Abstract: A method is disclosed for producing silicon nitride wherein the crystal morphology is controlled. The method involves heating a mixture consisting essentially of a chlorosilane and ammonia at a sufficient temperature for a sufficient time to produce a nitogen containing silane as an intermediate. The bulk density of the intermediate is controlled to less than about 0.1 g/cc to result in the silicon nitride having a crystal morphology which is essentially all fibrous, or the bulk density can be controlled to greater than about 0.3 g/cc to result in the silicon nitride having a crystal morphology which is essentially all equiaxial, or the bulk density can be controlled to between about 0.1 g/cc and about 0.3 g/cc to result in the silicon nitride having a crystal morphology which is a mixture of fibrous and equiaxial. The intermediate is then heated at a sufficient temperature for a sufficient time in a non-oxidizing atmosphere to produce the controlled crystal morphology silicon nitride.

Abstract: Electronically excited nitrogen fluoride, NF*, is generated by dissociating fluoride azide, FN.sub.3. In a preferred embodiment, the FN.sub.3 is reacted with vibrationally excited molecules such as hydrogen halide, deuterium halide, carbon dioxide, or nitrogen. In second and third embodiments, the FN.sub.3 is dissociated by laser pumping or by detonation. The NF* can provide a short wavelength laser by pumping the NF(b-X) transition in a resonant chamber or by the addition of an emitting species such as BiF to convert the stored energy of the NF* to photons from the emitting species.

Abstract: This invention relates to a method for catalyzing the reactionsQZ+H.sub.2 X.fwdarw.QZX (1) psandQZX.fwdarw.QZ+H.sub.2 X (2)wherein Q=C or N;Z=O or S;X=O, S, NH or NR;R=C.sub.1 to C.sub.8 alkyl which may be linear, branched or cyclized,which comprises:contacting at least one polydentate nitrogen-containing chelating agent complexed with a metal atom with the reactants of one of said reactions, wherein said contacting takes place in the presence of a means for oxidizing when reaction (1) is catalyzed and in the presence of a means for reducing when reaction (2) is catalyzed.

Abstract: In the manufacture of silicon nitride powder by the vapor phase reaction of a silicon halide with ammonia at an elevated temperature in a flowing system, oxygen content of the silicon nitride is controlled by preventing entry of room air into the reaction means and by feeding wet nitrogen into the system at about the exit end of the reaction means.

Abstract: A method for producing .alpha.-form silicon nitride having a central particle diameter of 0.3 to 1.0 .mu.m (.alpha.-Si.sub.3 N.sub.4) of high-grade and fine powder for its sintered body excellent in heat-stability and mechanical strength which comprises heat-treating at 1,450.degree.-1,550.degree. C., in an atmosphere containing nitrogen, a mixture prepared by adding one of additives:(a) a mixture of at least one of Be, Sr, Ge, Sn, Ti, Hf and compounds thereof with 0.01-1 part by weight of silicon nitride powder having a BET specific surface area of 15 to 50 m.sup.2 /g and consisting substantially of the .alpha.-form crystal, and(b) a mixture of Zr and compounds thereof with 0-1 part by weight of silicon nitride powder having a BET specific surface area of 15 to 50 m.sup.2 /g and consisting substantially of the .alpha.-form crystal,in a total amount of 0.001-0.

Abstract: A high .alpha.-type silicon nitride powder is prepared by thermally decomposing a mixture of a crystalline silicon nitride powder having an oxygen content of at least 1.0% by weight and a nitrogen-containing silane compound.

Abstract: High purity silicon nitride particles are disclosed which are essentially alpha crystalline and which have a surface area of greater than about 25 m.sup.2 /g.

Abstract: Silicon nitride powder may be prepared by subjecting a composite comprising at least a monolayer of a carbonaceous pyropolymer possessing recurring units containing at least carbon and hydrogen atoms on the surface of a silica support to the action of nitrogen-containing atmospheres at nitriding conditions to form silicon nitride.

