Provided are a dispersion for a silicon carbide sintered body having a small environmental load, high dispersibility, and excellent temporal stability, and a manufacturing method thereof. The dispersion is a dispersion for a silicon carbide sintered body, containing: silicon carbide particles; boron nitride particles; a resin having a hydroxyl group; and water, wherein the dispersion has a pH at 25° C. of less than or equal to 7.0, and the silicon carbide particles and the boron nitride particles have charges of the same sign. The dispersion is manufactured by a manufacturing method of a dispersion for a silicon carbide sintered body, including a mixing step of mixing a water dispersion containing silicon carbide particles, a water dispersion containing boron nitride particles, and an aqueous solution containing a resin having a hydroxyl group.

High quality, catalyst-free boron nitride nanotubes (BNNTs) that are long, flexible, have few wall molecules and few defects in the crystalline structure, can be efficiently produced by a process driven primarily by Direct Induction. Secondary Direct Induction coils, Direct Current heaters, lasers, and electric arcs can provide additional heating to tailor the processes and enhance the quality of the BNNTs while reducing impurities. Heating the initial boron feed stock to temperatures causing it to act as an electrical conductor can be achieved by including refractory metals in the initial boron feed stock, and providing additional heat via lasers or electric arcs. Direct Induction processes may be energy efficient and sustainable for indefinite period of time. Careful heat and gas flow profile management may be used to enhance production of high quality BNNT at significant production rates.

A polycrystalline cubic boron nitride comprising 96% by volume or more of cubic boron nitride, wherein the cubic boron nitride has a dislocation density of 8×10.sup.15/m.sup.2 or less, the polycrystalline cubic boron nitride comprises a plurality of crystal grains, and the plurality of crystal grains have a median diameter d50 of an equivalent circle diameter of less than 100 nm.

Disclosed is a method of purifying boron nitride nanotubes through a simplified process. Specifically, the method includes preparing a starting solution containing boron nitride nanotubes (BNNTs), a dispersant and a solvent, centrifuging the starting solution or allowing the starting solution to stand to collect a supernatant, adding an acid to the supernatant and filtering a resulting product.

The present disclosure provides a method for preparing a multi-layer hexagonal boron nitride film, including: preparing a substrate; preparing a boron-containing solid catalyst, and disposing the boron-containing solid catalyst on the substrate; annealing the boron-containing solid catalyst to melt the boron-containing solid catalyst; feeding a nitrogen-containing gas and a protecting gas to an atmosphere in which the melted boron-containing solid catalyst resides, the nitrogen-containing gas reacts with the boron-containing solid catalyst to form the multi-layer hexagonal boron nitride film on a surface of the substrate. The method for preparing a multi-layer hexagonal boron nitride film can prepare a hexagonal boron nitride film having a lateral size in the order of inches and a thickness from several nanometers to several hundred nanometers on the surface of the substrate, providing a favorable basis for the application of hexagonal boron nitride in the field of two-dimensional material devices.

The present disclosure provides a method for preparing a multi-layer hexagonal boron nitride film, including: preparing a substrate; preparing a boron-containing solid catalyst, and disposing the boron-containing solid catalyst on the substrate; annealing the boron-containing solid catalyst to melt the boron-containing solid catalyst; feeding a nitrogen-containing gas and a protecting gas to an atmosphere in which the melted boron-containing solid catalyst resides, the nitrogen-containing gas reacts with the boron-containing solid catalyst to form the multi-layer hexagonal boron nitride film on a surface of the substrate. The method for preparing a multi-layer hexagonal boron nitride film can prepare a hexagonal boron nitride film having a lateral size in the order of inches and a thickness from several nanometers to several hundred nanometers on the surface of the substrate, providing a favorable basis for the application of hexagonal boron nitride in the field of two-dimensional material devices.

An agglomerated boron nitride powder, including a tap density of 0.6 g/ml or more and less than 0.8 g/ml and an interparticle void volume of 0.5 ml/g or more. A heat dissipation sheet, including the agglomerated boron nitride powder. An agglomerated boron nitride powder that enables a heat dissipation sheet to have improved thermal conductivity and good withstand voltage characteristics, a heat dissipation sheet containing the agglomerated boron nitride powder, and a semiconductor device including the heat dissipation sheet are provided.

An agglomerated boron nitride powder, including a tap density of 0.6 g/ml or more and less than 0.8 g/ml and an interparticle void volume of 0.5 ml/g or more. A heat dissipation sheet, including the agglomerated boron nitride powder. An agglomerated boron nitride powder that enables a heat dissipation sheet to have improved thermal conductivity and good withstand voltage characteristics, a heat dissipation sheet containing the agglomerated boron nitride powder, and a semiconductor device including the heat dissipation sheet are provided.

The present disclosure provides a method for producing a boron nitride nanotube by heating a boron precursor, and an apparatus therefor. According to an embodiment, a method of producing a boron nitride nanotube includes: inserting several reaction modules each accommodating a holding rod disposed through at least one precursor block into a supply chamber disposed at a front end of a reaction chamber; conveying N reaction modules of the several reaction modules inserted in the supply chamber to a reaction zone of the reaction chamber; growing a boron nitride nanotube in the precursor block by operating the reaction zone for a predetermined time, in the reaction chamber; and conveying the N reaction modules from the reaction chamber to a discharge chamber disposed at a rear end of the reaction chamber after the predetermined time passes. Accordingly, it is possible to maximize the yield and productivity of BNNTs.

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.