A powder of gallium nitride has an oxygen content of 0.5 at or less. A green body formed by charging 8 g of the powder into a rectangular cuboidal die having a size of 10 mm40 mm and uniaxially pressing the powder at a pressure of 100 MPa has an electrical resistivity of 1.010.sup.7 .Math.cm or less.

A cubic boron nitride sintered material includes cubic boron nitride and a binder. The binder includes a first material and a second material. The first material is one or two or more first chemical species each including at least one first metallic element selected from the group consisting of tungsten, cobalt, and aluminum. Each of the first chemical species is a metal, an alloy, an intermetallic compound, a compound, or a solid solution. The second material is one or two or more second chemical species each including at least one second metallic element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, and chromium. Each of the second chemical species is a solid solution derived from at least one selected from the group consisting of nitride, carbide, and carbonitride. In each of the second chemical species, 0.1 atom % to 10 atom % of aluminum is dissolved.

The present invention relates to a porous alpha-SiC-containing shaped body with a gas-permeable, open-pored pore structure comprising platelet-shaped crystallites which are connected to form an interconnected, continuous skeletal structure, wherein the skeletal structure consists of more than 80 wt.-% alpha-SiC, relative to the total weight of SiC, a process for producing same and its use as a filter component.

The present invention related to a method to make capacitor grade powder. The method includes the use of a spray dryer that includes a rotating atomizer disk to form agglomerated powder and the method further includes a heat treatment step. Capacitor grade powder formed by the methods of the present invention are further described.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/rum or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.

A reactor useful in the production and conversion of hydrocarbon feedstocks may include: a pressure vessel with an interior wall; a refractory lining inside the reactor, wherein the refractory lining comprises: a first layer comprising a brick refractory, a second layer comprising a refractory castable, wherein the refractory castable comprises an aggregate and a binder, wherein the binder comprises CaO.Math.6Al.sub.2O.sub.3 and less than 1 wt % of a hydratable calcium aluminate, and a third layer comprising a fiber refractory, wherein the second layer is between the first and third layers, and wherein the third layer is closest to the interior wall.

A ceramic molded body including a ceramic powder and an organic binder includes an oxidizable ceramic powder as the ceramic powder, includes an oxidizable metal or metal compound, or is in contact with a solid body including an oxidizable metal or metal compound. In a hydrogen atmosphere, the ceramic molded body is heated to a maximum temperature set within a range of 1,100 C. to 1,400 C. at a heating rate of more than 25 C./h, is degreased at the maximum temperature, and is then cooled at a cooling rate of more than 25 C./h.

A method for producing a polysilane includes a disproportionation reaction of a methylchlorodisilane mixture to form chlorine-containing oligosilane, a substitution reaction of the chlorine atoms contained in the oligosilane by the reaction with a primary amine and a cross-linking reaction of the oligosilanes using a chain former to form polysilanes. The obtained polysilanes are infusible and are very suitable for being spun to form green fibers and processed to form silicon carbide fibers and fiber composites. The method is characterized in that it can be carried out cost-effectively and quickly and with very high yields.

The present invention relates to a porous alpha-SiC-containing shaped body with a gas-permeable, open-pored pore structure comprising platelet-shaped crystallites which are connected to form an interconnected, continuous skeletal structure, wherein the skeletal structure consists of more than 80 wt.-% alpha-SiC, relative to the total weight of SiC, a process for producing same and its use as a filter component.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/mm or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.