An electrostatic chuck is provided. Implemented according to an embodiment of the present invention is an electrostatic chuck comprising: a silicon nitride sintered body; a surface modification layer covering at least a portion of the external surface of the silicon nitride sintered body and having corrosion resistance and plasma resistance; and an electrostatic electrode laid inside the silicon nitride sintered body. Therefore, the electrostatic chuck includes a ceramic sintered body of silicon nitride, and thus has excellent plasma resistance, chemical resistance, and thermal shock resistance while exhibiting an equivalent or similar level of heat dissipation performance compared to ceramic sintered bodies of aluminum nitride that have been conventionally widely used, so that the electrostatic chuck can be widely used in semiconductor processes.

Ceramic composite materials that are reinforced with carbide fibers can exhibit ultra-high temperature resistance. For example, such materials may exhibit very low creep at temperatures of up to 2700 F. (1480 C.). The present composites are specifically engineered to exhibit matched thermodynamically stable crystalline phases between the materials included within the composite. In other words, the reinforcing fibers, a debonding interface layer disposed over the reinforcing fibers, and the matrix material of the composite may all be of the same crystalline structural phase (all hexagonal), for increased compatibility and improved properties. Such composite materials may be used in numerous applications.

Methods for producing wavelength converters are described. The methods include sintering a mixture consisting essentially of first particles and second particles to form a sintered article. In embodiments the first particles consist essentially of particles of -SiAlON or precursors thereof, and the second particles consist essentially one or more sintering aids or precursors thereof. In embodiments the sintered article has a density that is greater than or equal to about 90% of a theoretical bulk density of the mixture, and is configured to convert primary light incident thereon to secondary light, wherein the secondary light exhibits a peak with a full width half maximum of greater than 0 to about 60 nanometers (nm) within a wavelength range of about 495 nm to about 600 nm.

A sintered material includes a first material and a second material, the first material being partially stabilized ZrO.sub.2 having a crystal grain boundary or crystal grain in which 5 to 90 volume % of Al.sub.2O.sub.3 is dispersed with respect to a whole of the first material, the second material including at least one of SiAlON, silicon nitride and titanium nitride, the sintered material including 1 to 50 volume % of the first material.

A production process for a crystal oriented ceramics includes: a first step of preparing composite particles formed of particles having magnetic anisotropy having magnetic susceptibility anisotropy and seed particles having magnetic susceptibility anisotropy less than or equal to 1/10 of the magnetic susceptibility anisotropy of the particles having magnetic anisotropy and are formed of an inorganic compound having an anisotropic shape in which a crystal axis intended to be corresponds to a minor axis or a major axis; a second step of adding raw material powder including the composite particles to a solvent to prepare a slurry a third step of preparing a green compact by disposing the slurry in a static magnetic field of >0.1 tesla and drying the slurry in a state in which crystal axes of the seed particles in a major axis direction are in one direction; and a fourth step of sintering the green compact.

To provide a silicon nitride sintered body, a machine part and a bearing that have superior mechanical properties and sliding properties. A rolling element 4 is a silicon nitride sintered body including a silicon nitride particle, a rare earth element and an aluminum element. In a range in which the sum of the area of the upper-size crystal grain diameter within a range where the crystal grain diameter of a -type Si.sub.3N.sub.4 particle in the silicon nitride sintered body has the crystal orientation of 15-180 degrees, is 30% relative to an area of the total crystal grain diameter, the crystal grain diameter of the -type Si.sub.3N.sub.4 particle is 1-4 m by circle equivalent diameter and/or the aspect ratio of the -type Si.sub.3N.sub.4 particle is 3-6.

A silicon nitride sintered body according to an embodiment includes not less than 0.1 mass % and not more than 10 mass % of zirconium when converted to oxide. In XRD analysis (2) of any cross section of the silicon nitride sintered body, 0.01I.sub.35.3/I.sub.27.00.5 and 0I.sub.33.9/I.sub.27.01.0 are satisfied; I.sub.35.3 is a maximum peak intensity detected at 35.30.2 based on -silicon nitride crystal grains; I.sub.27.0 is a most intense peak detected at 27.00.2 based on -silicon nitride crystal grains; and I.sub.33.9 is a most intense peak detected at 33.90.2 based on zirconium nitride.

The present invention provides a silicon nitride wear resistant member comprising a silicon nitride sintered compact containing -Si.sub.3N.sub.4 crystal grains as a main component, 2 to 4% by mass of a rare earth element in terms of oxide, 2 to 6% by mass of Al in terms of oxide, and 0.1 to 5% by mass of Hf in terms of oxide, wherein the silicon nitride sintered compact has rare earth-HfO compound crystals; in an arbitrary section, an area ratio of the rare earth-HfO compound crystals in a grain boundary phase per unit area of 30 m30 m is 5 to 50%; and variation of the area ratios of the rare earth-HfO compound crystals between the unit areas is 10% or less. Due to above structure, there can be provided a wear resistant member comprising the silicon nitride sintered compact having an excellent wear resistance and processability.

A silicon nitride powder having a specific surface area of 4.0 to 9.0 m.sup.2/g, a phase proportion of less than 40 mass %, and an oxygen content of 0.20 to 0.95 mass %, wherein a frequency distribution curve obtained by measuring a volume-based particle size distribution by a laser diffraction scattering method has two peaks, peak tops of the peaks are present respectively at 0.4 to 0.7 m and 1.5 to 3.0 m, a ratio of frequencies of the peak tops ((frequency of the peak top in a particle diameter range of 0.4 to 0.7 m)/(frequency of the peak top in a particle diameter range of 1.5 to 3.0 m)) is 0.5 to 1.5, and a ratio D50/D.sub.BET (m/m) of a median diameter D50 (m) determined by the measurement of particle size distribution to a specific surface area-equivalent diameter D.sub.BET (m) calculated from the specific surface area is 3.5 or more.

Provided is a green sheet, comprising a raw material powder and a binder resin, in which the raw material powder contains a silicon nitride powder, and a glass transition temperature of the binder resin is less than 20 C.