Disclosed is a ceramic sintered body comprising magnesium aluminate spinel of composition MgAl.sub.2O.sub.4 having from 90 to 100% by volume of a cubic crystallographic structure and a density of from 3.47 to 3.58 g/cc, wherein the ceramic sintered body is free of sintering aids. A method of making the ceramic sintered body comprising spinel is also disclosed.

A composition which can be photopolymerized to make a part consisting of an oxide ceramic, or a hybrid part comprising at least one oxide ceramic and organic constituents, by a stereolithographic technique, the composition comprising: at least one photopolymerizable organic compound; at least one photo-initiator; at least one precursor of the oxide ceramic wherein the composition comprises from 25% to 70% by mass, relative to the total mass of the composition, of the at least one precursor of the oxide ceramic; and wherein the at least one precursor of the oxide ceramic comprises a mixture comprising a nanometric powder of the oxide ceramic, and at least one other element selected from a micrometric powder of the oxide ceramic and a pre-ceramic compound of the oxide ceramic.

A method of making a carbon-carbon composite may comprise forming a Silicon-Aluminum-Oxygen-Nitrogen (SiAlON) precursor suspension and infiltrating a fibrous preform with the SiAlON precursor suspension. A SiAlON forming heating treatment may be performed on the fibrous preform to form SiAlON particles. The fibrous preform may be densified using chemical vapor infiltration to form a densified fibrous preform.

A crack self-healing functionally gradient material for ceramic cutting tools and a preparation method thereof. The material for ceramic cutting tools has a symmetrical gradient structure, and based on the percentage by mass, components of each layer include 50%-80% of Ti(C.sub.7,N.sub.3), 25%-5% of (W.sub.7,Ti.sub.3)C and 20%-0% of TiSi.sub.2; contents of components of layers that are symmetrical relative to a central layer are the same and a thickness is symmetrically distributed; a content of Ti(C.sub.7,N.sub.3) gradually increases from the surface layer to the central layer, contents of (W.sub.7,Ti.sub.3)C and Ti Si.sub.2 gradually decrease by 5% from the surface layer to the central layer, and the contents of Ni and Mo gradually increase from the surface layer to the central layer.

A substrate for mounting a light-emitting element according to the present disclosure contains a crystal particle of aluminum oxide and is composed of an alumina-based ceramic that contains 97% by mass or more of Al as a value of an Al.sub.2O.sub.3 equivalent among 100% by mass of all components thereof. An average value of an equivalent circle diameter of the crystal particle is 1.1 μm or greater and 1.8 μm or less and a standard deviation of an equivalent circle diameter thereof is 0.6 μm or greater and 1.4 μm or less.

Provided is a lithium complex oxide sintered plate for use in a positive electrode of a lithium secondary battery. The lithium complex oxide sintered plate has a structure in which a plurality of primary grains having a layered rock-salt structure are bonded, and has a porosity of 3 to 40%, a mean pore diameter of 15 μm or less, an open porosity of 70% or more, and a thickness of 15 to 200 μm. The plurality of primary grains has a primary grain diameter, i.e., a mean diameter of the primary grains, of 20 μm or less and a mean tilt angle of more than 0° to 30° or less. The mean tilt angle is a mean value of the angles defined by the (003) planes of the primary grains and the plate face of the lithium complex oxide sintered plate.

A polycrystalline cubic boron nitride comprising 96% by volume or more of cubic boron nitride, wherein the cubic boron nitride has a dislocation density of 8×10.sup.15/m.sup.2 or less, the polycrystalline cubic boron nitride comprises a plurality of crystal grains, and the plurality of crystal grains have a median diameter d50 of an equivalent circle diameter of less than 100 nm.

A dielectric composition includes dielectric particles. At least one of the dielectric particles include a main phase and a secondary phase. The main phase has a main component of barium titanate. The secondary phase exists inside the main phase and has a higher barium content than the main phase.

The invention relates to a porous zirconia article in particular for use in the dental or orthodontic field, the porous zirconia article comprising ZrO.sub.2: 80 to 87 wt. %, Y.sub.2O.sub.3: 3 to 5 wt. %, Al.sub.2O.sub.3: 10 to 14 wt. %, wt. % with respect to the weight of the porous zirconia article, the porous zirconia article being characterized by a BET surface from 15 to 100 m.sup.2/g. The invention also relates to a sintered zirconia article in particular for use in the dental or orthodontic field, the sintered zirconia article comprising ZrO.sub.2: 80 to 87 wt. %, Y.sub.2O.sub.3: 3 to 5 wt. %, Al.sub.2O.sub.3: 10 to 14 wt. %, wt. % with respect to the weight of the porous zirconia article, the sintered zirconia article being characterized by a corundum crystal phase content of 7 to 12 wt. % and a flexural strength of at least 2,000 MPa.

The present invention relates to sintered platelet-like randomly shaped abrasive particles based on alpha alumina having a hardness H.sub.V of at least 20 GPa and a crystal structure with an average crystal size between 100 nm and 300 nm, whereby the abrasive particles comprise a body having a first surface and a second surface opposite to the first surface, both surfaces are separated from each other by a randomly shaped sidewall having a thickness (T) between 20 μm and 500 μm.