Abstract: A silicon nitride powder for sintering which, despite of its fine powdery form, shows a very small increase in the oxygen concentration with time and features excellent storage stability. The silicon nitride powder for sintering has a specific surface area of 5 to 30 m2/g, and is characterized by having a hydrophobicity (M value) of 30 or more and an increase in the oxygen concentration of 0.30% by mass or less after left to stand in the air of a humidity of 90% and 20° C. for 48 hours. The silicon nitride powder for sintering can be obtained by dry-pulverizing aggregated masses of the silicon nitride in an inert atmosphere in the presence of a silane coupling agent.

Abstract: The present invention relates to a method for producing a metal nitride, which is a method for synthesizing a metal nitride by igniting a raw material powder containing a metal powder housed in a reaction vessel (2) under a nitrogen atmosphere and propagating nitriding combustion heat of the metal powder to the whole of the housed raw material powder, characterized in that the raw material powder is housed in the reaction vessel (2) as a molded body (1B) having a void ratio of 40 to 70%. According to the present invention, it is possible to provide a method for producing a metal nitride capable of suppressing the occurrence of powder scattering and improving the recovery rate of the metal nitride.

Abstract: The present invention relates to a method for producing a metal nitride by igniting a raw material powder containing a metal powder filled in a reaction vessel under a nitrogen atmosphere and propagating nitriding combustion heat generated by a nitriding reaction of the metal to the whole raw material powder, the method including forming a heat insulating layer made of a material having nitrogen permeability and inert to the nitriding reaction on an upper surface of a layer made of the raw material powder. According to the present invention, it is possible to provide a method for reducing the amount of unreacted metal powder when producing a metal nitride by a combustion synthesis method.

Abstract: The present invention is directed to a method for producing a silicon nitride sintered material, the method including heating a molded article, which contains a silicon nitride powder having a ? phase ratio of 80% or more, a dissolved oxygen content of 0.2% by mass or less, and a specific surface area of 5 to 20 m2/g, and a sintering auxiliary containing a compound having no oxygen bond, and which has an overall oxygen content controlled to be 1 to 15% by mass and an aluminum element overall content controlled to be 800 ppm or less, to a temperature of 1,200 to 1,800° C. in an inert gas atmosphere under a pressure of 0 MPa·G or more and less than 0.1 MPa·G to sinter the silicon nitride.

Abstract: A process for producing a silicon nitride powder characterized by comprising a step of providing a starting material powder containing not less than 90% by mass of a silicon powder; the step of filling a heat-resistant reaction vessel with the starting material powder; a step of obtaining a massive product thereof by a combustion synthesis reaction by igniting the starting material powder filled in the reaction vessel in a nitrogen atmosphere and permitting a heat of nitriding combustion of silicon to propagate to the whole starting material powder; and a step of mechanically milling the massive product by a dry method.

Abstract: A process for producing polycrystalline silicon, comprising: a silicon deposition step for producing silicon through a reaction between a chlorosilane compound and hydrogen; a conversion reaction step for removing hydrogen chloride contained in an exhaust gas discharged from the silicon deposition step by bringing the exhaust gas into contact with activated carbon; a separation step for separating hydrogen contained in the gas after the conversion reaction obtained from the conversion reaction step; and a recycling step for supplying hydrogen obtained from the separation step to the silicon deposition step, wherein at least one of the following conditions (1) and (2) is satisfied: (1) the gas after the conversion reaction obtained from the conversion reaction step is brought into contact with an adsorbent containing a Lewis acid compound before the separation step; and (2) hydrogen obtained from the separation step is brought into contact with an adsorbent containing a Lewis acid compound before it is supplie

Abstract: A method for producing polysilicon includes a deposition step for depositing polysilicon from raw material gas including chlorosilanes, and a heat recovery step of supplying exhaust gas generated from the deposition step in a boiler type heat recovery device provided with an exhaust gas pipe and then recovering heat. A gas temperature at an exhaust gas pipe outlet of the boiler type heat recovery device is set to 200° C. or more, and an exhaust gas flow rate at the exhaust gas pipe outlet in the boiler type heat recovery device is adjusted to 10 m/second or higher.

