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: Stable, viscous polymers of silicon, nitrogen and hydrogen are formed by reacting a halosilane with ammonia in the presence of a solvent comprising an aliphatic ether, a chloromethane or mixtures thereof. After the solvent has been removed from the reaction product, the polymer can be poured into a container of desired shape and then can be sintered to form a uniform silicon nitride product.

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: Compositions are disclosed for securing Si.sub.3 N.sub.4 parts together, these compositions being in the .beta.'-Y.sub.2 Si.sub.2 O.sub.7 --Y.sub.3 Al.sub.5 O.sub.12 tetrahedron, e.g. compositions in mole % comprising (1) 15% Si.sub.3 N.sub.4, 79.1% Y.sub.2 Si.sub.2 O.sub.7 and 6.9% Y.sub.3 Al.sub.5 O.sub.12 or (2) 25% Si.sub.2 AlON.sub.3 and 75% Y.sub.3 Al.sub.5 O.sub.12 Y. A method of securing Si.sub.3 N.sub.4 parts together comprises placing the composition between the parts to be bonded and heating to brazing temperature (about 1600.degree. C.) in nitrogen.

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 vapor growth method of forming deposition film on a plurality of substrates disposed within a cylindrical reaction vessel by causing flow of reaction gas under a reduced pressure through the reaction vessel, in which the treated surfaces of substrates are inclined to the upstream side of the reaction gas flow with respect to the axis of the reaction vessel and the individual substrates but the most upstream side one are each shifted in position with respect to the preceding one in a direction perpendicular to the axis of the reaction vessel.

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: Pre-polymers which are aminated methylpolysilanes are useful for the preparation of fine grained silicon carbide ceramic materials and silicon carbide-containing ceramics. The pre-polymers exhibit ease of handling and their use to obtain silicon carbide ceramic materials results in high yields.

Abstract: Novel, high yielding prepolymers are prepared by reducing chloropolysilanes with lithium aluminum hydride. These prepolymers exhibit good handling properties and are useful for preparing ceramics, silicon carbide ceramic materials and articles containing silicon carbide.

Abstract: Pre-polymers which are alkoxylated or phenoxylated methylpolysilanes are useful for the preparation of fine grained silicon carbide ceramic materials and silicon carbide-containing ceramics. The pre-polymers exhibit ease of handling and their use to obtain silicon carbide ceramic materials results in high yields.

Abstract: Pre-polymers which are alkylated or arylated methylpolysilanes are useful for the preparation of silicon carbide ceramic materials. The pre-polymers exhibit ease of handling and their use to obtain silicon carbide ceramic materials results in high yields.

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: Metal or ceramic powders having a narrow size distribution are produced by passing a gas entrained powder through an intense light beam which couples preferentially with the larger particles to heat and selectively vaporize a portion of the larger particles until their diameter approximates the desired size.

Abstract: Ceramic powder material mainly consists of silicon nitride wherein the content of oxygen combined with generally unavoidable impurities as measured by activation analysis accounts for less than 2% by weight. The above-mentioned ceramic powder material can also be prepared preferably by the method which comprises the step of heating raw ceramic powder material mainly consisting of silicon nitride to 1,400.degree. C. to 1,900.degree. C. in the presence of a separately prepared nonsintered molding of ceramic material or sintered molding of ceramic material having a porosity of at least 10%.

Abstract: A method of producing silicon nitride which comprises heating silica in a gas atmosphere comprising hydrocarbon gas, ammonia gas and hydrogen gas.

Abstract: A process for the direct thermal nitridation of silicon semiconductor devices in which the semiconductor body is placed in an atmosphere of N.sub.2, at a temperature of less than 1000.degree. C. The N.sub.2 is activated by an RF electrical field which ionizes the nitrogen, which then combines with the silicon surface.

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: A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 3,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C. with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with a second pipe for the silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than the distance from an opening end of the second pipe to the substrate.

Abstract: To provide for better distributor radio interference noise suppression and to localize resistance elements used in connection therewith as close to the spark gap of the distributor, the rotor electrode and/or the stationary electrodes in the distributor are made of a resistance material which has a sufficiently high resistance to provide for effective interference suppression; the material may be a high-melting oxynitride, particularly of a metal of the III or IV-B to VI-B groups of the periodic table; or a ceramic substrate, on which a coating is applied, for example of high melting point titanium, zirconium or aluminum oxide which are rendered conductive by being present in less than stoichiometric proportions; or silicon compounds such as chromium-silicon compounds, molybdenum-silicon compounds, with or without a matrix of silicon or ceramic-metal mixture in which the metal is both a binder and a conductive component, particularly Al.sub.2 O.sub.3 -Mo, Cr.sub.2 O.sub.3 -Si, SiC-Cr-Ni and B.sub.4 C.sub.

