An alumina powder containing: a first alumina particle having average particle diameter from 0.1 μm to 1 μm; a second alumina particle having average particle diameter from 1 μm to 10 μm; and a third alumina particle having average particle diameter from 10 μm to 100 μm, wherein the particle diameters are measured using laser light diffraction scattering particle size distribution analyzer, average sphericity of first alumina particle having projected area equivalent circle diameter from 0.1 μm to 1 μm as determined by microscopy is from 0.80 to 0.98, and a ratio of D90/D10 of first alumina particle is from 2.0 to 8.0 wherein the ratio of D90/D10 is a ratio when particle diameter at cumulative value of 10% from fine particle side of cumulative particle size distribution on volume basis is D10 and particle diameter at cumulative value of 90% from fine particle side is D90.

The alumina powder contains: a first alumina particle having an average particle diameter of 0.1 .Math.m or more and less than 1 .Math.m; a second alumina particle having an average particle diameter of 1 .Math.m or more and less than 10 .Math.m; and a third alumina particle having an average particle diameter of 10 .Math.m or more and 100 .Math.m or less, wherein each of the average particle diameters is a particle diameter measured using laser light diffraction scattering particle size distribution analyzer, average sphericity of first alumina particle having projected area equivalent circle diameter of 0.1 .Math.m or more and 1 .Math.m or less as determined by microscopy is 0.80 or more and 0.98 or less, a specific surface area of first alumina particle is 1.9 m.sup.2/g or more and 20.0 m.sup.2/g or less, and content ratio of an α crystal phase is 80% by mass or more.

The present invention relates to a calcined shaped alumina and to a method of preparing a calcined shaped alumina. The method comprises that the alumina in the alumina suspension is hydrothermally aged to have a specific crystallite size. This in turn produces a highly stable alumina in the form of a calcined shaped alumina particularly at temperatures of 1200° C. and above.

A particulate material having a body including a dopant contained in the body, the dopant is non-homogenously distributed throughout the body and the body has a maximum normalized dopant content difference of at least 35%.

A particulate material having a body including a dopant contained in the body, the dopant is non-homogenously distributed throughout the body and the body has a maximum normalized dopant content difference of at least 35%.

A composition having a plurality of abrasive particles including alumina, the plurality of abrasive particles have mesoporosity with an average meso branching index of at least 55 junctions/microns.sup.2 and a median particle size (D50) of at least 5 microns.

A process of forming a sintered article includes heating a green portion of a tape of polycrystalline ceramic and/or minerals in organic binder at a binder removal zone to a temperature sufficient to pyrolyze the binder; horizontally conveying the portion of tape with organic binder removed from the binder removal zone to a sintering zone; and sintering polycrystalline ceramic and/or minerals of the portion of tape at the sintering zone, wherein the tape simultaneously extends through the removal and sintering zones.

A process of forming a sintered article includes heating a green portion of a tape of polycrystalline ceramic and/or minerals in organic binder at a binder removal zone to a temperature sufficient to pyrolyze the binder; horizontally conveying the portion of tape with organic binder removed from the binder removal zone to a sintering zone; and sintering polycrystalline ceramic and/or minerals of the portion of tape at the sintering zone, wherein the tape simultaneously extends through the removal and sintering zones.

An abrasive particle having a body including a first major surface, a second major surface opposite the first major surface, and a side surface extending between the first major surface and the second major surface, such that a majority of the side surface comprises a plurality of microridges.

A pseudo-boehmite has a dry basis content of 55-85 wt % and contains a phosphoric acid ester group. The sodium oxide content is not greater than 0.5 wt %, and the phosphorus content (in terms of phosphorus pentoxide) is 1.2-5.7 wt %, relative to 100 wt % of the total weight of the pseudo-boehmite. The pseudo-boehmite has a low sodium content.