An hBN powder containing an aggregate of primary particles of hBN, the hBN powder having a ratio of an average longer diameter (L.sub.1) to an average thickness (d.sub.1) of the primary particles, [L.sub.1/d.sub.1], of 10 to 25, a tap density of 0.80 g/cm.sup.3 or more, and a BET specific surface area of less than 5.0 m.sup.2/g, in which a particle size distribution curve showing a frequency distribution based on volume of the hBN powder is a bimodal distribution curve having a first peak and a second peak in a range of a particle size of 500 m or less and having a peak height ratio of a second peak height (H.sub.B) to a first peak height (H.sub.A), [(H.sub.B)/(H.sub.A)], of 0.90 or less, a method for producing the same, and a resin composition and a resin sheet each comprising the hBN powder.

Apparatus and methods of use thereof for the production of carbon-based and other nanostructures, as well as fuels and reformed products, are provided.

A powder boronizing composition comprising: a. 0.5 to 4.5 wt % of a boron source selected from B.sub.4C, amorphous boron, calcium hexaboride, borax or mixtures thereof; b. 45.5 to 88.5 wt % of a diluent selected from SiC, alumina or mixtures thereof; c. 1.0 to 20.0 wt % of an activator selected from KBF.sub.4, ammonia chloride, cryolite or mixtures thereof; and d. 10.0 to 30.0 wt % of a sintering reduction agent selected from carbon black, graphite or mixtures thereof.

A powder boronizing composition comprising: a. 0.5 to 4.5 wt % of a boron source selected from B.sub.4C, amorphous boron, calcium hexaboride, borax or mixtures thereof; b. 45.5 to 88.5 wt % of a diluent selected from SiC, alumina or mixtures thereof; c. 1.0 to 20.0 wt % of an activator selected from KBF.sub.4, ammonia chloride, cryolite or mixtures thereof; and d. 10.0 to 30.0 wt % of a sintering reduction agent selected from carbon black, graphite or mixtures thereof.

A process comprising: placing a boronizing powder composition in the interior of a metal pipe comprising a first end, a second end, an inside surface and an outside surface; heating the pipe in a vessel having an interior, to a temperature from 1400 F. to 1900 F., thereby forming spent boronizing reaction gases and a borided layer on the inside surface, wherein the vessel interior has an atmosphere that surrounds the outside surface of the metal pipe; and flowing the spent boronizing reaction gases into the atmosphere surrounding the outside surface of the pipe, thereby forming an oxygen-depleted atmosphere.

Three-dimensional nanoporous aerogels and suitable preparation methods are provided. Nanoporous aerogels may include a carbide material such as a silicon carbide, a metal carbide, or a metalloid carbide. Elemental (e.g., metallic or metalloid) aerogels may also be produced. In some embodiments, a cross-linked aerogel having a conformal coating on a sol-gel material is processed to form a carbide aerogel, metal aerogel, or metalloid aerogel. A three-dimensional nanoporous network may include a free radical initiator that reacts with a cross-linking agent to form the cross-linked aerogel. The cross-linked aerogel may be chemically aromatized and chemically carbonized to form a carbon-coated aerogel. The carbon-coated aerogel may be suitably processed to undergo a carbothermal reduction, yielding an aerogel where oxygen is chemically extracted. Residual carbon remaining on the surface of the aerogel may be removed via an appropriate cleaning treatment.

The carbon nanotube pellets according to the present invention are produced by using only a small amount of solvent and have increased apparent density. The present invention can improve the problems of the change of the content generated by scattering of powders and safety issues by using carbon nanotubes in the form of pellet rather than carbon nanotubes in the form of powder in composite materials. And since the density of the pellet form is higher than that of the powder form, transport, transfer and improvement become easier. Therefore, it can be more effectively applied to the manufacturing of composite materials.

Three-dimensional nanoporous aerogels and suitable preparation methods are provided. Nanoporous aerogels may include a carbide material such as a silicon carbide, a metal carbide, or a metalloid carbide. Elemental (e.g., metallic or metalloid) aerogels may also be produced. In some embodiments, a cross-linked aerogel having a conformal coating on a sol-gel material is processed to form a carbide aerogel, metal aerogel, or metalloid aerogel. A three-dimensional nanoporous network may include a free radical initiator that reacts with a cross-linking agent to form the cross-linked aerogel. The cross-linked aerogel may be chemically aromatized and chemically carbonized to form a carbon-coated aerogel. The carbon-coated aerogel may be suitably processed to undergo a carbothermal reduction, yielding an aerogel where oxygen is chemically extracted. Residual carbon remaining on the surface of the aerogel may be removed via an appropriate cleaning treatment.

Three-dimensional nanoporous aerogels and suitable preparation methods are provided. Nanoporous aerogels may include a carbide material such as a silicon carbide, a metal carbide, or a metalloid carbide. Elemental (e.g., metallic or metalloid) aerogels may also be produced. In some embodiments, a cross-linked aerogel having a conformal coating on a sol-gel material is processed to form a carbide aerogel, metal aerogel, or metalloid aerogel. A three-dimensional nanoporous network may include a free radical initiator that reacts with a cross-linking agent to form the cross-linked aerogel. The cross-linked aerogel may be chemically aromatized and chemically carbonized to form a carbon-coated aerogel. The carbon-coated aerogel may be suitably processed to undergo a carbothermal reduction, yielding an aerogel where oxygen is chemically extracted. Residual carbon remaining on the surface of the aerogel may be removed via an appropriate cleaning treatment.

The present invention relates to a process for the preparation of boron carbide nanoparticles, characterized in that it comprises at least the stages consisting in: (i) interacting boric acid, boron oxide B.sub.2O.sub.3 or a boric acid ester of B(OR).sub.3 type, with R, which are identical or different, representing C.sub.1-4-alkyl groups, with 1 to 2 molar equivalents of at least one C.sub.2 to C.sub.4 polyol, under conditions favorable to the formation of a boron alkoxide powder; (ii) interacting, in an aqueous medium, the boron alkoxide powder obtained on conclusion of stage (i) with an effective amount of one or more completely hydrolyzed polyvinyl alcohols, with a molar mass of between 10 000 and 80 000 g.mol.sup.1, under conditions favorable to the formation of a crosslinked PVA gel, and (iii) carrying out an oxidizing pyrolysis of the crosslinked gel formed on conclusion of the preceding stage (ii), under conditions favorable to the formation of the CB.sub.4 nanoparticles.