Abstract: High purity, fine Si.sub.3 N.sub.4 powder produced by the vapor phase reaction of SiCl.sub.4 with NH.sub.3 is amorphous. The crystallization rate of the amorphous powder is enhanced by heating the powder while in intimate contact with a titanium containing material, for example, TiN codeposited with the Si.sub.3 N.sub.4 by the simultaneous reaction of TiCl.sub.4 with NH.sub.3.

Abstract: This is a method of producing silicon nitride in a plasma arc furnace utilizing silicon metal or silicon dioxide as a starting material. When silicon metal is used it is reacted directly with a nitrogen bearing gas to produce silicon nitride. When silicon dioxide is used a two-step process is performed wherein the silicon dioxide is first reacted with hydrogen to produce silicon monoxide gas and water and thereafter the silicon monoxide gas is reacted with hydrogen and nitrogen to produce silicon nitride and water.

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: 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: 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: Composite ceramic articles formed by integrally assembling a plurality of previously molded constituent members without applying an adhesive to their joints and designed to have a density than higher 98% of the theoretical value, and a flexural strength greater than 50 kg/cm.sup.2 at 1200.degree. C., and a method of producing ceramic articles of particularly complicated shape which comprises the steps of previously molding a plurality of constituent members of complicated shape and later integrally assembling said constituent members without applying an adhesive to their joints.

Abstract: Method for the manufacture of ferrosilicon nitride is disclosed. The method produces ferrosilicon nitride with a silicon nitride content of 65% to 85% by weight by oxidizing the metallic iron which is present in the ferrosilicon nitride in an aqueous medium in the presence of selected oxidizing agents while forcing a mixture of air and steam through the aqueous medium.

Abstract: High purity, fine Si.sub.3 N.sub.4 powder produced by the vapor phase reaction of SiCl.sub.4 with NH.sub.3 is amorphous. The crystallization rate of the amorphous powder is enhanced by heating the powder while in intimate contact with a titanium containing material, for example, TiN codeposited with the Si.sub.3 N.sub.4 by the simultaneous reaction of TiCl.sub.4 with NH.sub.3.

Abstract: A method for forming a silicon nitride article is set forth. An article having silicon particles therein is formed in a manner which provides a degree of porosity for the article. The silicon particles of the article are reactable with nitrogen to form silicon nitride. The article is heated to a temperature below a significant reaction temperature at which nitrogen gas reacts with the silicon particles at a measurable rate. The article is surrounded with an atmosphere containing nitrogen gas. A reaction zone is established on at least a portion of the surface area of the article. The reaction zone has a temperature above the significant reaction temperature whereby the silicon particles in the reaction zone are reacted at a measurable rate with the nitrogen gas to form silicon nitride. The reaction zone is moved in a controlled manner from the surface of the article into the interior of the article whereby the article is progressively nitrided inwardly into its bulk from the surface thereof.

Abstract: A gas mixture of silane and ammonia is heated at temperatures between about 600.degree. C and 1000.degree. C producing an amorphous powdery reaction product which, when heated at a calcination temperature of at least 1100.degree. C yields ultrafine Si.sub.3 N.sub.4 powder of high purity.

Abstract: A process for preparing silicon nitride powder having a high .alpha.-phase content which comprises the steps of (a) providing a blended powder material composed of silica powder and amorphous carbon powder having an oil absorption of not less than 100 ml/100g, the weight ratio of the carbon powder to the silica powder being not less than 0.5, and then (b) nitriding and burning the blended powder material by heating in at a temperature of from 1300.degree. to 1700.degree. C while feeding a nitrogen-containing, non-oxidizing gas. The product obtained by this process is suitable as a raw material for the manufacture of high-density and high-strength sintered articles of silicon nitride.

Abstract: Silicon nitride bodies are improved by being impregnated with a silicon halide which is then converted to silicon imide in the pores of the body, which, in turn, is converted into silicon nitride.

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 temperature gas turbine engine components and the like, is prepared by heating a powdered mixture of silica, carbon and metallic silicon in a nitrogen containing atmosphere and then subjecting the material to a heat treatment in an oxidizing atmosphere for decarbonization of said material.

Abstract: Si.sub.3 N.sub.4 fibrous articles are produced by forming a low density compact of amorphous Si.sub.3 N.sub.4 powder and heat treating the compact to promote in-situ formation of fibrous crystalline alpha Si.sub.3 N.sub.4. Such articles are useful as thermal insulants, packing materials, resilient seals, etc.