Abstract: A process is disclosed for producing high purity silicon nitride. The process involves contacting an organic compound which can be decomposed into silicon dioxide with essentially anhydrous ammonia at ambient temperature to form a two phase system consisting essentially of ammonia gas and the vapor of the organic compound and heating the two phase system at a sufficient temperature for a sufficient time to form the high purity silicon nitride.

Abstract: Nitrides and carbides are prepared by intercalating a monomer, a starting material of condensate, or a prepolymer into the interlamellar spaces or the vacant spaces of the crystalline structure of a natural mineral or an inorganic compound to prepare an intercalated compound and baking the intercalated polymer compound at a temperature in the range of 1100.degree.-1700.degree. C. under a nitrogen or reducing atmosphere. The present invention provides a method for readily preparing nitrides and carbides having the increased crystallinity at a low calcination temperature. Whiskers with larger diameters of 2 to 5 .mu.m can be prepared by adding carbon powder to the intercalated compound complex.

Abstract: A process is disclosed for producing high purity high surface area silicon nitride. The process involves contacting silicon tetrachloride with water to form a two phase system consisting essentially of a solid phase which is essentially silica gel and a liquid phase, heating the two phase system at a sufficient temperature for a sufficient time to partially dehydrate the silica gel followed by removing the solid phase from the liquid phase. A slurry is then formed of the solid phase in an aqueous solution of a water soluble organic carbon source. A dispersing agent is added to the slurry to disperse the silica gel, and the pH of the slurry is adjusted to greater than about 7, followed by heating the slurry at a sufficient temperature for a sufficient time to remove essentially all of the water and to decompose the carbon source.

Abstract: A process for the growth of silicon nitride whiskers consists of reacting a mixture of carbon and silicon dioxide powders at elevated temperature in a stream of nitrogen, said reaction mixture containing small amounts of metals such as chromium, magnesium, and nickel which promote the growth of silicon nitride whiskers by vapor phase transport. The whiskers obtained as a result of this invention are of much higher purity than those obtained by prior art.

Abstract: A method for producing a high-grade fine powder of .alpha.-form silicon nitride (.alpha.-Si.sub.3 N.sub.4) for use as sintered bodies excellent in heat-stability and mechanical strength which comprises heat-treating, in an atmosphere containing nitrogen, a mixture prepared by adding additive:a mixture of at least one of Mg, Ca, and compounds thereof with 0.01-1 part by weight of silicon nitride powder,in a total amount of 0.001-0.1 part by weight calculated in terms of elemental weight(s) of Mg or/and Ca, and 1 part or less by weight of silicon nitride powder, to 1 part by weight of silicon oxide powder and 0.4-4 parts by weight of carbon powder.

Abstract: In a method of manufacturing parts or powders made of a compound of silicon or of a metal by exothermally reacting parts or powders of silicon or a metal in the solid state with a gas, wherein the differential flow rate or the pressure variation of the reactive gas in contact with the part or the powder is sensed, and the reaction is performed at increasing temperatures as a function of the said differential flow rate or pressure of the reactive gas:the improvement wherein a maximum differential flow rate or a maximum speed of pressure drop of the reactive gas is predetermined as a function of the chemical nature of the parts or powders, and optionally as a function of the density and the size of the parts, and the rise in temperature is suspended when the differential flow rate or the speed of pressure drop of the reactive gas reaches the predetermined maximum value, beyond which the reaction would run away and prevent complete transformation of the parts or the powders being obtained.

Abstract: Crystalline poly(sulphur nitride) is deposited electrochemically at a bright platinum sheet cathode by electrolyzing solution of S.sub.5 N.sub.5 Cl in liquid SO.sub.2.

Abstract: A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of "whiskers" or needles is heated at temperature ranging from about 900.degree. C. to about 1200.degree. C. to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900.degree. C.

Abstract: NF.sub.3 is prepared with good yields by reaction between fluorine gas and an ammonium complex of a metal fluoride, such as (NH.sub.4).sub.3 AlF.sub.6, in solid phase. The metal flouride ammonium complex may be one additionally containing an alkali metal, such as (NH.sub.4).sub.2 NaAlF.sub.6. The gas-solid reaction is carried out preferably at temperatures above 80.degree. C. and at relatively low partial pressures of fluorine in the gas phase of the reaction system, so that the reaction is easy to control.

