A member for a plasma processing apparatus configured of a tubular body composed of a ceramic having a rare earth element oxide, aluminum oxide, or a rare earth element aluminum composite oxide as a main constituent and including a through hole in an axial direction, in which a number of recessed portions having a depth of from 10 μm to 20 μm, the depth starting from a ridge located between an inner peripheral surface of the tubular body and a target observation surface obtained by polishing from an outer peripheral surface of the tubular body toward an axis, is 2 or less per 1 mm of the ridge.

A method may produce a ceramic part with a mother-of-pearl effect, in particular for watchmaking. Such methods may include: forming a ceramic body; depositing a layer of an oxy-nitride component of the OxNy type on at least a portion of the ceramic body; and oxidizing at least a portion of the oxy-nitride layer, preferably by heating.

A refractory article including a body having central opening extending through at least a portion of the body, the central opening having a receiving surface having a convex curvature. In an embodiment, the body can include a coupling protrusion extending from a portion of an upper surface of the body and a coupling depression on a portion of a bottom surface of the body.

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.

A cubic boron nitride particle population having highly-etched surfaces and a high toughness index is produced by blending a reactive metal powder with a plurality of cubic boron nitride particles to form a blended mixture. The blended mixture is compressed to form a compressed mixture. The compressed mixture is subjected to a temperature and a pressure, where the temperature is controlled to cause etching of the plurality of cubic boron nitride particles by reaction of cubic boron nitride with the reactive metal powder, thereby forming a plurality of etched cubic boron nitride particles. Also, the temperature and pressure are controlled to cause boron nitride to remain in a cubic boron nitride phase. Afterwards, the plurality of etched cubic boron nitride particles is recovered from the compressed mixture to form the particle population. Preferably, the particle population contains no hexagonal boron nitride.

Disclosed herein is a dual density disc comprising a dense outer tube comprising a metal oxide having a purity of greater than 92%; and a porous core comprising a metal oxide of a lower density than a density of the dense outer tube; wherein the porous core has a metal oxide purity of greater than 99%; where the dense outer tube has an inner tapered surface.

A wafer boat according to the present disclosure includes a plurality of support columns, each having a pillar shape and comprising a plurality of grooves configured to have a wafer placed thereon, and support plates configured to support both end portions of the plurality of support columns, respectively. Each of the plurality of support columns are formed of a ceramic containing aluminum oxide or silicon carbide as a main constituent, and an outer side surface of the plurality of support columns is a ground surface and/or a polished surface.

A member for optical glass production apparatus is a member exposed to a gas containing a halogen element in a high temperature environment; the member includes a first member (4) directly or indirectly supporting an optical glass (10) and a second member (5) supporting the first member (4).

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.

A method for machining by laser ablation or by micro-milling a raised and/or hollow structure on an impression of an injection mould. A method for manufacturing a ceramic or cermet item by injection using the injection mould to produce an item, and in particular a watch bezel, decorated directly during the injection.