxides are selected from among SiO.sub.2, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, HfO.sub.2 and B.sub.2 O.sub.3 and are combined with the binder in the presence of carbon to form granules having a controlled pore volume. The granules are then subjected to a carbothermal reduction reaction, in the presence of a nitrogen or a neutral atmosphere, to produce metal nitrides or metal carbides respectively, having an excess of carbon incorporated therein. The product is subsequently heated to react the excess carbon within the compound with oxygen from the atmosphere to form carbon monoxide gas, which may be removed by an optional exhaust system.

Abstract: A sintered compact of cubic boron nitride is made by adsorbing and/or diffusing 0.005 to 1.000 percent by weight of water into a boron nitride compact containing alkaline earth metal boron nitride as a catalyst. The so prepared compact is then subjected to a treatment under high pressure at a relatively low temperature to form a dense cubic boron nitride sintered compact of high purity.

Abstract: A transparent BN-type ceramic material comprising 10 to 40 wt. % of boron (B), 35 to 55 wt. % of nitrogen (N) and 3 to 40 wt. % of silicon (Si) as the main component elements, and 1 to 10 wt. % of sub-component elements, with the property of not being crystallized by heat treatment at 1600.degree. C. for one hour, and a method of producing the above ceramic material by reacting a boron-containing compound, a nitrogen-containing compound and a silicon-containing compound at deposition temperatures in a range of more than 1300.degree. C. to less than 1700.degree. C. with the total gas pressure within a reaction furnace maintained in the range from 10 Torr to 100 Torr by use of a chemical vapor deposition method are disclosed.

Abstract: Method for making a ceramic mixture of boron and aluminum nitrides in the ratio of about 0.2 to 20 g atoms of aluminum per g atom of boron, and method for making shaped articles of the ceramic and of the intermediate from which the ceramic is prepared, comprising the steps (i) reacting a boron nitrogen compound with an organoaluminum compound in a suitable solvent to form a shapeable intermediate, and (ii) heating the intermediate at temperatures and under conditions to effect formation of the mixed nitrides.

Abstract: A process for producing boron nitride which comprises providing a nitrogen-containing nitride promoter, preferably melamine or dicyandiamide, in contact with an admixture of boron oxide and a sufficient amount of boric acid to enhance the formation of boron nitride under a non-oxidizing atmosphere, and maintaining same at sufficiently elevated temperature to form boron nitride.

Abstract: A process for preparing rhombohedral system boron nitride, which comprises mixing NaBH.sub.4 with at least an equimolar amount of NH.sub.4 Cl, and heating the resulting mixture in a non-oxidizing atmosphere at a temperature of at least 750.degree. C. and lower than 1000.degree. C. for at least 3 hours.

Abstract: A pyrolytic boron nitride article has a uniform structure 0.5 or less nodules/cm.sup.2 in average all through the overall surface of the article and 2 or less nodules in any portion of a unit square centimeter on the surface of the article. The pyrolytic boron nitride article is produced by depositing boron nitride through a vapor phase, using a boron halide gas and an ammonia gas as the starting materials. In production, the ammonia gas or a gas mixture containing the ammonia gas is not contacted directly with graphite at 300.degree. to 1850.degree. C.

Abstract: This invention relates to a tool for use in carrying out a cutting process, and more particularly to a cutting tool formed so that it can be sued to cut an iron material of a high hardness and thereby obtain a mirror-polished surface thereon, the cutting tool being characterized in that it is formed by attaching a monocrystal of boron nitride to the tip thereof so that predetermined surface and orientation of the crystal are set suitably. To be concrete, the present invention is directed to a cutting tool in which monocrystalline boron nitride is used for a tip which forms a blade of the cutting tool, (111) surface of this boron nitride being used as a relief surface of the blade, <211> direction being used as a cutting direction; or a cutting tool of the same material, in which (100) surface of the boron nitride is used as a relief surface of the blade, <110> direction being used as a cutting direction.

Abstract: The invention is a shaped article of boron nitride having a density of at least 95% of the theoretical density which consists of polycrystalline hexagonal boron nitride in the form of a homogeneous isotropic microstructure and which has been manufactured from pure boron nitride powder without the concomitant use of sintering aids by isostatic hot-pressing in a vacuum-tight casing at temperatures of from about 1200.degree. to 1500.degree. C. under a pressure of from about 50 to 300 MPa. Boron nitride powders having a free boric oxide content of not more than 1.0% by weight and having a specific surface area of from 5 to 30 m.sup.2 /g are used as starting material. The powders either are filled into prefabricated casings consisting of steel or glass and densified by vibration or are preshaped to form green bodies having pores open to the surface and then placed in prefabricated casings or coated with a material which forms a vacuum-tight casing.

