摘要:
A method for making submicrometer metallic carbides and submicrometer solid solution metallic carbides from sources of at least one metallic oxide and carbon involves the rapid heating of a reactive particulate mixture of at least one metallic oxide and carbon in order to achieve a resulting particulate size of less than 1 micrometer. Submicrometer sized metallic carbides and solid solution metallic carbides have found great use in commercial ceramic applications. It has been found that the smaller sized particles produce a product having superior toughness and hardness. In addition, the submicrometer sized solid solution metallic carbide resulting from this method is also disclosed.
摘要:
Rapidly heat powdered aluminum in the presence of a source of nitrogen at a temperature of 1873 to 2373 K. to produce aluminum nitride, then promptly quench the aluminum nitride product. The product has a surface area between 2 and 8 square meters per gram and an oxygen content of less than 1.2 weight percent.
摘要:
Aluminum nitride powder, aluminum nitride platelets, powdered solid solutions of aluminum nitride and at least one other ceramic material such as silicon carbide, and composites of aluminum nitride and transition metal borides or carbides are prepared by combustion synthesis at low gaseous nitrogen pressures. Porous bodies of aluminum nitride or composites of aluminum nitride and transition metal borides or carbides are also prepared by combustion synthesis at these pressures. The porous bodies are suitable for infiltration, either as formed or after being coated with at least one layer of a silicate material, by polymers or metals. The powders are also suitable for preparing dense sintered bodies. The aluminum nitride powder is also used to prepare AlN sintered bodies.
摘要:
A method for forming monotungsten carbide, comprising heating a solid, non-elemental tungsten-containing material in a flowing atmosphere containing molecular hydrogen and molecular methane for a time sufficient to convert substantially all of the tungsten-containing material to monotungsten carbide, The heating brings the temperature of the tungsten-containing material to a first elevated temperature of from about 520 to about 550.degree. C. and, subsequently, at a rate of from about 3 to about 10.degree. C. per minute, the heating brings the temperature from the first elevated temperature to a second elevated temperature of about 800 to about 900.degree. C. Thereafter the temperature is held at the second elevated temperature for at least about 15 minutes. At least about 50 weight percent of the monotungsten carbide formed is formed while holding the temperature at the second elevated temperature.
摘要:
Aluminum nitride powder, aluminum nitride platelets, powdered solid solutions of aluminum nitride and at least one other ceramic material such as silicon carbide, and composites of aluminum nitride and transition metal borides or carbides are prepared by combustion synthesis at low gaseous nitrogen pressures. Porous bodies of aluminum nitride or composites of aluminum nitride and transition metal borides or carbides are also prepared by combustion synthesis at these pressures. The porous bodies are suitable for infiltration, either as formed or after being coated with at least one layer of a silicate material, by polymers or metals.
摘要:
A process for preparing silicon carbide by carbothermal reduction is disclosed. This process involves rapidly heating a particulate reactive mixture of a silica source and a carbon source to form a product which shows improved uniformity of crystal size. The product of this process can be used to form a densified part.
摘要:
Uniform, fine ceramic powder is prepared using an apparatus comprising (a) a cooled reactant transport member; (b) a reactor chamber; (c) a heating means; and (d) a cooling chamber. The reactant transport member comprises a wall defining a conduit that communicates with the reactor chamber, with a gas-flow space being defined along the perimeter of the transport member and in communication with the reactor chamber. The reactor chamber comprises a wall defining a reaction zone, and the heating means is associated with the reaction zone, and adapted for heating reactants in the reaction zone. The cooling chamber comprises a wall defining a cooling zone that communicates with the reactor chamber. In one embodiment the communication is by means of a cooling inlet, the diameter of the cooling zone being larger than the diameter of the cooling inlet. The temperatures of the reactant transport member, the reactor chamber, and the cooling chamber are independently controllable. Reactants can be fed through the reactant transport member into the reaction zone and reacted to form products, and the products then fed into the cooling zone to produce uniform, fine ceramic powders.
摘要:
Uniform, fine ceramic powder is prepared using an apparatus comprising (a) a cooled reactant transport member; (b) a reactor chamber; (c) a heating element; and (d) a cooling chamber. The reactant transport member comprises a wall defining a conduit that communicates with the reactor chamber, with a gas-flow space being defined along the perimeter of the transport member and in communication with the reactor chamber. The reactor chamber comprises a wall defining a reaction zone, and the heating element is associated with the reaction zone, and adapted for heating reactants in the reaction zone. The cooling chamber has a wall defining a cooling zone that communicates with the reactor chamber. In one embodiment, the communication is through a cooling inlet, the diameter of the cooling zone being larger than the diameter of the cooling inlet. The temperatures of the reactant transport member, the reactor chamber, and the cooling chamber are independently controllable. Reactants can be fed through the reactant transport member into the reaction zone and reacted to form products, and the products then fed into the cooling zone to produce uniform, fine ceramic powders.
摘要:
The end turn region of a superconducting rotor is provided with end region support blocks that together provide channels for coil location. Within the support block channels there are intermittent supports in the form of insulating spacers extending radially both to the front and to the rear of the coil and also bottom spacers, with sheets of side insulation between the front and rear spacers and the adjacent support blocks. The intermittent supports provide access of coolant to the superconductor. They may also be formed in a manner to tilt the end region toward the pole piece for better mechanical support. A top insulating spacer is provided with cooling channels and is utilized with banding to provide secure compressive support for the end windings. Apertures in the support blocks and grooves in the spacers provide collant circulation.
摘要:
Systems and methods providing statistical analytics of golf performance including text, tabular, graphic, and image-based outputs that include trends information for the golfer, all based upon actual golf play on course situations, wherein the golfer inputs shot data during play, without interrupting the flow of the game, and uploads the shot data for analytics and review online, including detailed diagrammatic representations of golf performance analytics, including scattergraph diagrams having the directionality of any shot being uniformly and consistently oriented to provide a zeroed-out orientation for each shot.