Provided is an aluminum nitride powder useful as a raw material when an aluminum nitride sintered body excellent as an insulating high thermal conductive member is manufactured, particularly, by press molding.

An aluminum nitride powder includes particles having a sphericity of 0.8 or more, in which a median size D.sub.50 obtained by a laser diffraction method is 0.5 to 1.5 μm, a ratio D.sub.90/D.sub.50 of a particle size D.sub.90 corresponding to a cumulative undersize distribution of 90% to the D.sub.50 is 2.2 or less, a BET specific surface area is 2 to 4 m.sup.2/g, and a total oxygen concentration is 0.6 to 1.2% by mass.

Crystal pulling systems having composite polycrystalline silicon feed tubes, methods for forming such tubes, and methods for forming a single crystal silicon ingot with use of such tubes. The composite polycrystalline silicon feed tubes include quartz and at least one dopant. The composite polycrystalline silicon feed tube may be made by a slip cast method.

Provided is an aluminum nitride structure that includes a plurality of aluminum nitride particles, wherein aluminum nitride particles that are adjacent are bound to each other through a boehmite phase containing boehmite, and the porosity is 30% or less. Also provided is a method for producing an aluminum nitride structure that includes: obtaining a mixture by mixing an aluminum nitride powder with a solvent containing water; and pressurizing and heating the mixture under conditions of a pressure of 10 to 600 MPa and a temperature of 50 to 300° C.

A method for forming a complex shape three-dimensional ceramic article by printing a first layer of a first material having a first fraction of first ceramic particles and a first fraction of a first polymeric ceramic precursor. A second layer is printed such that it is at least partially disposed on the first layer of a second material having a second fraction of second ceramic particles and a second fraction of a second polymeric ceramic precursor. A composite of the first layer and the second layer is heated at a temperature sufficient to decompose the first and second polymeric ceramic precursors and sinter the article. During the sintering process, the first and second layers with different fractions of ceramic particles undergo different degrees of shrinkage, resulting in a tuneable mismatch of the bilayer structure and accurately achieving a targeted geometry.

Compositions comprising preceramic resins and fumed alumina are described. The compositions can also include fillers, such as silicon carbide whiskers or zirconium diboride particles. The compositions can be used as three-dimensional printable inks for preparing ceramic composites, e.g., composites having complex geometry. Inclusion of fumed alumina as a rheology modifier in the composition can provide improved printing properties for the inks compared to preceramic resin inks that do not include fumed alumina.

Embodiments of disclosure may provide a method for forming an aluminum-containing nitride ceramic matrix composite, comprising heating a green body, an aluminum-containing composition, ammonia and a mineralizer composition in a sealable container to a temperature between about 400 degrees Celsius and about 800 degrees Celsius and a pressure between about 10 MPa and about 1000 MPa, to form an aluminum-containing nitride ceramic matrix composite characterized by a phosphor-to-aluminum nitride (AlN) ratio, by volume, between about 1% and about 99%, by a porosity between about 1% and about 50%, and by a thermal conductivity between about 1 watt per meter-Kelvin and about 320 watts per meter-Kelvin. The green body comprises a phosphor powder comprising at least one phosphor composition, wherein the phosphor powder particles are characterized by a D50 diameter between about 100 nanometers and about 500 micrometers, and the green body has a porosity between about 10% and about 80%. The aluminum-containing composition has a purity, on a metals basis, between about 90% and about 99.9999%. The fraction of free volume within the sealable container contains between about 10% and about 95% of liquid ammonia prior to heating the green body, the aluminum-containing composition, ammonia and the mineralizer composition in the sealable container.

A cBN sinter comprising cubic boron nitride grains and a binder phase, the binder phase comprising Ti.sub.2CN and Co.sub.2B, wherein the ratio I.sub.Ti2CN/I.sub.Co2B of a peak intensity I.sub.Ti2CN assigned to Ti.sub.2CN appearing at 2θ = 41.9° to 42.2° to a peak intensity I.sub.TiAl3 assigned to Co.sub.2B appearing at 2θ = 45.7° to 45.9° is in a range of 0.5 and 2.0 in an XRD measurement.

The present disclosure relates to a mold for glass forming, wherein the mold comprises a ceramic material, and wherein the ceramic material comprises aluminum nitride and hexagonal boron nitride, and wherein the ceramic material comprises from 50 to 80% by weight of aluminum nitride and from 20 to 50% by weight of hexagonal boron nitride, based on the total weight of the ceramic material. The present disclosure further relates to a process for using such molds to form curved glass plates.

Polycrystalline cubic boron nitride compact include a body having sintered microcrystalline cubic boron nitride in a matrix of binder material. The microcrystalline cubic boron nitride particles have a size ranging from 2 microns to 50 microns. The particles of microcrystalline cubic boron nitride include a plurality of sub-grains, each sub-grain having a size ranging from 0.1 micron to 2 microns. The compacts are manufactured in a high pressure—high temperature (HPHT) sintering process. The compacts exhibit intergranular defect formation following introduction of wear. The sub-grains promote crack propagation based on micro-chipping rather than on a cleavage mechanism and, in sintered bodies, cracks propagate intergranularly rather than intragranularly, resulting in increased toughness and improved wear characteristics as compared to monocrystalline cubic boron nitride. The compacts are suitable for use as abrasive tools.

An aluminum nitride-based sintered compact includes: aluminum nitride crystal particles containing Mg; composite oxide containing a rare earth element and Al, the composite oxide having a garnet crystal structure; and composite oxynitride containing Mg and Al. Particles of the composite oxide and particles of the composite oxynitride are interspersed between the aluminum nitride crystal particles. The composite oxide may include Y. A content of Mg in the aluminum nitride crystal particles may fall in a range of 0.1 mol % or more and 1.0 mol % or less, based on a total of all metal elements contained in the aluminum nitride crystal particles taken as 100 mol %. A semiconductor holding device includes the aluminum nitride-based sintered compact; and an electrostatic adsorptive electrode.