Abstract: Precursors, particularly of non-oxide ceramics, are prepared by special seeding, under carefully controlled conditions. Such procedures can lead to the preparation of unique powders, which may be useful, for example as abrasives, or further processed in special manner to prepare a variety of metal substances. Such procedures can permit final firing to sintered product.

Abstract: A method of manufacturing silicon nitride whiskers in which a carbon and silicon containing material having a thin configuration and sufficient porosity to permit both the passage of a gas therethrough and to provide spaces for growing whiskers therein is charged on a gas-permeable tray, and heated in a furnace of non-oxidizing atmosphere. The tray is moved intermittently through a series of temperature zones, increasing stage-by-stage from about 400.degree. C. to 1,300.degree. C., while a non-oxidizing gas is circulated through the porous material to remove any impurities. Thereafter, the heated tray is intermittently moved through a series of increasing temperature stages from about 1,350.degree. C. to 1,450.degree. C. in the presence of a flow of nitrogen gas to effect whisker growth. The heat-treated silicon nitride-containing material is dispersed in a two-phase mixture of a hydrophobic organic liquid and water. The desired silicon nitride whiskers can be isolated from the aqueous phase.

Abstract: Silicon nitride whiskers having a long fiber length in which .beta. type silicon nitride is well developed are produced by reacting a mixture of silica, carbon and cryolite in the specific molar ratio in a mixed gas atmosphere of N.sub.2 and NH.sub.3 by heating the mixture at a temperature of 1,250.degree.-1,450.degree. C. Kira of a ceramic industry waste may be used in place of silica and in this case N.sub.2 alone is used as a nitriding atmosphere.

Abstract: Refractory metal nitrides are synthesized during a self-propagating combustion process utilizing a solid source of nitrogren. For this purpose, a metal azide is employed, preferably NaN.sub.3. The azide is combusted with Mg or Ca, and a metal oxide is selected from Groups III-A, IV-A, III-B, IV-B, or a rare earth metal oxide. The mixture of azide, Ca or Mg and metal oxide is heated to the mixture's ignition temperature. At that temperature the mixture is ignited and undergoes self-sustaining combustion until the starter materials are exhausted, producing the metal nitride.

Abstract: Refractory metal nitrides are synthesized during a combustion process utilizing a solid source of nitrogen. For this purpose, a metal azide is employed. The azide is combusted with a transition metal of the IIIB, IVB group, or a rare earth metal, and ignited to produce the refractory material.

Abstract: .alpha.-Silicon nitride powder which is used as a raw material for the preparation of high strength silicon nitride with additives such as magnesia and yttrium oxide, and other sintered materials suitable for high temperatures gas turbine engine components and the like, is prepared by heating a powdered mixture of silica, carbon and at least one component selected from the group consisting of silicon nitride, silicon carbide and silicon oxynitride in a nitrogen containing atmosphere and then optionally subjecting the material to a heat treatment in an oxidizing atmosphere for decarbonization of said material as required.

Abstract: A process for synthesizing silicon nitride by reacting a silicon halide and ammonia at a high temperature, which is characterized in that at least while the reaction product is amorphous, hydrogen and chlorine are burned in the reaction zone where a halogen containing inorganic silicon compound and ammonia are reacting, and the reaction of said reactants is effected by the heat of combustion thus obtained.

Abstract: Silicon nitride of improved quality is obtained by using a liquid silicic acid or modified liquid silicic acid as a silicic substance and carbon in a powdered form, a precursor of carbon in a powdered form, or a precursor of carbon in the form of a solution as a carbonaceous substance, and thermally treating these raw materials in a non-oxidative atmosphere containing nitrogen. By this method, .alpha.-type silicon nitride can be easily obtained. Particularly, finely divided .alpha.-type silicon nitride suitable for use as the raw material for the production of high-strength sintered articles is also produced. .alpha.-type silicon nitride whiskers useful as a reinforcing material for ceramic and metallic articles is also obtained.

