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.

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.

Inside a furnace body with a vacuum environment or under the inert gas protection, the raw silicon material used to produce silicon carbide is melted or vaporized in a high temperature environment over 1300 C., and then the melted or vaporized raw silicon material will react with the carbonaceous gas or liquid to form silicon carbide. The present invention uses the carbonaceous gas with no metallic impurities, to replace petroleum coke, resin, asphalt, graphite, carbon fiber, coal, charcoal and some other carbon sources used in current production processes. When the carburizing reaction is in progress, the raw silicon material is melted or vaporized and the reaction takes place in the air. No container is required, so impurity contamination is lessened, and the produced silicon carbide has a fairly high purity.

The present invention relates to a method of preparing ultra-pure silicon carbide in which a super-porous spherical silica aerogel is used as a silica raw material. By preparing the silica aerogel particles using low-cost water glass, a reaction area with respect to a carbon raw material is increased to enable low-temperature synthesis of silicon carbide, the size and shape of silicon carbide powder may be uniformly controlled to prepare ultra-pure silicon carbide, and economic efficiency and productivity of the silicon carbide synthesis may be improved. Thus, it is expected that the silicon carbide powder prepared by the preparation method of the present invention may be provided as an optimized raw material for the preparation of silicon carbide sintered body and single crystal (ingot).

The present invention relates to a method of preparing ultra-pure silicon carbide in which a super-porous spherical silica aerogel is used as a silica raw material. By preparing the silica aerogel particles using low-cost water glass, a reaction area with respect to a carbon raw material is increased to enable low-temperature synthesis of silicon carbide, the size and shape of silicon carbide powder may be uniformly controlled to prepare ultra-pure silicon carbide, and economic efficiency and productivity of the silicon carbide synthesis may be improved. Thus, it is expected that the silicon carbide powder prepared by the preparation method of the present invention may be provided as an optimized raw material for the preparation of silicon carbide sintered body and single crystal (ingot).

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 can include reducing a silica starting material to produce a first quantity of at least metallurgical grade silicon and a second quantity of silica comprising elemental carbon doping, wherein the silica starting material is reduced in the presence of a carbonaceous reducing agent. A silica material can be a silica material as prepared according to the method.

[Problem] To provide a practical solid polymer fuel cell having high cell performance and excellent durability.

[Means for solving] The polymer electrolyte fuel cell according to the present invention includes: a membrane electrode assembly in which electrodes each including a catalyst layer are joined to both surfaces of an electrolyte membrane; and a peroxide decomposition catalyst which is fixed to the electrolyte membrane and/or the electrodes and includes a hardly soluble carbide, a boride, and/or a silicide. The peroxide decomposition catalyst preferably contains a carbide, a boride and/or a silicide of a rare earth element, a transition metal element or a typical metal element.

[Problem] To provide a practical solid polymer fuel cell having high cell performance and excellent durability.

[Means for solving] The polymer electrolyte fuel cell according to the present invention includes: a membrane electrode assembly in which electrodes each including a catalyst layer are joined to both surfaces of an electrolyte membrane; and a peroxide decomposition catalyst which is fixed to the electrolyte membrane and/or the electrodes and includes a hardly soluble carbide, a boride, and/or a silicide. The peroxide decomposition catalyst preferably contains a carbide, a boride and/or a silicide of a rare earth element, a transition metal element or a typical metal element.

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.