Abstract: Disclosed is a method for preparing a sintered body containing cubic boron nitride which comprise the steps ofcontacting a starting material containing boron nitride and/or a starting material containing at least one selected from the group consisting of metals of groups IVa, Va and VIa of the periodic table, silicon, aluminum, iron group metals and compounds of the aforesaid metals with at least one selected from the group consisting of borazine, a borazine derivative and a compound composed of boron, nitrogen and hydrogen as will release hydrogen by a thermal decomposition under pressure to form boron nitride; andsintering the material under conditions of a predetermined pressure and temperature under which cubic boron nitride is kept stable. Also disclosed is a method for preparing cubic boron nitride which comprises, in addition to the above steps, recovering cubic boron nitride from the obtained sintered body by a chemical and/or physical manner.

Abstract: B-triamino-N-tris(trialkylsilyl)borazines, their condensation products, and the transformation of these into preceramic polymers amenable to fiber drawing and ultimately boron nitride fiber formation.

Abstract: Boron nitride containing titanium nitride in an amount of 0.05 to 10 wt. % which is produced at a relatively low temperature, utilizing a chemical vapor deposition technique. In the deposition process, boron, titanium and nitrogen source gases are introduced into an evacuated reactor together with a carrier and/or diluent gas and contacted with a heated substrate previously mounted in the reactor, whereby boron nitride with titanium nitride is deposited onto the substrate. The deposit thus obtained has a high density, a significantly improved heat-shielding ability, a high degree of anisotropy with respect to thermal diffusivity and a high chemical stability. By using such anisotropic boron nitride with BN ceramics, very useful BN type composite ceramics can be produced.

Abstract: A process for producing boron nitride is described, comprising reacting at least one boron compound selected from the group consisting of boric acid and metal salt thereof and at least one nitrogen-containing compound which is capable of bonding to the boron compound to form a compound in which a boron atom and a nitrogen atom co-exist, and then heating the compound thus formed at a temperature of at least 600.degree. C. in an atmosphere of inert or reducing gas. This process can produce high purity boron nitride at relatively low temperatures in high yields. Moreover, boron nitride can be obtained in desired crystal forms including a flake-like crystal form.

Abstract: A boron nitride complex comprising hBN in which lithium or an alkaline earth metal is diffused and supported in the form of its boron nitride. The boron nitride complex is prepared by heating hBN powder or a sintered product thereof and lithium, an alkaline earth metal, a lithium nitride or boride, or an alkaline earth metal nitride or boride in a non-oxidizing atmosphere to diffuse in and deposit on hBN powder or sintered product thereof, the lithium or alkaline earth metal in the form of its boron nitride. Also disclosed is a process for preparing a light-transmitting dense body of cubic system boron nitride, which comprises diffusing in and depositing on a sintered product of hexagonal system boron nitride, from 0.15 to 3.0 molar % of Me.sub.3 B.sub.2 N.sub.4 where Me is an alkaline earth metal, and sintering the Me.sub.3 B.sub.2 N.sub.4 -containing product thereby obtained, at a temperature of at least 1350.degree. C. under a thermodynamically stable pressure for cubic system boron nitride.

Abstract: Cubic boron nitride crystals are grown by subjecting reaction materials of low pressure phase boron nitride, a solvent material, and cubic boron nitride seeds to pressure and temperature conditions in the cubic boron nitride-stable region. The reaction materials are in the form of a pair of a superimposed solvent material plate and a low pressure phase boron nitride plate or a pile made of a plurality of the pairs of the superimposed solvent material plate and low pressure phase boron nitride plate, and a plurality of the seeds are disposed on either one or each of the confronting surfaces of the pair of the superimposed solvent material plate and low pressure phase boron nitride plate. Alternatively, the reaction materials are in the form of a plate made of a mixture of the solvent material and the low pressure phase boron nitride or a pile made of a plurality of the mixture plates, and a plurality of the seeds are disposed on a surface of each plate. The seeds have a particle size of not larger than 150 .

Abstract: A boron nitride type compound of the formula: LiMBN.sub.2 where M is calcium or barium and other similar compounds are provided. These compounds are prepared by heating a mixture of (i) finely divided Li.sub.3 N or metallic lithium, (ii) finely divided alkaline earth metal nitride selected from Ca.sub.3 N.sub.2, Mg.sub.3 N.sub.2, Sr.sub.3 N.sub.2, Ba.sub.3 N.sub.2 and Be.sub.3 N.sub.2, and/or an alkaline earth metal selected from Ca, Mg, Sr, Ba and Be, and (iii) hexagonal boron nitride at 800.degree. to 1,300.degree. C. in an inert gas or ammonia atmosphere thereby to react the ingredients (i), (ii) and (iii) with each other in a molten state, and then, cooling the reaction product to be solidified. The above-mentioned compounds are useful as a catalyst for use in the production of cubic boron nitride from hexagonal boron nitride.

