A dielectric composition is provided. The dielectric composition includes: a main component made of: a first complex oxide expressed by a chemical formula {K(Ba.sub.1-xSr.sub.x).sub.2Nb.sub.5O.sub.15}; and a second complex oxide expressed by a chemical formula that differs the chemical formula of the first complex oxide. The second complex oxide is a complex oxide expressed by one of chemical formulae: {(Ca.sub.1-ySr.sub.y)(Zr.sub.1-zTi.sub.z)O.sub.3}; {Ba(Ti.sub.1-uZr.sub.u)O.sub.3}; {(Ca.sub.1-vSr.sub.v)TiSiO.sub.5}; and {(Ba.sub.1-wRe.sub.2w/3)Nb.sub.2O.sub.6}, x satisfies 0.35≦x≦0.75, and a satisfies 0.25≦a≦0.75 when a molar ratio between the first and second complex oxides is defined by a:b in an order and a+b=1.00.

An alumina sintered body having a low dielectric loss tangent and a method for manufacturing the alumina sintered body are provided. An alumina sintered body contains Al.sub.2O.sub.3 99.50 mass % or more, and 99.95 mass % or less and sodium and silicon, wherein at a surface layer A in any given cross-section and a central portion B of the cross-section in a depth direction from the surface layer A, a concentration ratio of sodium to silicon in the surface layer A is smaller than the concentration ratio of sodium to silicon at the central portion B.

Disclosed is a method of manufacturing a ceramic powder, which includes forming a slurry by mixing of first ceramic particles, binder and water, spraying and drying the slurry to form a first ceramic core portion, and thermally treating and shaping the first ceramic core portion. The first ceramic core portion has a first flexural strength and a first coefficient of thermal expansion. The method further includes forming another slurry to form a second ceramic shell portion formed by second ceramic particles and covering the first ceramic core portion. The second ceramic shell portion has a second flexural strength and a second coefficient of thermal expansion. The ceramic powder is formed by thermally treating and shaping the first ceramic core portion and the second ceramic shell portion.

A ZrO.sub.2—Al.sub.2O.sub.3-based ceramic sintered compact containing tetragonal ZrO.sub.2 particles having a crystallite size of from 5 to 20 nm as a main component and having an α-Al.sub.2O.sub.3 crystallite size of not greater than 75 nm and a relative density of not less than 99% can be produced by preparing a Y.sub.2O.sub.3 partially stabilized ZrO.sub.2—Al.sub.2O.sub.3-based powder having a molar ratio (mol %) of zirconia (ZrO.sub.2) and yttria (Y.sub.2O.sub.3) of from 96.5:3.5 to 97.5:2.5 and a mass ratio (mass %) of ZrO.sub.2 containing Y.sub.2O.sub.3 and alumina (Al.sub.2O.sub.3) of from 85:15 to 75:25, molding this powder by cold isostatic pressing, and then performing sintering to a high density by microwave sintering for 45 to 90 min in an inert gas atmosphere at 1200 to 1400° C. When performing microwave sintering, a heating rate is preferably from 5 to 20° C./min up to 600° C. and from 50 to 150° C./min at 600° C. or higher.

A method of forming a super hard polycrystalline construction comprises forming a liquid suspension of nano-sized super hard particles and particles of super hard material having an average particle or grain size of 1 or more microns, dispersing the particles in the liquid suspension to form a substantially homogeneous suspension which is then dried and sintered to form a body of polycrystalline super hard material comprising a first and second fractions of super hard grains, the nano-sized particles forming the second fraction. The super hard grains in the first fraction are bonded along at least a portion of the peripheral surface(s) thereof to at least a portion of a plurality of nano-sized grains in the second fraction, the grains in the first fraction having a greater average grain size than that of the grains in the second fraction which is less than 999 nm, the average grain size of the first fraction being around 1 micron or more

A method of forming a ceramic matrix composite includes depositing particles on a ceramic fabric formed from a plurality of ceramic tows, applying a binder to at least the particles to form a stabilized ceramic fabric, forming a preform using the stabilized ceramic fabric, and densifying the preform. The ceramic tows are formed from a first material and the particles are formed from at least a second material.

A method of forming a ceramic matrix composite includes applying a binder comprising water and 5% to 15% polyvinyl alcohol to a ceramic material and decomposing the binder to leave behind a discontinuous carbon layer within the ceramic material. The step of applying the binder includes one of a spraying, pipetting, painting, immersing, and pre-pregging technique.

A method of preparing a ceramic fabric for use in a ceramic matrix composite includes arranging a plurality of tows to form a ceramic fabric with a first inter-tow spacing, applying a binder material to the ceramic fabric, and applying pressure to the ceramic fabric to form a pressure stabilized ceramic fabric. Each of the plurality of tows of the ceramic fabric has a first thickness, and each of at least a subset of the plurality of tows of the pressure stabilized ceramic fabric has a second thickness less than the first thickness.

A composition suitable for 3D printing. The composition is in the form of a filament and includes: a) a metal and/or ceramic powder: b) an organic binding phase including two parts: b1) at least one thermoplastic compound selected from thermoplastic polymers and waxes; and b2) at least one volatile organic compound which has a vapor pressure at 50° C., ranging from more than 0 bar to 0.05 bar, wherein the amount of the at least one volatile organic compound ranges from more than 0.5% to 40% (v/v) by volume relative to the total volume of the composition.

A method for post-processing a colored zirconium oxide ceramic, the method comprising: putting the colored zirconium oxide ceramic along with a deoxidant into a heating device, conducting a firing process at a preset temperature, and a colorant containing Pr.sup.3+ is used for the coloring, and the deoxidant is excessive with respect to a stoichiometric amount of oxygen in the heating device. The technical solution can completely replace Pe.sup.3+ with Pr.sup.3+ to color the zirconium oxide ceramic yellow.