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.

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.

There is provided a multi-layered membrane comprising a top layer, a bottom layer, and a spacer layer; wherein said spacer layer is interposed between said top layer and said bottom layer; wherein said top layer, said bottom layer and said spacer layer are each independently composed of one or more selective layers, each selective layer comprising a 2D material; wherein said spacer layer comprises at least one channel for receiving a fluid; wherein said bottom layer comprises a hole with an area in the range of 1 μm.sup.2 to 1 mm.sup.2; and wherein said hole is capable of being in fluid communication with said at least one channels of said spacer layer.

There is also provided a method to synthesize the top layer of a multi-layered membrane as disclosed herein, methods for separating a plurality of ions or molecules in a fluid stream, a device comprising a multi-layered membrane as disclosed herein, and use of the method or the device as disclosed herein in osmotic power generation.

A device for rapidly preparing β-Si3N4 by gas-solid reaction and a method thereof, and relates to the technical field of recycling and reuse of waste fine silicon powder. The bottom of a stock bin communicates with a first opening and closing passage, a first connection passage, and the top of a first transitional bin; the bottom of the first transitional bin communicates with the first opening and closing passage, a second connection passage, and the top of a reaction bin; the bottom of the reaction bin communicates with a second opening and closing passage, the first connection passage, and the top of a second transitional bin; the bottom of the second transitional bin communicates with the top of a conveying passage through the first opening and closing passage; a material outlet of the conveying bin communicates with the collection bin.

A process of producing silicon-containing materials includes converting a gas to a superheated state in which it is at least partly in plasma form, and contacting the superheated gas with a silicon-containing first starting material to form a mixture including the gas and silicon, wherein the silicon-containing materials are produced by adding to the gas or the mixture a second starting material that can enter into a chemical reaction directly with the silicon in the mixture, or breaks down thermally on contact with the superheated gas and/or the mixture, and steps a. and b. are effected spatially separately from one another.

A silicon nitride substrate including a first surface, and a second surface disposed opposite the first surface. One of the first surface or the second surface is a measurement surface. On the measurement surface, a value of an average full-width-at-half-maximum (FWHM) C.sub.ave is broader than 0 cm.sup.−1 and narrower than 5.32 cm.sup.−1 as measured by using a following measurement method. The measurement method of the average full-width-at-half-maximum (FWHM) C.sub.ave: one central point and four edge portions on the measurement surface are determined as measurement points; a Raman spectrum is measured at each of the measurement points; a full-width-at-half-maximum (FWHM) C of a spectral peak having the maximum strength within a range from 850 cm.sup.−1 or greater to 875 cm.sup.−1 or less is calculated in each Raman spectrum; and an average value of thus calculated full-width-at-half-maximum (FWHM)s C is the average full-width-at-half-maximum (FWHM) C.sub.ave.

Disclosed is a composition having nanoparticles or particles of a refractory metal, a refractory metal hydride, a refractory metal carbide, a refractory metal nitride, or a refractory metal boride, an organic compound consisting of carbon and hydrogen, and a nitrogenous compound consisting of carbon, nitrogen, and hydrogen. The composition, optionally containing the nitrogenous compound, is milled, cured to form a thermoset, compacted into a geometric shape, and heated in a nitrogen atmosphere at a temperature that forms a nanoparticle composition comprising nanoparticles of metal nitride and optionally metal carbide. The nanoparticles have a uniform distribution of the nitride or carbide.

A synthesis method of silicon nitride powder including preparing mixed powder having a particle size of 8 to 10 .Math.m which includes 69 to 98 wt% of silicon powder, 1 to 30 wt% of α-phase silicon nitride powder, and 1 to 10 wt% of silicon dioxide powder; performing heat treatment on the mixed powder in a nitrogen gas atmosphere of 0.85 to 1 atm at a temperature of 1,450 to 1,750° C. for 5 to 20 hours; and cooling the mixed powder gradually to obtain silicon nitride powder,; and performing pressure sintering on a silicon nitride sintered body by filling the mixed powder into a mold and then keeping the mixed powder at a temperature of 1,750 to 1,850° C. for 2 to 6 hours while pressure of 150 to 300 kg/cm.sup.2 is applied thereto in a nitrogen gas atmosphere of 0.85 to 1 atm.

A device for rapidly preparing β-Si3N4 by gas-solid reaction and a method thereof, and relates to the technical field of recycling and reuse of waste fine silicon powder. The bottom of a stock bin communicates with a first opening and closing passage, a first connection passage, and the top of a first transitional bin; the bottom of the first transitional bin communicates with the first opening and closing passage, a second connection passage, and the top of a reaction bin; the bottom of the reaction bin communicates with a second opening and closing passage, the first connection passage, and the top of a second transitional bin; the bottom of the second transitional bin communicates with the top of a conveying passage through the first opening and closing passage; a material outlet of the conveying bin communicates with the collection bin.

Disclosed is a composition having nanoparticles or particles of a refractory metal, a refractory metal hydride, a refractory metal carbide, a refractory metal nitride, or a refractory metal boride, an organic compound consisting of carbon and hydrogen, and a nitrogenous compound consisting of carbon, nitrogen, and hydrogen. The composition, optionally containing the nitrogenous compound, is milled, cured to form a thermoset, compacted into a geometric shape, and heated in a nitrogen atmosphere at a temperature that forms a nanoparticle composition comprising nanoparticles of metal nitride and optionally metal carbide. The nanoparticles have a uniform distribution of the nitride or carbide.