A -SiC coating made by the method of mixing SiO.sub.2 with carbon and heating the mixture in vacuum wherein the carbon is oxidized to CO gas and reduces the SiO.sub.2 to SiO gas and reacting a carbon material, comprising stainless steel with a carbon coating, with the SiO gas at a temperature in the range of 1300 to 1600 C. resulting in a SiC coating on the stainless steel.

A -SiC coating made by the method of mixing SiO.sub.2 with carbon and heating the mixture in vacuum wherein the carbon is oxidized to CO gas and reduces the SiO.sub.2 to SiO gas and reacting a carbon material, comprising stainless steel with a carbon coating, with the SiO gas at a temperature in the range of 1300 to 1600 C. resulting in a SiC coating on the stainless steel.

A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000 C. to 1600 C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000 C. to 1600 C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

A method of preparing silicon carbide according to the present invention includes reacting a silicon-containing compound with carbon dioxide, wherein a reducing agent is optionally used.

A method of preparing silicon carbide according to the present invention includes reacting a silicon-containing compound with carbon dioxide, wherein a reducing agent is optionally used.

Porous three-dimensional networks of polyimide and porous three-dimensional networks of carbon and methods of their manufacture are described. For example, polyimide aerogels are prepared by mixing a dianhydride and a diisocyanate in a solvent comprising a pyrrolidone and acetonitrile at room temperature to form a sol-gel material and supercritically drying the sol-gel material to form the polyimide aerogel. Porous three-dimensional polyimide networks, such as polyimide aerogels, may also exhibit a fibrous morphology. Having a porous three-dimensional polyimide network undergo an additional step of pyrolysis may result in the three dimensional network being converted to a purely carbon skeleton, yielding a porous three-dimensional carbon network. The carbon network, having been derived from a fibrous polyimide network, may also exhibit a fibrous morphology.

Silicon particles for active materials and electro-chemical cells are provided. The active materials comprising silicon particles described herein can be utilized as an electrode material for a battery. In certain embodiments, the composite material includes greater than 0% and less than about 90% by weight silicon particles, the silicon particles having an average particle size between about 10 nm and about 40 m, wherein the silicon particles have surface coatings comprising silicon carbide or a mixture of carbon and silicon carbide, and greater than 0% and less than about 90% by weight of one or more types of carbon phases, wherein at least one of the one or more types of carbon phases is a substantially continuous phase.

A silicon carbide powder having silicon carbide particles including carbon and silicon, wherein a mass ratio of silicon carbide particles having a particle diameter of less than 50 m after sonication is 10 Wt % or less.

A method of producing ceramic wafer includes a forming step and processing step. The processing step includes forming positioning notch or positioning, flat edge and edge profile, which avoids the ceramic wafers to have processing defect during cutting, grinding, and polishing, for increasing yield. The ceramic particles for producing ceramic wafer include nitride ceramic powder, oxide ceramic powder, and nitride ceramic powder. The ceramic wafer has low dielectric constant, insulation, and excellent heat dissipation, which can be applied for the need of semiconductor process, producing electric product and semiconductor equipment.