A preform intended for the production of a dental prosthesis. The preform includes a group of agglomerated ceramic, glass-ceramic or glass particles, such that, as volume percents: more than 40% and less than 90% of the particles of said group have a size greater than 0.5 ?m and less than 3,5 ?m, said particles hereinafter being denoted enamel particles, and more than 10% and less than 60% of the particles of said group have a size greater than 3.5 ?m and less than 5.5 ?m, said particles hereinafter being denoted dentine particles. The microstructure of the preform is such that there is an axis X, termed axis of variation, along which the Ve/(Ve+Vd) ratio changes continuously, Ve and Vd denoting the volume percents of enamel particles and of dentine particles, respectively. The enamel and dentine particles representing, together, more than 90% of the volume of the agglomerated particles.

A sintered molded article includes a ceramic of /-sialon having a grain boundary phase, the grain boundary phase containing at least one hard material formed in situ as an additional phase. A method for the production of the sintered molded article uses at least the following compounds as a starting material: Si.sub.3N.sub.4, AlN, and, if applicable, Al.sub.2O.sub.3, at least one oxide of the rare earths, and at least one oxide of the element titanium.

The disclosure provides a gradient structure cubic boron nitride composite sheet and a preparation method thereof. The gradient structure cubic boron nitride composite sheet consists of a cemented carbide substrate, a gradient transition layer, and a CBN layer from bottom to top. The gradient transition layer consists of N gradient layers, and the N is 4 to 18. From bottom to top, there are sequentially a first gradient layer, a second gradient layer, an Nth gradient layer, and so on. Any of the gradient layers consists of CBN and cemented carbide, in which the volume fraction of the cemented carbide in the Nth layer is 5 to 30% less than the volume fraction of the cemented carbide in the N?1th layer, and the volume fraction of the CBN in the Nth layer is 5 to 30% more than the volume fraction of the CBN in the N?1th layer.

A method for preparing a shell-bionic ceramic tool and a shell-bionic ceramic tool, wherein the shell-bionic ceramic tool includes alternating stacks of ceramic powders with different components, pressing a ceramic green body using a cold briquetting method, carrying out pre-pressing once using a graphite indenter on a working surface thereof after each layer of the ceramic powder being loaded, and pressing a last layer using a graphite rod, and then pressing a whole ceramic green body with a certain pressure to promote a bonding of the layers of ceramic powder, which in turn gives a complex shape to an interface between the layers, increases a bonding area between the layers, and plays the role of hindering crack expansion, extending the crack expansion path, and improving the bonding strength of the interface; after then, hot-pressed sintering is used to densify the ceramic green body to obtain the shell-bionic ceramic tool.

A method of improving the flow of a proppant pack or gravel pack comprises: introducing into a subterranean formation or a well a plurality of ceramic particles, the ceramic particles comprising about 0.1 wt. % to about 25 wt. % of a rare earth-containing compound, based on the total weight of the ceramic particles; and forming a proppant pack or gravel pack comprising the plurality of the ceramic particles; wherein the proppant pack or gravel pack improves fluid flow as compared with a reference proppant pack or gravel pack formed from otherwise identical ceramic particles except for being free of the rare earth-containing compound.

A method for manufacturing a positive active material is provided. The method includes forming a positive active material precursor including nickel, mixing and firing the positive active material precursor and lithium salt to form a preliminary positive active material particle, forming a coating material including fluorine on the preliminary positive active material particle by dry-mixing the preliminary positive active material particle with a coating source including fluorine, and manufacturing a positive active material particle by thermally treating the preliminary positive active material particle on which the coating material is formed.

Disclosed herein are embodiments of a porous aluminum oxide thin film having a surface RMS roughness value of less than 1 nm. The thin film may also comprise phosphorus. The disclosed thin films may have a refractive index of from 1 to 2, such as from 1 to 1.5. Also disclosed are embodiments of as method for making the disclosed thin films, comprising forming an aqueous solution of the alumina precursor, a surfactant and optionally a phosphorus-containing precursor, and depositing the solution on a substrate.

A ferroelectric film a plurality of fired films is provided. E each of the plurality of fired films is made of metal oxide in a perovskite structure including Pb, Zr, and Ti, a total content of Li, Na, and K in the each of the plurality of fired films is 3 mass ppm or less, and the total content of Li, Na, and K on one surface of each of the plurality of fired films is 5 times or more of the total concentration of Li, Na, and K on other surface of each of the plurality of fired films.

A ceramic matrix composite article includes a melt infiltration ceramic matrix composite substrate comprising a ceramic fiber reinforcement material in a ceramic matrix material having a first free silicon proportion, and a melt infiltration ceramic matrix composite outer layer comprising a ceramic fiber reinforcement material in a ceramic matrix material having a second free silicon proportion disposed on an outer surface of at least a portion of the substrate, or a polymer impregnation and pyrolysis ceramic matrix composite outer layer comprising a ceramic fiber reinforcement material in a ceramic matrix material having a second free silicon proportion disposed on an outer surface of at least a portion of the substrate. The second free silicon proportion is less than the first free silicon proportion.

Techniques and compositions are disclosed for composite feedstocks with powder/binder systems suitable for three-dimensional printing, such as fused filament fabrication. The composite feedstocks may include a jacket about a core, with at least the core including a powder material suspended in a binder system and the jacket having a hardness or toughness greater than a hardness or toughness of the core for the feedstock. In general, the harder jacket may protect the core from unintended deformation or damage during transportation, storage, or use. For example, the difference in hardness or toughness between the jacket and the core may facilitate gripping the feedstock (e.g., by gear drives or the like) with a higher amount of force than is otherwise applicable if the feedstock were composed of the core alone, without damaging the core, during a fused filament fabrication process or another additive manufacturing process.