Abstract: There is provided a silicon production method which comprises producing semiconductor grade silicon while producing solar grade silicon by converting a portion of trichlorosilane into silicon for solar cells. There is also provided an industrially advantageous method that removes contaminants from a chlorosilane circulating system which produces trichlorosilane in producing silicon from trichlorosilane by a vapor deposition method.

Abstract: A structure for mounting a novel reaction tube is capable of following up the thermal expansion of the reaction tube without the need of hanging down the reaction tube in the apparatus for producing silicon. In a reaction unit in a reaction vessel body of the apparatus for producing silicon, there are provided a gas feed pipe for feeding chlorosilanes and hydrogen, a reaction tube for precipitating silicon, a high-frequency coil arranged on the outer circumferential side of the reaction tube to melt the precipitated silicon, a heat insulating material provided between the reaction tube and the high-frequency coil, and an intermediate wall provided at the lower portion of the reaction unit to support the heat insulating material. The reaction tube is supported on the upper surface of the intermediate wall.

Abstract: A cylindrical vessel made of carbon is used in the production of silicon. The inner surface of the vessel comes into contact with a silicon melt, wherein the permeation with silicon melt is reduced, formation of SiC is suppressed, and the vessel is resistant to deformation even when volumetric expansion ascribable to silicon is brought about. The carbon-made cylindrical vessel is made of a carbon material having a bulk specific gravity of 1.8 or more. The thermal expansion coefficient of the carbon material at 350 to 450° C. is preferably 3.5×10?6/° C. to 6.0×10?6/° C. A process for producing silicon uses said vessel wherein a chlorosilane is reacted with hydrogen.

Abstract: A process for producing silicon comprises the steps of a reduction step [1] of depositing silicon by reacting chlorosilanes and hydrogen in a reactor under heat and discharging an exhaust gas that contains hydrogen, oligomers of silanes, and a silicon powder; a carring step [2] of carrying the exhaust gas that has been exhausted in the step [1] while keeping a temperature of the exhaust gas at not less than 105° C.; a removal step [3] of supplying the exhaust gas that has been carried in the step [2] to a filter at a temperature of not less than 105° C. and discharging the exhaust gas from the filter at a temperature of not less than 105° C. to remove the silicon powder from the exhaust gas and give a mixed gas that contains the hydrogen and the oligomers of silanes; and a separation step [4] of cooling the mixed gas that has been obtained in the step [3] to separate the hydrogen as a gas phase from the mixed gas.

Abstract: To provide a structure for mounting a novel reaction tube, which is capable of following up the thermal expansion of the reaction tube without the need of hanging down the reaction tube in the apparatus for producing silicon. In a reaction unit 3 in a reaction vessel body 2 of the apparatus 1 for producing silicon, there are provided a gas feed pipe 6 for feeding chlorosilanes and hydrogen, a reaction tube 7 for precipitating silicon, a high-frequency coil 11 arranged on the outer circumferential side of the reaction tube 7 to melt the precipitated silicon, a heat insulating material 9 provided between the reaction tube 7 and the high-frequency coil 11, and an intermediate wall 8 provided at the lower portion of the reaction unit 3 to support the heat insulating material 9. The reaction tube 7 is supported on the upper surface of the intermediate wall 8.

Abstract: A process for producing silicon comprises the steps of a reduction step [1] of depositing silicon by reacting chlorosilanes and hydrogen in a reactor under heat and discharging an exhaust gas that contains hydrogen, oligomers of silanes, and a silicon powder; a carring step [2] of carrying the exhaust gas that has been exhausted in the step [1] while keeping a temperature of the exhaust gas at not less than 105° C.; a removal step [3] of supplying the exhaust gas that has been carried in the step [2] to a filter at a temperature of not less than 105° C. and discharging the exhaust gas from the filter at a temperature of not less than 105° C. to remove the silicon powder from the exhaust gas and give a mixed gas that contains the hydrogen and the oligomers of silanes; and a separation step [4] of cooling the mixed gas that has been obtained in the step [3] to separate the hydrogen as a gas phase from the mixed gas.

