The present disclosure provides a boron carbide composite material having a novel composition with excellent mechanical properties, and a production method therefor. The boron carbide composite material has high fracture toughness and may be applied as a lightweight bulletproof ceramic material. The boron carbide composite material is a boron carbide/silicon carbide/titanium boride/graphite (B.sub.4C—SiC—TiB.sub.2—C) composite material. The composite material may overcome a technical limitation on increasing the fracture toughness of the boron carbide composite material, and may be produced as a high-density boron carbide composite material using a reactive hot-pressing sintering process at a relatively low temperature. The boron carbide composite material having excellent mechanical properties may be applied to general industrial wear-resistant parts and nuclear-power-related industrial parts, and particularly, may be actively used as a lightweight bulletproof material for personal use and for military aircraft including helicopters.

Disclosed is a method for fabricating a solid article from a boron carbide powder comprising boron carbide particles that are coated with a titanium compound. Further disclosed herein are the unique advantages of the combined use of titanium and graphite additives in the form of water soluble species to improve intimacy of mixing in the green state. The carbon facilitates sintering, whose concentration is then attenuated in the process of forming very hard, finely dispersed TiB2 phases. The further recognition of the merits of a narrow particle size distribution B4C powder and the use of sintering soak temperatures at the threshold of close porosity which achieve post-HIPed microstructures with average grain sizes approaching the original median particle size. The combination of interdependent factors has led to B.sub.4C-based articles of higher hardness than previously reported.

The invention relates to a copper/ceramic composite comprising—a ceramic substrate which contains aluminum oxide, —a coating which lies on the ceramic substrate and which is made of copper or a copper alloy, wherein the copper or the copper alloy has a particle size number distribution with a median value d.sub.50, an arithmetic mean value d.sub.arith, and a symmetry value S(Cu)=d.sub.50/d.sub.arith; the aluminum oxide has a particle size number distribution with a median value d.sub.50, an arithmetic mean value d.sub.arith, and a symmetry value S(Al.sub.2O.sub.3)=d.sub.50/d.sub.arith; and S(Al.sub.2O.sub.3) and S(Cu) satisfy the following condition: 0.7≤S(Al.sub.2O.sub.3)/S(Cu)≤1.4.

A method for producing a refractory lining in a combustion chamber operating in a reducing atmosphere. The lining includes at least one or more Zirconia (Zr)-based refractory lining members comprising one or more Zr-based parts. The Zr-based parts comprise at least 90 wt. %, preferably at least 95 wt. %, of monoclinic ZrO.sub.2 and/or partially stabilized ZrO.sub.2 and/or fully stabilized ZrO.sub.2, wherein the total content of tetragonal and cubic ZrO.sub.2 amounts to at least 20 wt. %, preferably more than 35 wt. %, as well as Zr based refractory lining members and methods for manufacturing the Zr based refractory lining members.

The invention relates to a copper-ceramic composite comprising: a ceramic substrate; and a copper or copper alloy coating on the ceramic substrate, the copper or copper alloy having grain sizes of 10 μm to 300 μm.

A substrate for mounting a light-emitting element according to the present disclosure contains a crystal particle of aluminum oxide and is composed of an alumina-based ceramic that contains 97% by mass or more of Al as a value of an Al.sub.2O.sub.3 equivalent among 100% by mass of all components thereof. An average value of an equivalent circle diameter of the crystal particle is 1.1 μm or greater and 1.8 μm or less and a standard deviation of an equivalent circle diameter thereof is 0.6 μm or greater and 1.4 μm or less.

Provided is a dielectric ceramic composition including a first component and a second component, wherein the first component comprises an oxide of Ca of 0.00 mol % to 35.85 mol % an oxide of Sr of 0.00 mol % to 47.12 mol %, an oxide of Ba of 0.00 mol % to 51.22 mol %, an oxide of Ti of 0.00 mol % to 17.36 mol %, an oxide of Zr of 0.00 mol % to 17.36 mol %, an oxide of Sn of 0.00 mol % to 2.60 mol %, an oxide of Nb of 0.00 mol % to 35.32 mol %, an oxide of Ta of 0.00 mol % to 35.32 mol %, and an oxide of V of 0.00 mol % to 2.65 mol %, and the second component includes at least (a) an oxide of Mn of 0.005% by mass to 3.500% by mass and (b) an oxide of Cu and/or an oxide of Ru.

In a first step of a method for producing a transparent AlN sintered body, first, a formed body is prepared by forming a mixture obtained by mixing a sintering aid with an AlN raw-material powder containing a plate-like AlN powder whose plate surface is a c-plane and which has an aspect ratio of 3 or more. At this time, the mixture is formed such that the plate surface of the plate-like AlN powder is disposed along a surface of the formed body. In a second step, an oriented AlN sintered body is obtained by subjecting the formed body to hot-press sintering in a non-oxidizing atmosphere while applying a pressure to the surface of the formed body. In a third step, a transparent AlN sintered body is obtained by sintering the oriented AlN sintered body at normal pressure in a non-oxidizing atmosphere to remove a component derived from the sintering aid.

Provided are a zirconia sintered body capable of being widely used as a dental material, in particular, a zirconia sintered body capable of being applied to both a dental material for a back tooth and a dental material for a front tooth and a simple and easy method for manufacturing the zirconia sintered body. The method for manufacturing a zirconia sintered body includes a molding step of molding a powder composition that has an yttria content of more than 3% by mole and 5.2% by mole or less and that contains a first zirconia powder having an yttria content of 2% by mole or more and 4% by mole or less and a second zirconia powder having an yttria content of more than 4% by mole and 6% by mole or less to obtain a green body, and a sintering step of sintering the green body to obtain a sintered body.

A chamber component for a processing chamber comprises a ceramic body consisting of a sintered ceramic material consisting essentially of one or more phase of Y.sub.2O.sub.3—ZrO.sub.2. The ceramic material consists essentially of 55-65 mol % Y.sub.2O.sub.3 and 35-45 mol % ZrO.sub.2.