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 production method of boron carbide nano-sized particles and/or submicron particles includes the following sequential steps: obtention of a fluid mixture including elemental boron, glycerin and one or more carboxylic acid, wherein a molar ratio of glycerin to the one or more carboxylic acids is within a range between 10:1 and 10:7.5. Heating of the fluid mixture to obtain a first mid-product in a form of a gel including borate ester bonds. Solidification of the first mid-product by heating a reaction product to obtain a second mid-product in solid form. Sintering the second mid-product to obtain boron carbide in a form of particles.

A silicon carbide porous body contains -SiC particles, Si particles, and metal silicide particles. The maximum particle diameter of the -SIC particles is not smaller than 15 m. The content of the Si particles is not lower than 10 mass %. The maximum particle diameter of the Si particles is not larger than 40 m. Further, an oxide coating film having a thickness not smaller than 0.01 m and not larger than 5 m is provided on surfaces of the Si particles.

A method for the manufacture of a carbon composite comprises compressing a combination comprising carbon and a binder at a temperature of about 350 C. to about 1200 C. and a pressure of about 500 psi to about 30,000 psi to form the carbon composite; wherein the binder comprises a nonmetal, metal, alloy of the metal, or a combination thereof wherein the nonmetal is selected from the group consisting of SiO.sub.2, Si, B, B.sub.2O.sub.3, and a combination thereof; and the metal is selected from the group consisting of aluminum, copper, titanium, nickel, tungsten, chromium, iron, manganese, zirconium, hafnium, vanadium, niobium, molybdenum, tin, bismuth, antimony, lead, cadmium, selenium, and a combination thereof.

Articles comprising carbon composites are disclosed. The carbon composites contain carbon microstructures having interstitial spaces among the carbon microstructures; and a binder disposed in at least some of the interstitial spaces; wherein the carbon microstructures comprise unfilled voids within the carbon microstructures. Alternatively, the carbon composites contain: at least two carbon microstructures; and a binding phase disposed between the at least two carbon microstructures; wherein the binding phase comprises a binder comprising one or more of the following: SiO.sub.2; Si; B; B.sub.2O.sub.3; a metal; or an alloy of the metal; and wherein the metal is at least one of aluminum; copper; titanium; nickel; tungsten; chromium; iron; manganese; zirconium; hafnium; vanadium; niobium; molybdenum; tin; bismuth; antimony; lead; cadmium; or selenium.

A method for manufacturing a magnesium-based thermoelectric conversion material of the present invention includes a raw material-forming step of forming a raw material for sintering by adding silicon oxide in an amount within a range equal to or greater than 0.5 mol % and equal to or smaller than 13.0 mol % to a magnesium-based compound, and a sintering step of heating the raw material for sintering at a temperature within a range equal to or higher than 750 C. and equal to or lower than 950 C. while applying pressure equal to or higher than 10 MPa to the raw material for sintering so as to form a sintered substance.

A material including a body including B.sub.6O.sub.X can include lattice constant c of at most 12.318. X can be at least 0.85 and at most 1. In a particular embodiment, 0.90X1. In another particular embodiment, lattice constant a can be at least 5.383 and lattice constant c can be at most 12.318. In another particular embodiment, the body can consist essentially of B.sub.6O.sub.X.

A method of making a carbon-carbon composite part may comprise fabricating a fibrous preform comprising a fiber volume ratio of 25% or greater, heat treating the fibrous preform at a first temperature, infiltrating the fibrous preform with a first ceramic suspension, densifying the fibrous preform by chemical vapor infiltration (CVI) to form a densified fibrous preform, and heat treating the densified fibrous preform at a second temperature of 1600 C. or greater.

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 BN-NTs 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, or providing additional heat via lasers or electric arcs. Direct Induction processes may be energy efficient and sustainable for indefinite periods of time. Careful heat and gas flow profile management may be used to enhance production of high quality BNNT at significant production rates.

The present invention relates to a method for making a hexagonal boron nitride slurry and the resulting slurry. The method involves mixing from about 0.5 wt. % to about 5 wt. % surfactant with about 30 wt. % to about 50 wt. % hexagonal boron nitride powder in a medium under conditions effective to produce a hexagonal boron nitride slurry. The present invention also relates to a method for making a spherical boron nitride powder and a method for making a hexagonal boron nitride paste using a hexagonal boron nitride slurry. Another aspect of the present invention relates to a hexagonal boron nitride paste including from about 60 wt. % to about 80 wt. % solid hexagonal boron nitride. Yet another aspect of the present invention relates to a spherical boron nitride powder, a polymer blend including a polymer and the spherical hexagonal boron nitride powder, and a system including such a polymer blend.