Abstract: There are disclosed methods for preparing cubic boron nitride sintered body. One method involves pyrolyzing borazine and/or a borazine derivative to obtain a boron nitride; mixing said boron nitride and a catalyst composed of a metal and/or metallic compound; and reacting the mixture at a pressure of 3 GPa or more and at a temperature of 700.degree. C. or more. Another method comprises the step of pyrolyzing borazine and/or a borazine derivative to obtain a boron nitride; mixing said boron nitride and a catalyst composed of a metal and/or metallic compound; reacting the mixture at a pressure of 3 GPa or more and at a temperature of 700.degree. C. or more; and removing the catalyst from a formed product. The conversion rate into cubic boron nitride achieved with these methods is as high as 100%, and the obtained cubic boron nitride is highly pure and fine.

Abstract: Non laminating anisotropic boron nitride is prepared by reacting a boron halide with ammonia at a temperature of from 1100.degree. C. to 1600.degree. C. in the presence of a small amount of a volatile oxygen containing compound. The small amount of volatile oxygen containing compound is sufficient to prevent lamination yet small enough to prevent the finalized product from losing its anisotropy.

Abstract: The high pressure/high temperature catalyst sweep through process for making diamond and cubic boron nitride compacts has been improved by adding an intermediate metal or metal alloy. The added metal (whether alone or contained in an alloy) has a melting point below that of the catalyst (e.g. cobalt), is miscible with the catalyst, and preferably sweeps through the mass of abrasive crystals first. This modification has reduced flaw formation in such compacts.

Abstract: Semiconductor doping compositions comprising a suspension of (a) a dopant material, in the form of finely divided spherical particles of narrow size distribution from about 0.1 D to D, where D is the diameter of the largest particle and is no more than about (1.mu.) comprising a member selected from the group consisting of B.sub.x Si.sub.y, B.sub.x N.sub.y, P.sub.x Si.sub.y, P.sub.x N.sub.y, As.sub.x Si.sub.y and Sb.sub.x Si.sub.y wherein x and y vary from about 0.001 to about 99.999 mole percent, (b) an effective amount of a thermally degradable polymeric organic binder such as polymethyl methacrylate; and (c) an amount of an organic solvent, such a cyclohexanone, sufficient to dissolve said polymeric organic binder, such as polymethylmethacrylate, and to disperse said dopant material are disclosed.

Abstract: A method of producing diamond and/or diamond-like modifications of boron nitride from a material to be transformed, such material being carbon and/or boron nitride, with the use of explosive power, said explosive power being used by way of performing detonation of a charge comprising an explosive and a material to be transformed.

Abstract: A process for producing a sintered body of cubic system boron nitride comprises steps of:(a) mixing raw material boron nitride selected from the group consisting of hexagonal system boron nitride, cubic system boron nitride, and a mixture thereof with Me.sub.3 B.sub.2 N.sub.4 (where: Me represents an alkaline earth metal) in an amount of from 0.15 to 3.0 mol %; and(b) treating said mixed material at a temperature of 1350.degree. C. and above under a thermodynamically stabilized pressure condition of the cubic system boron nitride.

Abstract: Cubic system boron nitride from rhombohedral system boron nitride is produced by a shock wave compression method. The process comprises applying a thermodynamically stable pressure to rhombohedral system boron nitride to convert it to cubic system boron nitride.

Abstract: Rhombohedral system boron nitride is produced by heating a boron material selected from the group consisting of boron oxide, boric acid and an oxygen-containing boron compound capable of forming boron oxide when heated, at a temperature of from 1200.degree. to 2100.degree. C. to vaporize boron oxide and reacting the vaporized boron oxide with hydrogen cyanide or cyanogen gas.

Abstract: A process for preparing cubic boron nitride comprises heating hexagonal boron nitride and magnesium boron nitride at a temperature of at least 1350.degree. C. under a pressure at which the cubic boron nitride is thermodynamically stable, whereby the cubic boron having high strength and high purity can readily be obtainable. Also disclosed is a process for the preparation of magnesium boron useful as a starting material for the above process. This process comprises mixing hexagonal boron nitride and magnesium nitride or metal magnesium in a molar ratio of hexagonal boron nitride/magnesium being at least 0.6, and heating the mixture thus obtained, at a temperature of from 950.degree. to 1250.degree. C. under atmospheric pressure in a non-oxidizing atmosphere, e.g. a nitrogen atmosphere.

