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.

Described are molds that include a ceramic material at a surface, as well as methods of forming the molds, and methods of using the molds; the ceramic material is constituted substantially, mostly, or entirely of three elemental components designated M, A, and X; the “M” component is at least one transition metal; the “A” component is one or a combination of Si, Al, Ge, Pb, Sn, Ga, P, S, In, As, Tl, and Cd; and the “X” component is carbon, nitrogen, or a combination thereof.

Invention relates to the production method of transparent polycrystalline silicon nitride ceramics which are obtained by sintering raw materials in powder form with powder metallurgy in the field of advanced technical ceramics and are used in the aviation and defense industry. More specifically, the present invention relates to a transparent polycrystalline silicon nitride ceramic material production method which allows obtaining transparent polycrystalline silicon nitride ceramic material at lower temperature and pressure values compared to the prior art in order to reduce production costs, facilitate the production process and reduce quantity/number of material and devices used, for this, unlike conventional sintering technique, spark plasma sintering technique in which heat is produced under high electrical current is used.

A method of manufacturing ceramic matrix composites includes producing chemical vapor deposition functionalized ceramic particles before injecting the functionalized ceramic particles into the CMC fabric. The functionalized ceramic particles are mixed with a binder solution and then dispensed into voids present between adjacent tows of the CMC fabric. Injecting the particles in the center of the voids reduces the size and volume fraction of the voids/defects, improving the homogeneity of surface texture, homogeneity of microstructure, and part model shape conformity.

A ceramic contains, in mass percent: Si.sub.3N.sub.4: 20.0 to 60.0%, ZrO.sub.2: 25.0 to 70.0%, and one or more oxides selected from MgO, Y.sub.2O.sub.3, CeO.sub.2, CaO, HfO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, SiO.sub.2, MoO.sub.3, CrO, CoO, ZnO, Ga.sub.2O.sub.3, Ta.sub.2O.sub.5, NiO, and V.sub.2O.sub.5: 5.0 to 15.0%. The ceramic has a coefficient of thermal expansion as high as that of silicon and an excellent mechanical strength, allows fine machining with high precision, and prevents particles from being produced.

A silicon nitride sintered body includes a silicon nitride crystal grains and grain boundary phases. Further, when D stands for width of the silicon nitride sintered body before being subjected to surface processing, relations between an average grain diameter dA and an average aspect ratio rA of the silicon nitride crystal grain in a first region from an outermost surface to a depth of 0 to 0.01D and an average grain diameter dB and an average aspect ratio rB of the silicon nitride crystal grain in a second region inside the first region satisfy the inequalities:

0.8≤ dA/dB≤ 1.2; and

0.8≤ rA/rB≤ 1.2.

A force-transmitting assembly includes a metal shaft having at least two longitudinally-extending grooves defined in an outer surface, and a metal hub having at least two longitudinally-extending grooves defined in an inner surface that surrounds the outer surface of the shaft. A plurality of discrete parts is disposed in the at least two longitudinally-extending grooves of the shaft and the hub in an interference-fit manner so as to transmit a torque from the shaft to the hub. Each of the discrete parts is composed of at least 50 mass % of technical ceramic selected from Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, ZrO.sub.2, or a mixture of two or more of Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, and ZrO.sub.2.

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 method for forming a complex shape three-dimensional ceramic article by printing a first layer of a first material having a first fraction of first ceramic particles and a first fraction of a first polymeric ceramic precursor. A second layer is printed such that it is at least partially disposed on the first layer of a second material having a second fraction of second ceramic particles and a second fraction of a second polymeric ceramic precursor. A composite of the first layer and the second layer is heated at a temperature sufficient to decompose the first and second polymeric ceramic precursors and sinter the article. During the sintering process, the first and second layers with different fractions of ceramic particles undergo different degrees of shrinkage, resulting in a tuneable mismatch of the bilayer structure and accurately achieving a targeted geometry.