Abstract: A method of manufacturing highly purified silicon nitride including the steps of preparing a nitrogen-containing silane selected from the group consisting of tetra-amide-monosilane and silicon imide, and heat-treating the prepared nitrogen-containing silane in the presence of ammonia in an inner atmosphere at a temperature above 400.degree. C. for a period of at least two hours to obtain silicon nitride, and cooling and collecting the silicon nitride thus formed. The step of preparing the nitrogen-containing silane comprises continuously reacting gaseous silicon tetra-chloride with gaseous ammonia in an inner atmosphere at a temperature of from -30.degree. to 70.degree. C. to produce the nitrogen-containing silane as a product and collecting the product. The resultant silicon nitride so produced has a chlorine content of less than 0.05 weight percent and a nitrogen content of over 38 weight percent.

Abstract: A method for producing powder of a .alpha.-silicon nitride which comprises the steps of adding 0.1 to 2 parts by weight of carbon and 0.005 to 1 part by weight of at least one silicon compound selected from the group consisting of Si.sub.3 N.sub.4, SiC and Si.sub.2 ON.sub.2 to one part by weight, when converted to SiO.sub.2, of a liquid alkylchlorosilane that forms a precipitate and HCl by hydrolysis which precipitate is convertible to SiO.sub.2 at a baking temperature of 1300.degree. to 1550.degree. C., hydrolyzing the resultant mixture, washing the mixture to separate a solid component, and baking the solid component at a temperature of 1300.degree. to 1550.degree. C. in an atmosphere mainly consisting of a nitrogen gas or a gas of a nitrogen compound to effect formation of .alpha.-silicon nitride.

Abstract: A method for imparting ductility and very high electrical conductivity to very brittle refractory single crystals by subjecting said crystals to a hydrostatic deformation technique at room temperature and at pressures of from about 5 to 25 kilobars.

Abstract: High-purity .alpha.-type silicon nitride comprised of a granular crystal having an .alpha.-phase content of at least 95%, a nitrogen content of at least 38% by weight and an average particle size of not larger than 3 .mu.m is provided. This high-purity .alpha.-type silicon nitride is prepared by heating a nitrogen-containing silane compound at a temperature of at least about 1,300.degree. C. in a heating furnace comprised of a material containing a metal having a melting point exceeding 1,600.degree. C. and capable of being bonded with oxygen at the heating temperature.

Abstract: A method of manufacturing nitrided silicon parts by sintering a silicon powder containing aluminium under an atmosphere rich in nitrogen. A small quantity of carbon monoxide is added to the nitrogen atmosphere and the nitrogen and carbon monoxide partial pressures and the aluminium content of the silicon powder are chosen so that the oxidation reaction by the carbon monoxide on the nitrided silicon formed in the surfaces layers of the parts maintains therein an open porosity which is sufficient to allow the nitrogen to penetrate to the cores of the parts until the parts are homogeneously nitrided. Application to the manufacture of parts which must retain good mechanical strength at high temperature.

Abstract: Crystalline lithium nitride of increased conductivity having a hydrogen content of 0.2 to about 8 mole percent, a sodium, potassium and calcium content each of less than 10.sup.-2 weight percent and a silicon and iron content each between 10.sup.-2 to 10.sup.-3 weight percent, the metallic lithium from which said crystalline lithium was prepared having been of at least 99.9 weight percent purity.

Abstract: Novel fine grained pyrolytic silicon nitride is produced by adding a substantial amount of methane to the normal reactant gases. Silicon tetrafluoride and ammonia in ratios of 60:40 to 10:90 may be employed with additions of methane in amounts equal to from 50 to 500% of the sum of silicon tetrafluoride and ammonia. When these reactant gases are passed over a heated substrate at a low pressure pyrolytic silicon nitride with a grain size of less than about 10 microns results.