Abstract: A sponge-like free-standing pyrolytic boron article is made by reacting ammonia and gaseous boron halide diluted with an non-oxidizing gas to deposit pyrolitic boron nitride on a porous substrate such as open-pored vitreous carbon under a vacuum and then removing the substrate as by oxidation.

Abstract: Boron rich cubic boron nitride suitable for use in electroplating processes (e.g. nickel plating) has been made by an acid leaching process. Boron rich aggregated cubic boron nitride grinding grits are leached in a mixture of nitric and sulfuric acids, the following conditions being typical;(a) volume ratio of 67% nitric acid to 98% sulfuric acid of 10:20;(b) temperature of 250.degree. C; and(c) for a time of 1 hour.The process removes sufficient free surface boron to reduce the conductivity at the surface, resulting in an abrasive which does not overplate.FIG. 1 is a photomicrograph of a typical plated surface containing the improved CBN grinding grit of this invention, and FIG. 3 is an X-ray diffraction pattern characteristic of this new product.

Abstract: A process for producing polycrystals of cubic boron nitride which comprises exposure of hexagonal boron nitride to a pressure of from 40 to 70 kbar at a temperature of from 1,200.degree. to 1,800.degree. C. When the conversion of hexagonal boron nitride to cubic boron nitride reaches 20 to 65% by weight, the heating is switched off and pressure is increased to a value of from 80 to 120 kbar. Then the heating is resumed and temperature is elevated to 1,800.degree.-3,000.degree. C. Under these conditions the process is continued to full conversion of hexagonal boron nitride to cubic modification thereof.The process can be conducted in the presence of 0.5 to 10% by weight of a catalyst contributing to the conversion of hexagonal boron nitride into its cubic modification. The main portion of the catalyst is concentrated in the central portion of the volume of hexagonal boron nitride, the remainder - in the peripheral portion.

Abstract: A process is disclosed for producing a non-woven, boron nitride fiber mat, suitable for use as an electric cell separator in a lithium-sulfide battery. Molten boron oxide is centrifugally spun into strands and attenuated by an annular gas stream into fibers which are compacted at a controlled relative humidity into a mat. The mat of fibers passes through a needler, which repeatedly drives arrays of needles into the mat from either one or both sides, to reorient and intertwine the fibers, producing additional mechanical bonds thereamong. The needled mat then is heated in an anhydrous ammonia atmosphere to convert boron oxide in the fibers into boron nitride (BN). In an alternate embodiment the boron oxide fibers within the mat are converted into boron nitride before being passed through the needler.

Abstract: Disclosed is a method of producing cubic boron nitride, which comprises the steps of subjecting to a pressure of from 40 to 70 kilobars and to a temperature of from 1100.degree. to 2000.degree. C. a charge including hexagonal boron nitride and a conversion initiator selected from the group consisting of alkali and alkaline earth metals and borides of the foregoing metals, doping the charge with crystallohydrate in the form of a compound selected from the group consisting of sulfur-, halogen- or nitrogen-containing salts and their mixtures incorporating at least 5 molecules of crystallization water. According to another embodiment, the aforesaid charge is doped with a member selected from the group consisting of alkali metal hydroxide or alkaline earth metal hydroxide.

Abstract: Cubic boron nitride has been made from powdered hexagonal boron nitride by a process which comprises vacuum firing of the HBN and conversion by high pressure-high temperature processing at 55-80 kilobars and 1600.degree. C. to the reconversion temperature.The high pressure reaction cell has a special design which prevents the entrance of impurities into the sample. This cell, referring to FIG. 2, comprises, for example, a carbon tube (8) enclosing concentric titanium sleeve (9). Within the cylinder defined by the tube and sleeve are: the HBN sample (4), carbon filler (3), shielding tantalum foil discs (2) and carbon end plugs (10).The vacuum firing is done at pressures of 10.sup.-5 --10.sup.-10 mm Hg, 1400.degree.-1900.degree. C., for 5 minutes--4 hours, and is believed to form a thin, free-boron coating on the HBN particles.The process works on both pyrolytic (turbostratic) and graphitic hexagonal boron nitride.

Abstract: Fine metallic nitride powders having a high purity are prepared, without causing any plugging or other problems in the reaction apparatus and with easy heat control of the reaction, by reacting a metallic halide with liquid ammonia in the presence of an organic solvent which has a specific gravity higher than that of liquid ammonia, and also is not miscible or is only slightly miscible with liquid ammonia at a reaction temperature. The process according to the present invention is effected by introducing the metallic halide into the lower organic solvent layer of the reaction system.

Abstract: This a very simple process for making boron nitride by mixing sodium cyanide and boron phosphate and heating the mixture in an inert atmosphere until a reaction takes place. The product is a white powder of boron nitride that can be used in applications that require compounds that are stable at high temperatures and that exhibit high electrical resistance.