A method of preparing a boron nitride material, such as boron nitride (BN) or boron carbonitride (BCN), is provided. The method may include providing a substrate, and sublimating an amine borane complex onto the substrate to obtain the boron nitride material. The amine borane complex may include, but is not limited to, borazine, amino borane, trimethylamine borane and triethylamine borane. In addition, the temperature at which the sublimating is carried out may be varied to control composition of the boron nitride material formed. In addition, various morphologies can be obtained by using the present method, namely films, nanotubes and porous foam.

Nanotube filaments comprising carbon, boron and nitrogen of the general formula B.sub.xC.sub.yN.sub.z, having high-aspect ratio and high-crystallinity produced by a pressurized vapor/condenser method and a process of production. The process comprises thermally exciting a boron-containing target in a chamber containing a carbon source and nitrogen at a pressure which is elevated above atmospheric pressure.

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.

Methods for fabricating a ceramic matrix composite are disclosed. A fiber preform may be placed in a mold. An aqueous solution may be added to the fiber preform. The aqueous solution may include water, carbon nanotubes, and a binder. The preform may be frozen. Freezing the preform may cause the water to expand and separate fibers in the fiber preform. The carbon nanotubes may bond to the fibers. The preform may be freeze dried to remove the water. The preform may then be processed according to standard CMC process.

A multi-composition fiber is provided including a primary fiber material and an elemental additive material deposited on grain boundaries between adjacent crystalline domains of the primary fiber material. A method of making a multi-composition fiber is also provided, which includes providing a precursor laden environment, and promoting fiber growth using laser heating. The precursor laden environment includes a primary precursor material and an elemental precursor material.

Methods for fabricating a ceramic matrix composite are disclosed. A fiber preform may be placed in a mold. An aqueous solution may be added to the fiber preform. The aqueous solution may include water, carbon nanotubes, and a binder. The preform may be frozen. Freezing the preform may cause the water to expand and separate fibers in the fiber preform. The carbon nanotubes may bond to the fibers. The preform may be freeze dried to remove the water. The preform may then be processed according to standard CMC process.

A multi-component or composite inorganic fiber comprising a nano-scale contiguous collection of a plurality of packed unique phases of material randomly interspersed throughout the fiber body, without unwanted impurities, and a method for producing same. Said phases include three or more foundational chemical elements from the Periodic Table mixed together during fiber production, producing distinct material phases interspersed throughout the fiber volume.

The processes and products described herein optimize transformation of BNNT as-synthesized material into BNNT intermediary materials. Process steps include refining to remove boron particulates, high temperature refining to break bonds between BNNT, h-BN nanocages, h-BN nanosheets and amorphous BN particles, centrifuging and microfluidic separation, and electrophoresis. Resultant BNNT intermediary materials include purified BNNT in solution, BNNT gels, h-BN nanocages, and h-BN nanosheets, gel spun BNNT fibers, hydrophilic defect enhanced BNNT materials, BNNT patterned sheets, and BNNT strands. Applications that will utilize these BNNT precursor feedstock materials include making BNNT based aligned components, thin films, aerogels, thermal conductivity enhancements, structural materials, ceramic, metal, and polymer composites, and removal of PFAS pollutants from water.

Methods of growing boron nitride nanotubes and silicon nanowires on carbon substrates formed from carbon fibers. The methods include applying a catalyst solution to the carbon substrate and heating the catalyst coated carbon substrate in a furnace in the presence of chemical vapor deposition reactive species to form the boron nitride nanotubes and silicon nanowires. A mixture of a first vapor deposition precursor formed from boric acid and urea and a second vapor deposition precursor formed from iron nitrate, magnesium nitrate, and D-sorbitol are provided to the furnace to form boron nitride nanotubes. A silicon source including SiH.sub.4 is provided to the furnace at atmospheric pressure to form silicon nanowires.