Abstract: A novel solid composition and method for generating fluorine and gaseous orine components comprising fluorine rich inorganic oxidizing salts such as tetrafluoro ammonium tetrafluoroborate borofluoride and a high energy fuel selected from the group consisting of metals and metal nitrides together with a complexing agent capable of reacting with and trapping the boron trifluoride combustion by-product.

Abstract: Compounds containing sulphur-nitrogen groups, such as S.sub.4 N.sub.4, S.sub.5 N.sub.5.sup.+ salts and poly(sulphur nitride), are made by reducing S.sub.4 N.sub.3 Cl or related compounds with anions (e.g. iodide) or metals (e.g. silver). Poly(sulphur nitride) may be made by passing S.sub.4 N.sub.3 Cl vapor or S.sub.5 N.sub.5 FeCl.sub.4 vapor through sulphidized silver wool and condensing the vapor.

Abstract: A method for producing powder of .alpha.-silicon nitride which comprises the steps of:adding 0.3 to 2 parts by weight of powder of carbon and 0.005 to 1 paret by weight of at least one silicon compound selected from the group consisting of Si.sub.3 N.sub.4, SiC and silicon oxide nitride series compounds to one part by weight (as converted to SiO.sub.2) to a liquid silane derivative which produces a precipitate and HCl by hydrolysis and further causes SiO.sub.2 to be grown by the baking of said precipitate, or the precipitate produced by hydrolysis of the liquid silane derivatives;hydrolyzing the resultant mixture, if necessary;washing the mixture to separate a solid component, if necessary; andbaking the solid component for reduction and nitrogenization at a temperature of 1300.degree. to 1500.degree. C. in an atmosphere mainly consisting of a nitrogen gas or a gas of a nitrogen compound.

Abstract: A method of manufacturing silicon nitride particles, either in an aglomerated or unaglomerated form, is disclosed. Basically, the particles to be nitrided are placed in an enclosed furnace and heated to a suitable temperature at which the enclosed furnace is filled with an initial gaseous mixture of nitrogen and hydrogen, the mixture containing not more than about 6% by volume hydrogen. Thereafter, the material is heated in the enclosed furnace to a temperature of about 900.degree. C. to about 1000.degree. C. at which time the nitrogen starts to react with the silicon in the furnace. Thereafter, the enclosed furnace is demand filled with a nitriding gas mixture consisting essentially of 1 to 10% by volume helium and about 99 to 90% by volume nitrogen. The furnace is heated to a suitable nitriding temperature and the demand filling of the chamber with the nitriding gas helium/nitrogen combination is continued until the nitriding operation is terminated.

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 invention relates to a process for purifying a nitrogen trifluoride containing atmosphere contaminated with dinitrogen difluoride. The atmosphere is purified by heating the nitrogen trifluoride atmosphere in the presence of a particulate metal capable of defluorinating dinitrogen difluoride, but inert to nitrogen trifluoride, preferably the metal being selected from the group consisting of iron, cobalt, and nickel, to a temperature of from about 300.degree.-1000.degree. F. for a time sufficient to effect defluorination of the dinitrogen difluoride.

Abstract: Low temperature photonitride (LTPN) films of excellent quality have been prepared at temperatures ranging from 300.degree. C. downward to 100.degree. C. by a photochemical vapor deposition process, wherein a mixture of silane, ammonia, and hydrazine is caused to react to form Si.sub.3 N.sub.4 films at the substrate interface. These films are suitable for the preparation of silicon nitride passivation layers on solid-state devices, such as metal-oxide semiconductors (MOS) and charge coupled devices to impart enhanced reliability.

Abstract: Porous reaction sintered silicon nitride body is infiltrated with an organosilicon compound after which the body is heated at a temperature sufficient to decompose the infiltrated material, resulting in a silicon nitride body having an increased density and significantly improved room temperature strength.

