Provided is a silicon-carbide-sintered body in which plural crystal grains including silicon carbide are densely formed so as to be adjacent to each other. Sc and Y elements are present in a rich phase at a triple point at which interfaces of the crystal grains forming the sintered body meet each other without solid-solution of the elements in the crystal grains. Accordingly, sintering is feasible at a temperature of 1950 C. or lower, and an EB layer including a rare-earth-Si oxide containing the Sc and Y elements is formed on a surface thereof without an EB coating process, and is also formed up to the inner region of a silicon carbide base, resulting in strong three-dimensional bonding, so that the possibility of peeling of the EB layer is reduced and a new EB layer is formed even when peeling occurs, increasing the resistance to corrosion of the silicon carbide material.

A silicon carbide porous body includes: (A) silicon carbide particles as an aggregate; and (B) at least one selected from the group consisting of metallic silicon, alumina, silica, mullite and cordierite. The silicon carbide porous body has amorphous and/or crystalline SiO.sub.2 or SiO on a surface(s) of the component (A) and/or the component (B). The silicon carbide porous body contains 6% by mass or less of -cristobalite in the amorphous and/or crystalline SiO.sub.2 or SiO.

A porous material includes aggregate particles and a binding material. In the aggregate particles, oxide films containing cristobalite are provided on surfaces of particle bodies that are silicon carbide particles or silicon nitride particles. The binding material binds the aggregate particles together in a state where pores are provided therein. The porous material contains at least one of copper, calcium, and nickel as an ancillary component.

A silicon carbide-natured refractory block includes a fire-resistant block body, and a calcination coated layer.

The fire-resistant block body includes a silicon carbide-natured refractory having a predetermined configuration. The calcination coated layer includes silicon oxide made by heating an outer superficial portion of the fire-resistant block body to oxidize at least some of silicon carbide therein to turn the silicon carbide into the silicon oxide. The silicon oxide sinters the calcination coated layer to increase the corrosion resistance.

Coated components, along with methods of their formation, are provided. The coated component may include a ceramic substrate having a Si-treated layer surrounding a ceramic core and an environmental barrier coating on the Si-treated layer of the ceramic substrate. The ceramic core may include silicon carbide, and the Si-treated layer may be pretreated to tailor its surface's properties for inhibiting or delaying the formation of carbon oxides to upon exposure of the Si-treated layer to oxygen.

A long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with an ultra-high melting point is prepared as follows: preparing the HfC powder and the HfN powder according to a mass ratio of HfC:HfN=(1-7):1; uniformly mixing the HfC powder and the HfN powder with the carbon powder and the carbon nitride powder to obtain a mixed powder, wherein the amount of the carbon powder and the amount of the carbon nitride powder do not exceed 8.0 wt. % and 5.0 wt. %, respectively, of the mixed powder mass; and performing spark plasma sintering on the mixed powder to produce the ceramic with the ultra-high melting point, a density ?98%, and a uniform C/N content distribution. The ultra-high temperature ceramic is suitable for ultra-high temperature ablation-resistant protection at ?3000? C. The ceramic maintains a close to zero ablation rate and a continuously stable oxidation-resistant protective structure after ablation for 300 s.

An article including carbon-carbon composite substrate may be treated with an antioxidant coating prior to use in an oxidizing environment. The antioxidant coating may be configured to reduce oxidation at an external surface of the CC composition and reduce ingress of oxidants into pores or other open passages defined by the CC composite substrate to avoid internal oxidation. An example article includes a CC composite substrate, a bond coat, and an antioxidant coating. The CC composite substrate defines a friction surface and a non-friction surface. The bond coat is disposed on the non-friction surface. The antioxidant coating may be disposed on at least a portion of the bond coat. The antioxidant coating may include ytterbium disilicate and a sintering aid.

A part made of composite material includes fiber reinforcement including silicon carbide fibers presenting an oxygen content less than or equal to 1% in atomic percentage; and a matrix present in the pores of the fiber reinforcement and including at least one sintered silicate phase including at least one rare earth silicate, mullite, or a mixture of mullite and of at least one rare earth silicate, the matrix including at least a first phase including mullite and a second phase, different from the first phase, including at least one rare earth silicate.

Disclosed herein are compounds, methods, and tools which comprise tungsten borides and mixed transition metal borides.

Provided are a corrosion-resistant member and an electrostatic chuck device using the same, in which corrosion resistance to halogen corrosive gas such as fluorine corrosive gas or chlorine corrosive gas and plasma thereof is high, dielectric constant and volume resistivity are high, and dielectric loss is low. The corrosion-resistant member is formed of a composite oxide sintered compact containing aluminum, samarium, and a rare earth metal element other than samarium, in which the rare earth metal element other than samarium has an ionic radius of 0.8810.sup.10 m or more.