Abstract: A solidified mass for a high-purity multicrystal silicon material that is preferably applicable to producing crystal type silicon ingots for photo voltaics, and a process for producing the solidified mass are provided. The mass of silicon solidified from molten state is a solidified mass produced by dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, said solidified mass containing bubbles and having (i) an apparent density of not less than 1.5 g/cm3 and not more than 2.2 g/cm3 and (ii) a compressive strength of not less than 5 MPa and not more than 50 MPa. The process for producing a mass of silicon solidified from molten state includes the steps of dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, wherein the surface temperature of the vessel for receiving the molten silicon is not lower than 0° C. and not higher than 1000° C.

Abstract: In a reaction apparatus of the chlorosilanes for heating a reaction portion that is a section from the bottom end portion to a specified height in the carbon reaction vessel and that has an inside face to which silicon has deposited, and for reacting the chlorosilanes by making the chlorosilanes and hydrogen to come into contact with the inside face of the reaction portion, a gas penetration preventing processing for preventing the chlorosilanes supplied to the reaction vessel from penetrating a pipe wall of the non reaction portion in the reaction vessel is carried out to the inside face and/or the outside face of the non reaction portion on the side upper than the reaction portion in the reaction vessel.

Abstract: There is provided a reaction vessel whereby silicon produced can be smoothly recovered dropwise without excessive thermal load on constitutional parts of the reaction vessel, a silicon deposition feedstock gas can be reacted efficiently even when the reaction vessel is scaled up to industrial large-scale equipment, generation of silicon fine powder and silane oligomers can be suppressed, and industrial silicon production can be performed over extended periods. The tubular reaction vessel comprises a longitudinally-extending wall with a space thereinside, wherein a silicon deposition feedstock gas inflow opening and a deposited silicon discharge opening are provided at an upper portion and a lower end portion respectively, and a flow resistance-increasing region is created on a wall surface of the tubular reaction vessel that is contacted with a feedstock gas. The flow resistance-increasing region is at least one of protrudent, concave and sloped regions.

Abstract: There is provided a silicon production method which comprises producing semiconductor grade silicon while producing solar grade silicon by converting a portion of trichlorosilane into silicon for solar cells. There is also provided an industrially advantageous method that removes contaminants from a chlorosilane circulating system which produces trichlorosilane in producing silicon from trichlorosilane by a vapor deposition method.

Abstract: A silicon production reactor including a reaction vessel and heating element, the reaction vessel has a vertically extending wall and a space surrounded by the wall, the heating element being capable of heating at least a part, including lower end portion, of the wall's surface facing the space to a temperature of not lower than the melting point of silicon, the silicon production reactor being adapted to flow raw gas for silicon deposition from an upper part of the space of the reaction vessel toward a lower part thereof, characterized in that the space of the reaction vessel is of slit form in cross-sectional view. This silicon production reactor is capable of attaining improvement with respect to problems encountered at apparatus scale-up, such as decrease of reactivity of raw gas and generation of by-products, thereby accomplishing a striking enhancement of production efficiency.

Abstract: It is an object to provide a silicon manufacturing apparatus that suppresses a silicon deposition to the bottom end portion of the reaction vessel and to a section other than the inside face of the reaction vessel except for the bottom end portion, thereby enabling a stable operation for a long time, for a silicon manufacturing apparatus that introduces a reaction gas to the inside wall of the heated reaction vessel to deposit silicon and that withdraws the deposited silicon from an opening at the bottom end portion of the reaction vessel. A first gas supply port 31 that is formed by a circular slit and that supplies a sealing gas and/or an etching gas to the bottom end portion is formed on the peripheral side around the bottom end portion of the reaction vessel.

Abstract: A solidified mass for a high-purity multicrystal silicon material that is preferably applicable to producing crystal type silicon ingots for photo voltaics, and a process for producing the solidified mass are provided. The mass of silicon solidified from molten state is a solidified mass produced by dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, said solidified mass containing bubbles and having (i) an apparent density of not less than 1.5 g/cm3 and not more than 2.2 g/cm3 and (ii) a compressive strength of not less than 5 MPa and not more than 50 MPa. The process for producing a mass of silicon solidified from molten state includes the steps of dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, wherein the surface temperature of the vessel for receiving the molten silicon is not lower than 0° C. and not higher than 1000° C.