Methods for preparing ceramic matrix composites using melt infiltration and chemical vapor infiltration are provided as well as the resulting ceramic matrix composites. The methods and products include the incorporation of sacrificial fibers to provide improved infiltration of the fluid infiltrant. The sacrificial fibers are removed, such as decomposed during pyrolysis, resulting in the formation of regular and elongate channels throughout the ceramic matrix composite. Infiltration of the fluid infiltrant can then take place using the elongate channels resulting in improved density and an improved ceramic matrix composite product.

A powder essentially composed of aggregates based on boron nitride, the powder exhibiting an overall chemical composition, as percentages by weight, including between 40 and 45% of boron, between 53 and 57% of nitrogen, less than 400 ppm by weight of calcium, less than 5%, in total, of other elements and more than 90% of boron nitride, limit included, as percentage by weight and on the basis of the combined crystalline phases, a mean circularity of greater than or equal to 0.90, a median pore size of less than or equal to 1.5 m and an apparent porosity of less than or equal to 55%.

A polycrystalline diamond comprising diamond particles, wherein: the content of the diamond particles is more than 99% by volume based on the total volume of the polycrystalline diamond: the median diameter d50 of the diamond particles is 10 nm or more and 200 nm or less; and the dislocation density of the diamond particles is 0.1?10.sup.15 m.sup.?2 or more and less than 2.0?10.sup.15 m.sup.?2.

A method for forming a ceramic matrix composite article includes forming by melt infiltration a ceramic matrix composite substrate inducing a ceramic fiber reinforcement material in a ceramic matrix material having a free silicon proportion and forming by chemical vapor infiltration a ceramic matrix composite outer layer including a ceramic fiber reinforcement material in a ceramic matrix material having no free silicon proportion disposed on at least a portion of the substrate.

Disclosed is a ceramic sintered body comprising yttrium oxide and zirconium oxide wherein the ceramic sintered body comprises not less than 75 mol % to not greater than 95 mol % yttrium oxide and not less than 5 mol % to not greater than 25 mol % zirconium oxide, wherein the ceramic sintered body comprises porosity in an amount of less than 2% by volume, wherein a density of the ceramic sintered body does not vary by more than 2% relative to theoretical density across a greatest dimension. The ceramic sintered body has a grain size of from 0.4 to less than 2 um as measured according to ASTM E1 12-2010. The ceramic sintered body may be machined into plasma resistant components for use in plasma processing chambers. Methods of making are also disclosed.

A silicon carbide-graphite composite is described, including (i) interior bulk graphite material and (ii) exterior silicon carbide matrix material, wherein the interior bulk graphite material and exterior silicon carbide matrix material inter-penetrate one another at an interfacial region therebetween, and wherein graphite is present in inclusions in the exterior silicon carbide matrix material. Such material may be formed by contacting a precursor graphite article with silicon monoxide (SiO) gas under chemical reaction conditions that are effective to convert an exterior portion of the precursor graphite article to a silicon carbide matrix material in which graphite is present in inclusions therein, and wherein the silicon carbide matrix material and interior bulk graphite material interpenetrate one another at an interfacial region therebetween. Such silicon carbide-graphite composite is usefully employed in applications such as implant hard masks in manufacturing solar cells or other optical, optoelectronic, photonic, semiconductor and microelectronic products, as well as in ion implantation system materials, components, and assemblies, such as beam line assemblies, beam steering lenses, ionization chamber liners, beam stops, and ion source chambers.

The invention relates to a refractory product, a batch for producing the product, a method for producing the product, and a use of the refractory product.

Methods for forming a ceramic matrix composite from a melt infiltrated and melt extracted preform that has residual silicon within open pore channels therein are provided. The method may include: introducing a carbon yielding resin into the open pore channels; heating the preform to produce elemental carbon from the carbon yielding resin within the open pore channels; and further heating the elemental carbon to react with the residual silicon to form SiC within the open pore channels to form the ceramic matrix composite.

The invention provides a cathode active material for use in a rechargeable battery, comprising a coated lithium nickel oxide powder or a coated lithium nickel manganese oxide powder, the powder being composed of primary particles provided with a glassy lithium silicate surface coating. A method for preparing the cathode active material comprises the steps of: providing a lithium transition metal based oxide powder, providing an alkali mineral compound comprising a Li.sub.2xSiO.sub.30.5x compound, wherein 0<x<2, mixing the lithium transition metal based oxide powder and the alkali mineral compound to form a powder-mineral compound mixture, and heat treating the mixture at a temperature T whereby lithium is extracted from the surface of the metal based oxide powder to react with the alkali mineral compound, and a glassy surface coating is formed comprising a Li.sub.2xSiO.sub.30.5x compound, wherein x<x<2.

An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 1 or more and 3 or less and an average sintered grain size of 20 m or more.