The present invention relates to parts of transparent corundum ceramics and the production and use of said parts.

A bonded abrasive article includes elongate shaped abrasive particles. The elongate shaped abrasive particles comprise an elongate shaped ceramic body having opposed first and second ends joined to each other by at least two longitudinal sidewalls. At least one of the at least two longitudinal sidewalls is concave along its length. At least one of the first and second ends is a fractured surface.

Nano-porous corundum ceramics and methods of manufacture are disclosed. The method of forming nano-porous corundum ceramics includes milling corundum powder in aqueous slurry with beads. The method further includes processing the slurry by a liquid shaping process to form a gelled body. The method further includes sintering the gelled body between 600° C. to 1000° C.

A method for forming rod-shaped particles includes reducing a length of rods derived from a slurry made up of particles and a reactant, wherein the rods are in a stabilized state in which the reactant has been at least partially reacted with a coagulant, but the rods have not been sintered, and subsequently sintering the reduced length stabilized rods. The reducing the length of the stabilized rods includes subjecting the stabilized rods to mechanical vibration applied by a device, or feeding the stabilized rods through a device having a rotating cutting mechanism.

Various shaped abrasive particles are disclosed. Each shaped abrasive particle includes a body having at least one major surface and a side surface extending from the major surface.

A wavelength converter is provided with a light-transmitting substrate and with a thin film that is formed on a surface of the light-transmitting substrate and that contains a phosphor. A sintered body that constitutes the light-transmitting substrate has an average particle size of 5-40 μm. The light-transmitting substrate contains at least 10-500 ppm by mass of MgO. The principal component of the phosphor is an α-sialon that is indicated by the general formula (Ca.sub.α,Eu.sub.β) (Si,Al).sub.12(O,N).sub.16 (provided that 1.5<α+β<2.2, 0<β<0.2, and O/N≦0.04).

An elongate shaped abrasive particle comprises an elongate shaped ceramic body having opposed first and second ends joined to each other by at least two longitudinal sidewalls. At least one of the at least two longitudinal sidewalls is concave along its length. At least one of the first and second ends is a fractured surface. Methods of making elongate shaped abrasive particles and abrasive articles including them are also disclosed.

A second mold is placed on a planar surface of a first mold to form a first mold cavity, which is filled with a first material slurry containing a first material powder and the molded slurry is caused to set, thereby forming a first molded part on the planar surface of the first mold. A third mold is placed on the planar surface of the first mold from which the second mold is removed and on which the first molded part is formed, thereby forming a second mold cavity. The second mold cavity is filled with a second material slurry which contains a second material powder different from the first material powder so as to mold the slurry in contact with the first molded part. The molded slurry is caused to set, thereby forming a second molded part on the planar surface of the first mold.

A method of forming a porous sol gel, including a dried porous sol gel, is provided comprising forming a sol gel from a sol gel-forming composition comprising a silane solution and a catalyst solution; and non-supercritically drying the sol gel to provide a dried porous sol gel having no springback. The dried porous sol gel can include dried macroporous or mesoporous sol gels or dried hybrid aerogels. The materials may contain open or filled pores. Such materials are useful as thermal insulators.

A ceramic heater includes: a ceramic plate which is provided with a wafer placement surface on an upper surface and in which a heating resistor is internally embedded; a ceramic tubular shaft with an upper end bonded to a lower surface of the plate; and power feeding members which penetrate a peripheral wall part of the tubular shaft in a vertical direction, and are electrically connected to the heating resistor. The power feeding members are embedded in the peripheral wall part of the tubular shaft, and are in tight contact with a ceramic material of the tubular shaft.