Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 μm, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

A method for achieving sintering of ceramics at room temperature is disclosed. The method includes steps of: providing ceramic green body; placing the ceramic green body into a sealed container containing water vapor to cause the ceramic green body to soak up the water vapor to obtain an aqueous ceramic green body; removing the aqueous ceramic green body from the sealed container, and connecting a power supply to the aqueous ceramic green body; applying a voltage to the aqueous ceramic green body; and increasing the voltage to a predetermined voltage value to cause a surface discharge or an internal discharge to occur on the aqueous ceramic green body, and stopping the power supply after a predetermined time, thereby obtaining a ceramic. A ceramic formed by the method is also disclosed.

A sintered body includes a crystal grain containing silicon nitride, and a grain boundary phase. If dielectric losses of the sintered body are measured while applying an alternating voltage to the sintered body and continuously changing a frequency of the alternating voltage from 50 Hz to 1 MHz, an average value ε.sub.A of dielectric losses of the sintered body in a frequency band from 800 kHz to 1 MHz and an average value ε.sub.B of dielectric losses of the sintered body in a frequency band from 100 Hz to 200 Hz satisfy an expression |ε.sub.A−ε.sub.B|≤0.1.

One aspect of the disclosure provides an optical wavelength conversion member including a polycrystalline ceramic sintered body containing, as main components, Al.sub.2O.sub.3 crystal grains and crystal grains represented by formula (Y,A).sub.3B.sub.5O.sub.12:Ce. In the optical wavelength conversion member, a (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain has a region wherein the A concentration of a peripheral portion of the (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain is higher than that of an interior portion of the (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain. Thus, the optical wavelength conversion member exhibits high fluorescence intensity (i.e., high emission intensity) and high heat resistance (i.e., low likelihood of temperature quenching). The optical wavelength conversion member has a structure wherein the element A concentration of a peripheral portion of a (Y,A).sub.3B.sub.5O.sub.12:Ce crystal grain differs from that in an interior portion of the crystal grain. This structure can achieve a ceramic fluorescent body exhibiting superior fluorescent characteristics and superior thermal characteristics with varied colors of emitted light.

A pore-free ceramic is provided that has a high modulus of elasticity and a low coefficient of thermal expansion. A process for producing a corresponding ceramic is also provided. The pore free ceramic is a dimensionally stable substrate material in applications subjected to temperature gradients including semiconductor manufacture.

Disclosed is a joined ceramic body comprising a first ceramic portion comprising a first ceramic, a second ceramic portion comprising a second ceramic, and a joining layer formed between the first ceramic portion and the second ceramic portion. The joining layer has a bond thickness of from 0.5 to 20 um and comprises silicon dioxide having a total impurity content of 20 ppm and less. A method of making the joined ceramic body and a joining material are also disclosed.

A method for producing a three-dimensional porous transition alumina catalyst monolith of stacked catalyst fibers, comprising: a) Preparing a paste in a liquid diluent of hydroxide precursor particles and/or oxyhydroxide precursor particles of transition alumina particles, all particles in the suspension having a number average particle size in the range of from 0.05 to 700 μm, b) extruding the paste nozzle(s) to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolith precursor, c) drying the precursor to remove the liquid diluent, d) performing a temperature treatment of the dried porous catalyst monolith precursor to form the transition alumina catalyst monolith, wherein no temperature treatment of the porous catalyst monolith precursor or porous catalyst monolith at temperatures above 1000° C. is performed and wherein no further catalytically active metals, metal oxides or metal compounds are applied to the surface.

A process for preparing roofing granules includes forming kaolin clay into green granules and sintering the green granules at a temperature of at least 900 degrees Celsius to cure the green granules until the crystalline content of the sintered granules is at least ten percent as determined by x-ray diffraction.

A pillar shaped honeycomb structure for induction heating, the honeycomb structure being made of ceramics and including: an outer peripheral wall; and a partition wall disposed on an inner side of the outer peripheral wall, the partition wall defining a plurality of cells, each of the cells penetrating from one end face to other end face to form a flow path, wherein a composite material containing a conductor and a non-conductor is provided in the cells in a region of 50% or less of the total length of the honeycomb structure from one end face, and wherein the conductor is a conductor that generates heat in response to a change in a magnetic field.

Process for treating a porous dental zirconia block with a coloring solution, the process comprising the steps of providing a porous dental zirconia block having two opposing surfaces, surface U and surface L, treating the upper surface U of the porous dental zirconia block with a coloring solution A.sub.1, wherein the coloring solution is provided with a volume VA.sub.1, turning the porous dental zirconia block around, treating the lower surface L with a coloring solution A.sub.2 which is provided with a volume VA.sub.2. wherein the coloring solutions A.sub.1 and A.sub.2 comprise a solvent and coloring ions, wherein the volume of at least one of the coloring solutions A.sub.1 or A.sub.2 is applied in portions, wherein the following condition is met: Vo=ΣV.sub.AX, with x≥2, with Vo being the overall amount of coloring solution used to infiltrate the porous dental zirconia block.