A silicon nitride powder for sintering which, despite of its fine powdery form, shows a very small increase in the oxygen concentration with time and features excellent storage stability. The silicon nitride powder for sintering has a specific surface area of 5 to 30 m.sup.2/g, and is characterized by having a hydrophobicity (M value) of 30 or more and an increase in the oxygen concentration of 0.30% by mass or less after left to stand in the air of a humidity of 90% and 20° C. for 48 hours. The silicon nitride powder for sintering can be obtained by dry-pulverizing aggregated masses of the silicon nitride in an inert atmosphere in the presence of a silane coupling agent.

A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 μm, (c) (i) a cumulative pore volume in a pore diameter range of 20 μm or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 μm and 50 μm or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 μm being 12% or more of the total pore volume.

Embodiments are directed to the field of ceramics and relate to electron-emitting ceramics such as those which can be used as cathode material for electron emissions in space flight systems, for example. Embodiments specify an electron-emitting ceramic which has an improved temperature conductivity with a simultaneously continuous electron emission. The electron-emitting ceramic contains at least>70 vol. % C12A7 electride and a proportion of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, In, Sn, Sb, Te, Tl, Pb, or Bi as metal and/or with Ti, wherein the proportion of the metals lies between>0 and<30 vol. %, and the ceramic has a density of at least 85% of the theoretical density of the ceramic and the ceramic contains 0 to maximally 10 vol. % production-specific impurities.

An example article may include a component, a substrate including a first ceramic, a joining layer between the component and the substrate, and a joint surface coating between the substrate and the joining layer. The joint surface coating may include a diffusion barrier layer including a second ceramic material, and a compliance layer including at least one of a metal or a metalloid. An example technique may include holding a first joining surface of a coated component adjacent a second joining surface of a second component. The example technique may further include heating at least one of the coated component, the second component, and a braze material, and brazing the coated component by allowing the braze material to flow in a region between the first joining surface and the second joining surface.

Provided is an inorganic structure including a plurality of magnesium oxide particles; and a binding part that covers a surface of each of the magnesium oxide particles and binds the magnesium oxide particles together. The binding part contains an amorphous compound containing silicon, a metallic element other than silicon, and oxygen, and contains substantially no alkali metal, B, V, Te, P, Bi, Pb, and Zn. Also provided is a method for producing an inorganic structure including: a step for obtaining a mixture by mixing a plurality of magnesium oxide particles, a plurality of amorphous silicon dioxide particles, and an aqueous solution containing a metallic element other than silicon; and a step for pressurizing and heating the mixture under conditions of a pressure of 10 to 600 MPa and a temperature of 50 to 300° C.

A hybrid sandwich ceramic matrix composite (CMC) may comprise a first facesheet, a second facesheet, and a core between and bonded to both of the first facesheet and the second facesheet. The first facesheet and the second facesheet may each include filaments in a ceramic matrix. The hybrid sandwich CMC may be configured for exposure to a thermal gradient in which the first facesheet is exposed to a higher temperature environment than the second facesheet. The first facesheet and the second facesheet may have at least closely matching coefficients of thermal expansion, and the first facesheet may have a higher compressive strength than the second facesheet.

Disclosed is a method of manufacturing a ceramic powder, which includes forming a slurry by mixing of first ceramic particles, binder and water, spraying and drying the slurry to form a first ceramic core portion, and thermally treating and shaping the first ceramic core portion. The first ceramic core portion has a first flexural strength and a first coefficient of thermal expansion. The method further includes forming another slurry to form a second ceramic shell portion formed by second ceramic particles and covering the first ceramic core portion. The second ceramic shell portion has a second flexural strength and a second coefficient of thermal expansion. The ceramic powder is formed by thermally treating and shaping the first ceramic core portion and the second ceramic shell portion.

Disclosed herein are methods for preparing a titanate compound powder comprising titanate compound particles having a controlled particle size and/or particle size distribution. The methods include mixing at least one first inorganic compound chosen from sources of a first metal or metal oxide, at least one second inorganic compound chosen from sources of titania, and at least one binder to form a mixture; calcining the mixture to form a polycrystalline material comprising a plurality of titanate compound grains and a plurality of micro-cracks; and breaking the polycrystalline material along at least a portion of the microcracks. Also disclosed are titanate compound powders having a controlled particle size distribution, ceramic batch compositions comprising the powders, and ceramic articles prepared from the batch compositions.

Provided is a thermoelectric material satisfying (MX).sub.1+a(TX.sub.2).sub.n and having a superlattice structure, wherein M is at least one element selected from the group consisting of Group 13, Group 14, and Group 15, T is at least one element selected from Group 5, X is a chalcogenide element, a is a real number satisfying 0<a<1, and n is a natural number of 1 to 3.

cubic boron nitride sintered material including 90.0% by mass or more and 99.5% by mass or less of cubic boron nitride and 0.5% by mass or more and 10.0% by mass or less of silicon, wherein the cubic boron nitride sintered material has a total content of the cubic boron nitride and the silicon of 94.0% by mass or more and 100% by mass or less.