Abstract: Si.sub.3 N.sub.4 ceramics exhibiting densities and modulus of rupture values heretofore obtainable only by hot pressing are produced by pressureless sintering of powder compacts of partly amorphours, partly crystalline Si.sub.3 N.sub.4 powder containing between 5 and 60 percent by weight of crystalline material.

Abstract: A polycrystalline silicon body is produced by forming a particulate mixture of silicon powder having an average particle size less than 3 microns and boron in an amount ranging from 0.1% to 5% by weight of the silicon powder, shaping the particulate mixture into a green body and sintering the body to a density of at least 60% of the theoretical density of silicon.

Abstract: An amorphous silicon nitride composition consisting essentially of from 95.0% to 99.9% by weight of amorphous silicon nitride and from 0.1% to 5.0% of carbon prepared by the vapor phase reaction of silicon tetrachloride, ammonia, and a gaseous hydrocarbon at temperatures from 1000.degree.C. to 1500.degree.C. This composition is particularly useful in the preparation of fully dense ceramics requiring high strength at elevated temperatures.

Abstract: Helical flow of hot plasma gas, e.g., hydrogen gas, produced by a gas vortex stabilized plasma arc is cancelled by introducing attenuating gas, e.g., hydrogen gas, into the hot plasma gas in a manner such that the attenuating gas assumes a vortical direction opposite to the helical flow of the hot plasma gas. The resulting gas stream is well-collimated. The well-collimated plasma gas stream is used in the preparation of finely-divided refractory metal and metalloid carbides, borides, nitrides, silicides and sulfides. Reactants for the preparation of the aforementioned refractory powders are introduced into the collimated plasma gas stream. The reaction is conducted in the gas phase within a reactor and solid, finely-divided refractory powder removed from the reactor.

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: The preparation of metal and metalloid carbides, borides, nitrides silicides and sulfides by reaction in the vapor phase of the corresponding vaporous metal halide, e.g., metal chloride, with a source of carbon, boron, nitrogen, silicon or sulfur respectively in a reactor is described. Reactants can be introduced into the reactor through a reactant inlet nozzle assembly. Inhibition and often substantial elimination of product growth on exposed surfaces of such assembly is accomplished by introducing the corresponding substantially anhydrous hydrogen halide, e.g., hydrogen chloride, into the principal reactant mixing zone.

Abstract: This invention is concerned with methods and materials for producing unitary silicon nitride structures by means of joining together at least two silicon based bodies with an intervening mixture of silicon powder and a heat removable liquid binder therefor between the joining faces, mantaining said faces in juxtaposition and slowly heating the assembly in a nitriding atmosphere to remove the liquid binder and to convert the material of said bodies and the intervening silicon powder into a unitary structure.

Abstract: A method is provided for preparing alpha silicon nitride powder in which very high purity, liquid silicon tetrachloride is reacted with an excess of ammonia gas in dry deoxygenated benzene or normal hexane at about 0.degree.C, yielding a precipitate of silicon diimide and ammonium chloride. After removal of the benzene or n-hexane from the precipitate, the mixture of silicon diimide and ammonium chloride powder is heated under a vacuum from room temperature to a temperature in the range of 1200.degree. to 1350.degree.C and maintained at the latter temperature for a period of about 2 to 8 hours. The product obtained is a high purity, submicron, alpha phase silicon nitride powder which is eminently suitable for the fabrication of dense, high strength, creep resistant and thermal shock resistant bodies for use in high performance gas turbine engines and in radome applications.

Abstract: A method is provided for making reactive metal silicide, particularly for use in adding lanthanum or other reactive metals to metal melts, by reacting reactive metal oxide with a metal silicide or silicon in an ESR furnace.

Abstract: A method of manufacturing a silicon nitride powder comprises heating a bed of silicon powder in a furnace having an atmosphere containing nitrogen so that the silicon reacts with the nitrogen to produce silicon nitride. The exothermic reaction between the silicon and the nitrogen is monitored, either by comparing the temperature in the reaction bed with the temperature at another point in the furnace, or by allowing the nitrogen containing atmosphere to flow through the furnace and measuring the rates of flow of the atmosphere into and out of the furnace. The partial pressure of the nitrogen in the furnace atmosphere is then controlled in accordance with the exothermic reaction so as to ensure that the temperature in the bed does not exceed a predetermined value above which .beta.-phase silicon nitride is formed, the partial pressure of the nitrogen in the furnace being controlled by effecting at least one of the steps of:A. diluting the nitrogen in the furnace atmosphere and,B. evacuating the furnace.