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.

Multi-step milling processes to prepare cBN composite powder forms a first powder mixture by adding a binder and a first cBN component, mills the first powder mixture for a first time period, combines a second cBN component with the milled first powder mixture to form a second powder mixture, and mills the second powder mixture for a second time period (less than the first time period) to form the cBN composite powder. A ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is at least 3.0. Two-step milling with different milling times for the two cBN component fractions controls the amount of mill debris in the cBN composite powder mixture. Further processing of the cBN composite powder under HPHT conditions forms a cBN-based ceramic with an average value of a cBN particle free diameter of less than 2.0 microns.

A filter for the filtration of a fluid, such as a liquid, includes or is composed of a support element made of a porous ceramic material, the element exhibiting a tubular or parallelepipedal shape delimited by an external surface and including, in its internal portion, a set of adjacent channels with axes parallel to one another and separated from one another by walls of the porous inorganic material, in which at least a portion of the channels and/or at least a portion of the external surface are covered with a porous separating membrane layer, wherein the separating membrane layer is made of a material essentially composed of silicon carbide (SiC), and the content by weight of elemental nitrogen of the layer constituting the porous separating membrane layer is between 0.1% and 2%.

An insulator composition includes Al.sub.2O.sub.3 having a particle size of 120 to 500 nm. The insulator composition has a strength of 400 to 740 MPa and a particle size of 1 μm or less.

A particle mixture having: ZrO.sub.2+HfO.sub.2+Y.sub.2O.sub.3+CeO.sub.2; 0%≤Al.sub.2O.sub.3≤1.5%; other oxides than ZrO.sub.2, HfO.sub.2, Y.sub.2O.sub.3, CeO.sub.2 and Al.sub.2O.sub.3: between 0.5% and 12%. The contents of Y.sub.2O.sub.3 and CeO.sub.2, on the basis of the sum of ZrO.sub.2, HfO.sub.2, Y.sub.2O.sub.3 and CeO.sub.2, being such that 1.8%≤Y.sub.2O.sub.3≤3% and 0.1%≤CeO.sub.2≤0.9%. The mixture includes between 0.5% and 10% of particles of an oxide pigment. The content of other oxides and which are not included in the oxide pigment being less than 2%. The particles of the oxide pigment including, for more than 95%, of a material chosen from: oxide(s) of perovskite structure or equivalent of precursor(s) of these oxides, oxides of spinal structure or an equivalent amount of precursor(s) of these oxides, and oxides of hematite structure E.sub.2O.sub.3, oxides of rutile structure FO.sub.2, with “E” and “F” being chosen.

Provided is a crystalline silicon carbide fiber containing silicon carbide, boron nitride, and zirconium carbide and having a content of Si of 64% by weight or more and a content of C of 28% by weight or more, in which the average particle size of SiC crystal grains is 100 nm or more.

The present disclosure provides processes for forming angular ceramic particles. In at least one embodiment, a process for forming angular ceramic particles includes providing a slurry having a ceramic raw material having alumina. The process includes atomizing the slurry into droplets and coating seeds comprising alumina with the droplets to form green pellets. The process includes sintering the green pellets to form sintered pellets. The process includes breaking the sintered pellets to form the angular ceramic particles comprising a sintered ceramic material. The angular ceramic particles can have an abrasion loss that is less than that of angular ceramic particles formed by crushing the green pellets prior to sintering.

A process of forming a sintered article includes heating a green portion of a tape of polycrystalline ceramic and/or minerals in organic binder at a binder removal zone to a temperature sufficient to pyrolyze the binder; horizontally conveying the portion of tape with organic binder removed from the binder removal zone to a sintering zone; and sintering polycrystalline ceramic and/or minerals of the portion of tape at the sintering zone, wherein the tape simultaneously extends through the removal and sintering zones.

Disclosed is a method of manufacturing a porous ceramic body, which includes: (S1) mixing silica powders having a particle size of 0.045˜0.5 mm, zircon flour and wax, thus preparing a ceramic mixture; (S2) placing the ceramic mixture into a mold, thus producing a green body; and (S3) sintering the green body at high temperature, thus obtaining a porous ceramic body, wherein the silica having a particle size of 0.1˜0.5 mm is contained in an amount of 50˜80 wt % based on the total weight of the porous ceramic body; and also which produces a bulk porous ceramic body having good strength and leaching properties with excellent dimensional stability and shape stability.

A porous sintered clay mineral matrix that contains aluminum and is doped with 0.1-20 mol %, based on the amount of the aluminum, one or more transition metals, one or more post-transition metals, one or more rare earth metals, or a combination thereof. An example is a kaolinite matrix. The matrix can be made from a calcined clay mineral powder that contains aluminum and is doped with at least one of these metals. Also disclosed are methods of preparing the above-described matrix and powder.