An air stable solid garnet composition, comprising: a bulk composition and a surface protonated composition on at least a portion of the bulk composition as defined herein, and the protonated surface composition is present on at least a portion of the exterior surface of the bulk composition at a thickness of from 0.1 to 10,000 nm. Also disclosed is a composite electrolyte structure, and methods of making and using the composition and the composite electrolyte structure.

An air stable solid garnet composition, comprising: a bulk composition and a surface protonated composition on at least a portion of the bulk composition as defined herein, and the protonated surface composition is present on at least a portion of the exterior surface of the bulk composition at a thickness of from 0.1 to 10,000 nm. Also disclosed is a composite electrolyte structure, and methods of making and using the composition and the composite electrolyte structure.

An alumina fiber aggregate that is formed of alumina short fibers and has been subjected to needling treatment, wherein the alumina short fibers have an average fiber diameter of 6.0 μm or more and 10.0 μm or less and a specific surface area of 0.2 m.sup.2/g or more and 1.0 m.sup.2/g or less, and a residual percentage (%) of high-temperature-cycle opened gap pressure of the alumina fiber aggregate is 45% or more. A value obtained by subtracting twice the standard error of a length-weighted geometric mean diameter of fiber diameters of the alumina short fibers from the length-weighted geometric mean diameter is 6.0 μm or more. A proportion of alumina short fibers having a fiber diameter of more than 10.0 μm is preferably 5.0% or less on a number basis.

A method for the manufacture of a three-dimensional object using a refractory matrix material is provided. The method includes the additive manufacture of a green body from a powder-based refractory matrix material followed by densification via chemical vapor infiltration (CVI). The refractory matrix material can be a refractory ceramic (e.g., silicon carbide, zirconium carbide, or graphite) or a refractory metal (e.g., molybdenum or tungsten). In one embodiment, the matrix material is deposited according to a binder-jet printing process to produce a green body having a complex geometry. The CVI process increases its density, provides a hermetic seal, and yields an object with mechanical integrity. The residual binder content dissociates and is removed from the green body prior to the start of the CVI process as temperatures increase in the CVI reactor. The CVI process selective deposits a fully dense coating on all internal and external surfaces of the finished object.

A method for the manufacture of a three-dimensional object using a refractory matrix material is provided. The method includes the additive manufacture of a green body from a powder-based refractory matrix material followed by densification via chemical vapor infiltration (CVI). The refractory matrix material can be a refractory ceramic (e.g., silicon carbide, zirconium carbide, or graphite) or a refractory metal (e.g., molybdenum or tungsten). In one embodiment, the matrix material is deposited according to a binder-jet printing process to produce a green body having a complex geometry. The CVI process increases its density, provides a hermetic seal, and yields an object with mechanical integrity. The residual binder content dissociates and is removed from the green body prior to the start of the CVI process as temperatures increase in the CVI reactor. The CVI process selective deposits a fully dense coating on all internal and external surfaces of the finished object.

A sintered composite ceramic, including: a lithium-garnet major phase; and a grain growth inhibitor minor phase, such that the grain growth inhibitor minor phase has a metal oxide in a range of 0.1 wt. % to 10 wt. % based on the total weight of the sintered composite ceramic.

A process for preparing roofing granules includes forming kaolin clay into green granules and sintering the green granules at a temperature of at least 900 degrees Celsius to cure the green granules until the crystalline content of the sintered granules is at least ten percent as determined by x-ray diffraction.

A spark plug according to one embodiment of the present invention includes an insulator formed of an alumina-based sintered body, wherein the insulator contains 90 wt % or more of an aluminum component in terms of oxide, and wherein crystal grains of the insulator has an average grain size of 1.5 mm or smaller and a grain size standard deviation of 1.2 μm or smaller.

A process for preparing roofing granules includes forming kaolin clay into green granules and sintering the green granules at a temperature of at least 900 degrees Celsius to cure the green granules until the crystalline content of the sintered granules is at least ten percent as determined by x-ray diffraction.

Disclosed are a pseudo-ternary thermoelectric material, a method of manufacturing the pseudo-ternary thermoelectric material, a thermoelectric element, and a thermoelectric module. The pseudo-ternary thermoelectric material includes bismuth (Bi), antimony (Sb), tellurium (Te), and selenium (Se), and a composition ratio thereof is Bi.sub.xSb.sub.2-xTe.sub.3 in which 0.3≤x≤0.6 or (Bi.sub.2Te.sub.3).sub.1-x-y(Sb.sub.2Te.sub.3).sub.x(Sb.sub.2Se.sub.3).sub.y in which 0<x<1 and 0.001≤y≤0.05.