A ceramic contains, in mass percent: Si.sub.3N.sub.4: 20.0 to 60.0%, ZrO.sub.2: 25.0 to 70.0%, and one or more oxides selected from MgO, Y.sub.2O.sub.3, CeO.sub.2, CaO, HfO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, SiO.sub.2, MoO.sub.3, CrO, CoO, ZnO, Ga.sub.2O.sub.3, Ta.sub.2O.sub.5, NiO, and V.sub.2O.sub.5: 5.0 to 15.0%. The ceramic has a coefficient of thermal expansion as high as that of silicon and an excellent mechanical strength, allows fine machining with high precision, and prevents particles from being produced.

Provided is a boron nitride sintered body including boron nitride particles and pores, the boron nitride sintered body having a sheet shape and a thickness of less than 2 mm. Provided is a method for manufacturing a boron nitride sintered body, the method including a sintering step of molding and heating a blend containing a boron carbonitride powder and a sintering aid to obtain a sheet-shaped boron nitride sintered body including boron nitride particles and pores, in which a thickness of the boron nitride sintered body obtained in the sintering step is less than 2 mm.

Thermal barrier coatings consist of a tantala-zirconia mixture that is stabilized with two or more stabilizers. An exemplary thermal barrier coating consists of, by mole percent: about 8% to about 30% YO.sub.1.5; about 8% to about 30% YbO.sub.1.5 or GdO.sub.1.5 or combination thereof; about 8% to about 30% TaO.sub.2.5; about 0% to about 10% HfO.sub.2; and a balance of ZrO.sub.2.

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.

Disclosed herein are embodiments of low temperature co-fireable barium tungstate materials which can be used in combination with high dielectric materials, such as nickel zinc ferrite, to form composite structures, in particular for isolators and circulators for radiofrequency components. Embodiments of the material can include flux, such as bismuth vanadate, to reduce co-firing temperatures.

SiC matrix composite material, where heat-resistant long fiber such as carbon fiber is employed as a material for reinforcement and SiC is employed for the matrix, which significantly improves mechanical properties such as strength and toughness. The SiC matrix composite material, includes a SiC matrix and heat-resistant long fiber, wherein the SiC matrix includes both of alpha-type SiC and beta-type SiC, and the alpha-type SiC and the beta-type SiC are detected by micro-region X-ray diffraction with an X-ray beam diameter of no greater than 300 micrometers substantially at every region of every cross-section of the SiC matrix, the beta-type SiC has an average crystallite size that is no greater than 500 nm and greater than an average crystallite size of the alpha-type SiC, and the SiC matrix composite material has a porosity of no greater than 20% by volume.

A preform for making a component of a braking system having a fibre-reinforced ceramic composite material, obtained by forming and subsequent pyrolysis of a pre-preg is described. Also described is a component of a braking system made wholly or in part from the preform, and a method for making a preform in a fibre-reinforced ceramic composite material.

A heat-dissipating member includes aluminum oxide ceramics that includes crystal particles of aluminum oxide. The aluminum oxide ceramics includes 98 mass % or higher of aluminum in terms of Al.sub.2O.sub.3 with respect to 100 mass % of all constituents. The crystal particles have an average equivalent circle diameter of 1.6 μm or more and 2.4 μm or less. An equivalent circle diameter cumulative distribution curve of the crystal particles has a first diameter at 10 cumulative percent and a second diameter at 90 cumulative percent that is different from the first diameter by 2.1 μm or more and 4.2 μm or less.

A method for making ceramic composites via sintering a mixture of alumina and oil fly ash. The alumina is in the form of nanoparticles and/or microparticles. The oil fly ash may be treated with an acid prior to the sintering. The composite may comprise graphite carbon derived from oil fly ash dispersed in an alumina matrix. The density, mechanical performance (e.g. Vickers hardness, fracture toughness), and thermal properties (e.g. thermal expansion, thermal conductivity) of the ceramic composites prepared by the method are also specified.