Abstract: Irradiation of collected S.sub.4 N.sub.4 decomposition products with light or radiation in the .gamma. to visible range enhances the initiation of polymerization of the decomposition products to produce polysulfur nitride, which is typically conductive and usually referred to as (SN).sub.x. Irradiation of a masked coating of collected S.sub.4 N.sub.4 decomposition products and completion of polymerization thereof and removal of non-irradiated, non-polymerized portions thereof will result in an electrically conductive coating disposed in a preselected pattern. S.sub.4 N.sub.4 decomposition products may also be dispersed in a matrix, e.g. a photographic emulsion which is transparent or partially transparent to light, or which may be rendered partially or selectively transparent or opaque. This might be useful, for example, for imaging applications, or for producing a selectively transparent pattern for subsequent photoinduced initiation of polymerization of the S.sub.4 N.sub.4 products.

Abstract: A plasma-arc process is disclosed for the production of powders of various chemical products, according to endothermic reactions, such as TiC and the like. The process consists essentially in carrying out, in a furnace with an anodic function without dissipative cooling, a series of steps comprising:(a) forming a chemically reactive fluidodynamic mass having a high thermal content and a high concentration of the desired reactive species, by injecting into the electronic column of a plasma-arc of a noble gas at least one reactant selected from the class consisting of metal and metalloid halides, the injection taking place, with mixing through a choker-injector-mixer nozzle which is electrically insulated;(b) causing the electronic condensation of said mass inside a main nozzle anode without dissipative cooling; and(c) injecting into said electronically condensed mass the residual part of said reactants necessary to the desired main chemical reaction for producing the chemical powder.

Abstract: This invention relates to an improvement in a process for purifying nitrogen trifluoride atmospheres generally contaminated with nitrous oxide, water, and dinitrogen difluoride. The improvement for extending adsorber life resides in reducing the dinitrogen difluoride content in the atmosphere to less than 0.03% by volume prior to passing the atmosphere through the adsorber.

Abstract: Electronic grade aluminum nitride semiconductor material may be uniformly nucleated and epitaxially formed on an aluminum oxide substrate by reacting aluminum oxide or aluminum nitride with nitrogen in the presence of carbon.

Abstract: Nitrogen trifluoride is prepared by passing elemental fluorine in intimate contact with liquid phase ammonium acid fluoride maintained at a temperature above its melting point but below about 400.degree. F for a time sufficient to effect reaction. Generally, ammonia is injected into the ammonium acid fluoride along with the fluorine to maintain a molar ratio of by-product hydrogen fluoride to ammonia of approximately 2.0 to 2.5.

Abstract: A process for the preparation of gaseous cyanogen chloride by a procedure involving reaction of hydrogen cyanide with chlorine in the presence of water with formation of hydrogen chloride as a by-product at a concentration of about 10 to 25% by weight and further involving converting by chlorination ammonium chloride, formed through acid-catalyzed hydrolysis of cyanogen chloride and admixed with the hydrogen chloride by-product, to nitrogen trichloride under pressure and at elevated temperature and decomposing the nitrogen trichloride to nitrogen and chlorine thermally or by U.V. radiation.

Abstract: Nitrogen trichloride normally explodes when heated to 95.degree. C. However, when a dilute solution of NCl.sub.3 in an inert solvent is heated to a temperature in the range of 105.degree.-140.degree., controlled decomposition to nitrogen and chlorine results. Nitrogen is innocuous and can be vented to the atmosphere. The chlorine is recovered. This method of NCl.sub.3 disposal is uncomplicated and non-polluting and constitutes a distinct improvement over prior art methods. The process of the invention finds utility primarily in destroying nitrogen trichloride formed as a by-product in the manufacture of trichloro isocyanuric acid.

Abstract: A process for making nitrogen trifluoride by introducing gaseous fluorine azide into a reaction zone containing a fluorinating agent selected from nitrosyl fluoride and chlorine trifluoride.

Abstract: A method of increasing the oxidation resistance of silicon nitride is disclosed. A furnace is preheated to a temperature in the range of 2500.degree.F to 2750.degree.F. The silicon nitride body to be treated is inserted into the preheated furnace. The silicon nitride article is maintained in the furance for a period of time sufficient to develop an oxidation resistant surface on the article. The period of time is generally in the range from one-half hour to five hours.

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.