The present invention relates to geopolymer compositions, sintered geopolymer articles from the geopolymer compositions and processes for manufacturing sintered geopolymer articles from the geopolymer compositions. The invention provides a process of producing a sintered geopolymer article containing a sintered geopolymer composition, wherein the sintered geopolymer composition comprises a sintered geopolymeric matrix, said process comprising the steps of: (1) forming a geopolymer composition comprising at least one aluminosilicate precursor, an alkali activating agent and water, wherein in the geopolymer article, the aluminosilicate precursor particles are at least partially coated by the alkali activating agent; and (2) firing the geopolymer article to sinter the geopolymer composition, wherein the alkali activating agent is capable of at least partially activating and dissolving the aluminosilicate precursor particles during at least a portion of the firing step, and wherein the firing of the geopolymer article includes a geopolymer composition sintering stage.

Methods of making permeable aerogels (100) can include providing a sol mixture (110) comprising an organic scaffold, an inorganic aerogel precursor, and a first solvent. The organic scaffold can be insoluble in the first solvent. The sol mixture can react to form a gel (120) such that an interconnected channel network is formed which is at least partially defined by the organic scaffold. The first solvent in the gel can be exchanged (130) with a second solvent. The second solvent can dissolve the organic scaffold to expose the interconnected channel network. The gel can be dried (140) to form the permeable aerogel.

The invention relates to a refractory dry vibratable mix which sets at room temperature when water is added, for use in metallurgical vessels and comprising a refractory main component, a binder and a retarder.

Disclosed is a method for preparing an uncalcined geopolymer-based refractory material. The method includes the steps of mixing a mineral powder, a fly ash, a metakaolin, and silicon carbide whiskers by ball milling to form a milled material; mixing the milled material with a sodium water glass solution and water to form a slurry; and curing the slurry to obtain the uncalcined geopolymer-based refractory material. The uncalcined geopolymer-based refractory material thus prepared contains a geopolymer matrix formed of the mineral powder, the fly ash, and the metakaolin and the silicon carbide whiskers embedded in the geopolymer matrix.

The present invention is directed to a two-component (2K) anhydrous composition comprising a first component (1) comprising calcium aluminate cement; Ground Granulated Blast Furnace Slag (GGBS); and fumed silica; and a second component (2) comprising calcined bauxite; and fused zirconia mullite.

The present invention relates to a coating composition comprising: 10 to 80 wt % of cerium oxide comprising a dopant based upon the total weight of the composition, wherein said dopant is selected from iron oxide, cobalt oxide, chromium oxide, lanthanum oxide, or mixtures thereof, and the atomic ratio of dopant metal to cerium is in the range 0.01:1 to 0.5:1; and 10 to 50 wt % of binder based upon the total weight of the composition.

Provided are: a coated sand having improved fluidity and being capable of improving a filling rate of a casting mold to be obtained; and a coated sand for advantageously manufacturing a casting mold having excellent strength, which coated sand provides a casting mold with good mold-releasability and collapsibility, gives cast products a favorable casting surface, and effectively improves sand adhesion on cast products. The coated sand is formed as a dry granular material having fluidity at room temperature, in which the surface of a refractory aggregate is coated with a solid layer of a water-soluble inorganic binder, and spherical particles of silicone resin having binder-repellency exist on the surface of the binder layer, or form a layer on the surface of the binder layer, a part of the spherical particles being not covered with the water-soluble inorganic binder and being exposed.

A method of making a refractory article is provided. The method includes: a) mixing a binder system, a refractory charge, and a second colloidal binder to form an aqueous slurry; b) casting the aqueous slurry into a mold; c) subjecting the mold containing the aqueous slurry to a temperature that is lower than a slurry casting temperature for a time sufficient to form a green strength article; and d) firing the green strength article at a temperature of at least 450° C. for a time sufficient to achieve thermal homogeneity, thereby forming a refractory article. Refractory articles made in accordance with the method have a unique combination of pore structure and mechanical properties.

In one aspect, composite carbide compositions are described herein which can facilitate the efficient and/or economical manufacture of articles comprising SiC. Briefly, a composite carbide composition comprises silicon carbide (SiC) particles and a silica interparticle phase covalently bonded to the SiC particles.

An uncalcined geopolymer-based refractory material is provided, comprising a matrix of a geopolymer obtainable by polymerization of a mixture consisting of mineral powder, fly ash, and metakaolin; and SiC whiskers embedded in the geopolymer matrix. The material has excellent mechanical properties and high resistance to high temperatures and exhibits a ductile fracture mechanism instead of a brittle fracture mechanism.