A refractory article including a body having central opening extending through at least a portion of the body, the central opening having a receiving surface having a convex curvature. In an embodiment, the body can include a coupling protrusion extending from a portion of an upper surface of the body and a coupling depression on a portion of a bottom surface of the body.

A silicon nitride sintered body includes at least one black portion with a major axis of 10 μm or more in a field of view with a unit area of 5 mm×5 mm, when observing an arbitrary cross-section of the silicon nitride sintered body using a metallurgical microscope. A major axis of the black portion is Preferably 500 μm or less. The number of the black portion within the field of view with a unit area of 5 mm×5 mm is preferably 2 or more and 10 or less. A segregation portion of Fe is preferably included in the black portion.

Crystal pulling systems having composite polycrystalline silicon feed tubes, methods for forming such tubes, and methods for forming a single crystal silicon ingot with use of such tubes. The composite polycrystalline silicon feed tubes include quartz and at least one dopant. The composite polycrystalline silicon feed tube may be made by a slip cast method.

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.3”≤50%; corundum≤57%; 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.4”≤83.4%; HfO.sub.2≤2%; 10.6%≤SiO.sub.2≤34.7%; Al.sub.2O.sub.3≤50%; 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.3≤19%, provided that (1) CeO.sub.2+3.76*Y.sub.2O.sub.3≥0.128*Z, and (2) CeO.sub.2+1.3*Y.sub.2O.sub.3≤0.318*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)); MgO≤5%; CaO≤2%; 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%.

Shaped ceramic abrasive particles include a first surface having a perimeter having a perimeter comprising at least first and second edges. A first region of the perimeter includes the second edge and extends inwardly and terminates at two corners defining first and second acute interior angles. The perimeter has at most four corners that define acute interior angles. A second surface is disposed opposite, and not contacting, the first surface. A peripheral surface is disposed between and connects the first and second surfaces. The peripheral surface has a first predetermined shape. Methods of making the shaped ceramic abrasive particles, and abrasive articles including them are also disclosed.

Antiballistic armour plate includes a ceramic body including a hard material, provided, on its inner face, with a back energy-dissipating coating. The ceramic body is monolithic. The constituent material of the ceramic body includes grains of ceramic material having a Vickers hardness that is higher than 15 GPa, and a matrix binding the grains, the matrix including a silicon nitride phase and/or a silicon oxynitride phase, the matrix representing between 5 and 40% by weight of the constituent material of the ceramic body. The maximum equivalent diameter of the grains of ceramic material is smaller than or equal to 800 micrometres. The constituent material of the ceramic body has an open porosity that is higher than 5% and lower than 14%. The metallic silicon content in the material, expressed per mm of thickness of the body, is lower than 0.5% by weight.

A process for the manufacture of a refractory block including more than 80% zirconia, in percentage by weight based on the oxides. The process includes the following successive stages: melting, under reducing conditions, of a charge including more than 50% zircon, in percentage by weight, such as to reduce the zircon and obtain a molten material, application of oxidizing conditions to the molten material, casting of the molten material, and cooling until at least partial solidification of the molten material in the form of a block. Also, the process can include heat treatment of the block.

Systems and methods for fabrication of ceramics from celestial materials using microwave sintering and mechanical compression for space mining applications are disclosed. In one aspect, a chamber for sintering loose mineral material into solid ceramic shapes includes a plurality of zirconia insulting plates configured to clamp the mineral material and forming a cavity in which the mineral loose material is contained, and at least one dipole array configured to generate microwave energy and apply the microwave energy to the mineral material.

A manufacturing method of a sintered body is a manufacturing method of the sintered body which increases a temperature while applying an electric field to a ceramic compact. This method controls a current which flows to the ceramic compact so that a sintering rate becomes constant.

The present invention aims to provide a scintillator which has a short fluorescence decay time, whose fluorescence intensity after a period of time following radiation irradiation is low, and which shows largely improved light-transmittance. A scintillator represented by the following General Formula (1), the scintillator including Zr, having a Zr content of not less than 1500 ppm by mass therein, and being a block of a sintered body. Q.sub.xM.sub.yO.sub.3z:A . . . (1) (wherein in General Formula (1), Q includes at least one or more kinds of divalent metallic elements; M includes at least Hf; and x, y, and z independently satisfy 0.5≤x≤1.5, 0.5≤y≤1.5, and 0.7≤z≤1.5, respectively).