Provided is a high-light transmittance zirconia sintered body, prepared by processing and forming a material for the high-light transmittance zirconia sintered body, and then performing high-temperature sintering in the atmosphere under normal pressure. The material for a high-light transmittance zirconia sintered body is prepared from zirconia powder and -aluminum oxide as raw materials, wherein the molar percentage of yttrium oxide in the zirconia powder is 4-6%. The high-light transmittance zirconia sintered body can be used for preparing a fixed dental prosthesis. The zirconia sintered body has a grain size of 0.1-0.7 m, and due to the dispersion and toughening by aluminum oxide, the zirconia sintered body has a higher strength and toughness. Pores in the zirconia powder can be eliminated by adding aluminum oxide. The zirconia sintered body has a higher light transmittance, and the prepared dentures are good in texture, good in jade-like appearance, and closer to the human teeth.

A method of forming one or more high temperature co-fired ceramic articles, comprising the steps of:

a) forming a plurality of green compacts, by a process comprising dry pressing a powder comprising ceramic and organic binder to form a green compact;
b) disposing a conductor or conductor precursor to at least one surface of at least one of the plurality of green compacts to form at least one patterned green compact;
c) assembling the at least one patterned green compact with one or more of the plurality of green compacts or patterned green compacts or both to form a laminated assembly;
d) isostatically pressing the laminated assembly to form a pressed laminated assembly;
e) firing the pressed laminated assembly at a temperature sufficient to sinter the ceramic layers together.

Zirconia dental ceramics exhibiting opalescence and having a grain size in the range of 10 nm to 300 nm, a density of at least 99.5% of theoretical density, a visible light transmittance at or higher than 45% at 560 nm, and a strength of at least 800 MPa.

A sintered bead with the following crystal phases, in percentages by mass based on crystal phases: 25%zircon, or Z.sub.1, 94%; 4%stabilized zirconia+stabilized hafnia, or Z.sub.2, 61%; monoclinic zirconia+monoclinic hafnia, or Z.sub.350%; corundum57%; crystal phases other than Z.sub.1, Z.sub.2, Z.sub.3 and corundum<10%; the following chemical composition, in percentages by mass based on oxides: 33%ZrO.sub.2+HfO.sub.2, or Z.sub.483.4%; HfO.sub.22%; 10.6%SiO.sub.234.7%; Al.sub.2O.sub.350%; 0%Y.sub.2O.sub.3, or Z.sub.5; 0%CeO.sub.2, or Z.sub.6; 0.3%CeO.sub.2+Y.sub.2O.sub.319%, provided that (1) CeO.sub.2+3.76*Y.sub.2O.sub.30.128*Z, and (2) CeO.sub.2+1.3*Y.sub.2O.sub.30.318*Z, with Z=Z.sub.4+Z.sub.5+Z.sub.6(0.67*Z.sub.1*(Z.sub.4+Z.sub.5+Z.sub.6)/(0.67*Z.sub.1+Z.sub.2+Z.sub.3)); MgO5%; CaO2%; oxides other than ZrO.sub.2, HfO.sub.2, SiO.sub.2, Al.sub.2O.sub.3, MgO, CaO, CeO.sub.2 and Y.sub.2O.sub.3<5.0%.

The present disclosure relates to novel boron carbide (B.sub.4C) composite material and the method of making and using the novel boron carbide (B.sub.4C) composite.

Zirconia dental ceramics exhibiting opalescence and having a grain size in the range of 10 nm to 300 nm, a density of at least 99.5% of theoretical density, a visible light transmittance at or higher than 45% at 560 nm, and a strength of at least 800 MPa.

A ring-shaped element for an etcher includes a body portion having an outer diameter surface connecting an outer contour of an upper surface and an outer contour of a bottom surface, and an inner diameter surface connected to an inner contour of the upper surface, and a mounting portion having an upper surface connected to the inner diameter surface of the body portion at a position lower than the upper surface of the body portion, and an inner diameter surface connecting an inner contour of the upper surface and an inner contour of a bottom surface. The upper surface of the mounting portion is stepped from the upper surface of the body portion to constitute a substrate mounting portion. The surface or entire body of the ring-shaped element includes necked boron carbide-containing particles, and the thermal conductivity of the ring-shaped element at 400 C. is 27 W/m.Math.K or less.

A zirconia sintered body is provided having a color tone equivalent to the color tone guides of various natural teeth and having the same aesthetics as a natural front tooth. The present invention provides a colored translucent zirconia sintered body comprising zirconia containing greater than 4.0 mol % and not greater than 6.5 mol % of yttria, less than 0.25 mol % of erbia, less than 2,000 ppm of iron oxide in terms of Fe.sub.2O.sub.3, less than 0.01 wt. % of cobalt oxide in terms of CoO, and less than 0.1 wt. % of alumina; the zirconia sintered body having a relative density of not less than 99.90%, a total light transmittance of not less than 25% and less than 40% for light having a wavelength of 600 nm at a sample thickness of 1.0 mm, and a strength of not less than 500 MPa.

A ceramic composite can include a first ceramic phase and a second ceramic phase. The first ceramic phase can include a silicon carbide. The second phase can include a boron carbide. In an embodiment, the silicon carbide in the first ceramic phase can have a grain size in a range of 0.8 to 200 microns. The first phase, the second phase, or both can further include a carbon. In another embodiment, at least one of the first ceramic phase and the second ceramic phase can have a median minimum width of at least 5 microns.

Aluminum nitride crystal particles, aluminum nitride powders containing the same, production processes for both of them, an organic polymer composition comprising the aluminum nitride crystal particles and a sintered body. Each of the aluminum nitride crystal particles has a flat octahedral shape in a direction where hexagonal faces are opposed to each other, which is composed of two opposed hexagonal faces and 6 rectangular faces, in which the average distance D between two opposed corners of each of the hexagonal faces is 3 to 110 m, the length L of the short side of each of the rectangular faces is 2 to 45 m, and L/D is 0.05 to 0.8; each of the hexagonal faces and each of the rectangular faces cross each other to form a curve without forming a single ridge; and the true destiny is 3.20 to 3.26 g/cm.sup.3.