A powder intended for the manufacture of a sintered dental article, The powder has a chemical analysis such that, as weight percentages based on the oxides: Al.sub.2O.sub.3: 0.2%, oxides other than ZrO.sub.2, HfO.sub.2, Yb.sub.2O.sub.3, Y.sub.2O.sub.3 and Al.sub.2O.sub.3: <0.5%, and ZrO.sub.2+HfO.sub.2+Yb.sub.2O.sub.3+Y.sub.2O.sub.3: balance to 100%, with HfO.sub.2<2%. The contents of Yb.sub.2O.sub.3 and Y.sub.2O.sub.3, as molar percentages based on the sum of ZrO.sub.2, HfO.sub.2, Yb.sub.2O.sub.3 and Y.sub.2O.sub.3, being such that Yb.sub.2O.sub.3≥1%, 0.5%≤Y.sub.2O.sub.3<2%, and Yb.sub.2O.sub.3+Y.sub.2O.sub.3≤5.5%. The powder has a specific surface area of greater than or equal to 5 m.sup.2/g and less than or equal to 16 m.sup.2/g. The powder has a median size of greater than or equal to 0.1 μm and less than or equal to 0.7 μm.

The present disclosure provides a method of making a ceramic article. The method includes (a) obtaining a photopolymerizable slurry or sol including a plurality of ceramic particles distributed in the photopolymerizable slurry or sol and (b) selectively polymerizing the photopolymerizable slurry or sol using actinic radiation and continuous movement of a build substrate through the photopolymerizable slurry or sol to form a gelled article. The method also includes (c) extracting solvent from the gelled article to form an aerogel article or a xerogel article; (d) heat treating the aerogel article or the xerogel article to form a porous ceramic article; and (e) sintering the porous ceramic article to form a sintered ceramic article. The sintered ceramic article exhibits a particular density. Further, additive manufactured ceramic articles are provided that exhibit a particular density, opacity, or both. Preferably, all cross-sectional portions of an interior of the ceramic article having selected dimensions are free of a frequency analysis signal maxima larger than a background signal.

A rim-rotor assembly has an annular structure including a composite rim and a hub. Blades project from the hub, tips of the blades contacting the annular structure, the blades configured to be loaded in compression against the annular structure. A thermal barrier is in the annular structure, the thermal barrier defining at least part of a radially inward surface of the annular structure. The tips of the blades contact the thermal barrier, the thermal barrier being a thermal barrier coating.

The present invention discloses an Al.sub.2O.sub.3-based ceramic welding sealing component and a preparation method thereof, and relates to the technical field of metalized ceramic processing. The Al.sub.2O.sub.3-based ceramic welding sealing component disclosed in the present invention comprises a ceramic matrix and a metallized layer. The ceramic matrix is made from raw materials such as an inorganic fiber-aluminum oxide 3D network matrix, yttrium oxide, silicon oxide, titanium oxide, an additive, a binder and a dispersant, through steps such as preparation of the inorganic fiber-aluminum oxide 3D network matrix, mixing, pelletizing, primary sintering and secondary sintering; and the raw materials of the metallized layer comprise titanium powder, tungsten powder, molybdenum oxide, boron oxide, yttrium oxide and an organic binder. Al.sub.2O.sub.3-based ceramic welding sealing component provided by the present invention has high efficiency of space filling and tensile strength, excellent tensile strength, toughness and high-temperature resistance.

A zirconia powder in which when a stabilizer is Y.sub.2O.sub.3, a content thereof is 1.4 mol % or more and less than 2.0 mol %; when the stabilizer is Er.sub.2O.sub.3, a content thereof is 1.4 mol % or more and 1.8 mol % or less; when the stabilizer is Yb.sub.2O.sub.3, a content thereof is 1.4 mol % or more and 1.8 mol % or less; and when the stabilizer is CaO, a content thereof is 3.5 mol % or more and 4.5 mol % or less; and in a range of 10 nm or more and 200 nm or less in a pore distribution, a peak top diameter of a pore volume distribution is 20 nm or more and 120 nm or less, a pore volume is 0.2 ml/g or more and less than 0.5 ml/g, and a pore distribution width is 30 nm or more and 170 nm or less.

A zirconia powder containing a stabilizer, and having a specific surface area of 20 m.sup.2/g or more and 60 m.sup.2/g or less and a particle diameter D.sub.50 of 0.1 μm or more and 0.7 μm or less, in which in a range of 10 nm or more and 200 nm or less in a pore distribution based on a mercury intrusion method, a peak top diameter in a pore volume distribution is 20 nm or more and 85 nm or less, a pore volume is 0.2 ml/g or more and less than 0.5 ml/g, and a pore distribution width is 40 nm or more and 105 nm or less.

A dielectric composition includes dielectric particles and first segregations. The dielectric particles each include a perovskite compound represented by ABO.sub.3 as a main component. The first segregations each include at least Ba, P, and O. A molar ratio (Ba/Ti) of Ba to Ti in the first segregations is 1.20 or more.

In a silicon nitride substrate including a silicon nitride sintered body including silicon nitride crystal grains and a grain boundary phase, a plate thickness of the silicon nitride substrate is 0.4 mm or les, and a percentage of a number of the silicon nitride crystal grains including dislocation defect portions inside the silicon nitride crystal grains in a 50 μm×50 μm observation region of any cross section or surface of the silicon nitride sintered body is not less than 0% and not more than 20%. Etching resistance can be increased when forming the circuit board.

An improved ceramic material for heat insulation with selection of specific stabilizers and adapted proportions, includes zirconium oxide with 0.2 wt. % to 8.0 wt. % of the base stabilizers: yttrium oxide (Y.sub.2O.sub.3), hafnium oxide (HfO.sub.2), cerium oxide (CeO.sub.2), calcium oxide (CaO), and/or magnesium oxide (MgO), wherein at least yttrium oxide (Y.sub.2O.sub.3) is used, and optionally at least one of the additional stabilizers: 0.2 wt. % to 20 wt. % of erbium oxide (Er.sub.2O.sub.3) and/or ytterbium oxide (Yb.sub.2O.sub.3).

The present invention relates to a method for manufacturing a silicon nitride substrate and, more specifically, comprises the steps of: forming a slurry by mixing silicon nitride powder, a ceramic additive, and a solvent; molding the slurry to form sheets; sandwiching at least one of the sheets between a lower plate and an upper plate to form a stacked structure; degreasing the stacked structure; and sintering the stacked structure. At least one of the lower plate and the upper plate comprises a plurality of protrusions provided on one surface thereof, and the protrusions extend in parallel to each other in one direction.