The present invention relates to a ceramic, to a process for preparing the ceramic and to the use of the ceramic as a dielectric in a capacitor.

A grain-grade zirconia toughened alumina ceramic substrate and a method for preparing the same. The ceramic substrate is prepared from alumina power (main phase) and zirconia powder (secondary phase) in a binary azeotrope of anhydrous ethanol and butanone in the presence of magnesia-alumina spinel powder (as sintering aid), phosphate ester (as dispersant), polyvinyl butyral (as binder) and dibutyl phthalate (as plasticizer). In a mixture of the alumina power and the zirconia powder, a volume percentage of the alumina power is 82.44-96.7%, and a volume percentage of the zirconia powder is 3.30-17.56%. The magnesia-alumina spinel powder is 0.1-4.0% by weight of the mixture of the alumina power and the zirconia powder. A particle size ratio of the alumina powder to the zirconia powder is 2.415-4.444.

A disclosure is provided for methods to prepare high-strength and high-toughness partially stabilized zirconia (PSZ) materials by incorporating a starting ceramic powder in which the stabilizing oxide agent is pre-alloyed with the zirconia material powder. The ceramic powder is pre-stabilized so there is little or no remaining free stabilizing oxide, thereby resulting in an improved material that is more convenient to process using conventional ceramic processing techniques.

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.

A zirconia ceramic includes the following elements: 60.5-70.5 wt % of Zr, 2.5-5.45 wt % of Y, 0.05-2.65 wt % of Al, 0.015-1.07 wt % of Si, and 0.34-2.8 wt % of M. M includes at least one of Nb or Ta. The zirconia ceramic has a phase composition which includes tetragonal zirconia, alumina and zirconium silicate. The total content of alumina and zirconium silicate is 0.2-12 wt %, and the content of the tetragonal zirconia is 84-99.3 wt %. The tetragonal zirconia includes a solid solution of zirconia formed with yttrium oxide and M.sub.xO.sub.y, x satisfies 1≤x≤3, and y satisfies 3≤y≤6.

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.

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 zirconia sintered body is provided and includes yttria and zirconia, containing yttria by a content ranging from 4.5 mol % or more to 6.5 mol % or less and zirconia as the remainder, the total light transmittance of a 1-mm thick sample measured in compliance with JIS K 7361-1 being 46.5% or higher, the three-point bending strength being 700 MPa or higher, and a ratio of an integrated value for the total light transmittance to an integrated value for the parallel light transmittance of a 1-mm thick sample measured at the measurement wavelength ranging from 400 to 700 nm being 1.3% or less.

The disclosure relates to sintered ceramic grains comprising 3-55 wt. % alumina, 40-95 wt. % zirconia and 1-30 wt. % of one or more other inorganic components. The invention further relates to a method for preparing ceramic grains according to the invention, comprising: making a slurry comprising alumina, zirconia; making droplets of the slurry; introducing the droplets in a liquid gelling-reaction medium wherein the droplets are gellified; drying the gellified deformed droplets.

The invention relates to a blank of a ceramic material, wherein a first ceramic material and then a second ceramic material of different compositions are filled into a die and wherein the materials are pressed and after pressing are sintered. A layer of the first ceramic material is thereby filled into the die and a first cavity formed in the layer, the second ceramic material is then filled into the first open cavity and the materials pressed together and then heat-treated.