Methods for forming ceramic cores are disclosed. A ceramic core formed using the method of the present application includes a silica depletion zone encapsulating an inner zone. The inner zone includes mullite and the silica depletion zone includes alumina. The method includes heat-treating a ceramic body in a non-oxidizing atmospheric condition for an effective temperature and time combination at a pressure less than 10 atmosphere to form the silica depletion zone at a surface of the ceramic core.

One embodiment provides an article, comprising: an inner container having a cavity, the inner container comprising a ceramic; and an outer container, the outer container comprising a susceptor; wherein at least a portion of an outer surface of the inner container is in contact with an inner surface of the outer container, and wherein the inner container is removable from the mold. Methods of melting using the present article are also provided.

Described is a two-component system, particularly for forming an adhesive, which is suitable, for example, for applications in the foundry industry and in the construction industry.

Disclosed is a method for manufacturing a hydraulic binder including a calcium aluminate, which involves: a) providing a composition including a lime C source compound and an alumina source compound, the composition including at most 95% lime C and alumina, and at least 23% alumina, by weight relative to the total weight of dry matter of the composition; b) placing the composition provided in step a) in a moisture-saturated environment, at a hydration temperature of between 40? C. and 150? C., so as to precipitate hydrated phases containing at least one aluminium oxide combined with a calcium oxide and with water; and c) subjecting the precipitates obtained in step b) to a baking temperature of between 200? C. and 1300? C., for at least 15 minutes.

A self-bonding refractory powder product for use in making a slurry for investment casting molds comprising a coarse refractory powder; a Nano-sized powder; and an organic polymer powder, wherein it does not require aqueous colloidal silica to produce slurries used to build investment casting molds. The Nano-sized powder comprises fumed alumina, boehmite, fumed silica, or fumed titanium oxide or combinations thereof. The coarse refractory powder comprises milled zircon, tabular alumina or fused alumina, fused silica, alumino-silicate, zirconia, and yttria or combinations thereof. The organic polymer powder comprises a cellulose-based material.

What are described are the use of a refractory coating composition for production of cores for diecasting, a kit for production of cores for use in diecasting, a method of producing cores for use in diecasting, cores for use in diecasting, and the use of such cores in diecasting, especially of lightweight metals.

Compositions useful for foundry processes such as green sand casting are discussed. The compositions may comprise an aggregate, at least one inorganic binding agent, and at least one high aspect ratio silicate. For example, the composition may comprise sand, one or more clay materials serving as a binding agent, and a high aspect ratio silicate chosen from mica, talc, or a combination thereof. The composition may be formed into a green sand mold for use in casting molded articles. Incorporation of the high aspect ratio silicate may help to improve the quality of the casted article.

A filter element, useful for filtering molten metals and the like, is made from a precursor or template (10) having at least two layers (20). Each layer is assembled from three-dimensional geometric cages (22), joined in fixed relationship to each other: Some embodiments include a peripheral member (26) that encompasses the layer. In such cases, spacer members (28) can span the peripheral members to hold the layers in fixed spaced-apart relationship. In other embodiments, at least some of the cages in adjacent layers can be joined in fixed relationship, providing the spaced-apart relationship. The cages can be built from linear segments of a material joined in a pattern based on the edges of the geometric solid. The template may be formed by an automated technique, such as three-dimensional printing. If manufactured from a polymer, the precursor is coated with a ceramic slurry and calcined to provide the filter element.

A method for producing granulates, particularly for use as thermal insulation for a metal melt may include mixing a powdery mineral with a binder, and the mixture may be granulated in order to produce a semi-finished product. The granulate mixture or the semi-finished product may be heated rapidly to a temperature above the melting temperature or decomposition temperature of the binder, which may be in the form of a salt, so that the binder decomposes, whereby gas is released and the volume increases. The apparent density of the granulate mixture may decrease, and therefore the apparent density of the finished product may decrease with respect to the semi-finished product.

A granular material may include a granular core including quicklime, the granular core having an overall concentration of CaO and MgO equal to or greater than 80% by weight. Optionally, a hydrophobic coating may cover the granular core. The granular core has compressive load until rupture equal to or greater than 50 N/granule, a slaking time t.sub.50 in water not exceeding 10 minutes, when the concentration of MgO is greater than 5% by weight with respect to the weight of the granular core, and a slaking time t.sub.60 in water not exceeding 6 minutes, when the concentration of MgO is less than or equal to 5% by weight with respect to the weight of the granular core. The present disclosure further relates to a process for preparing the granular material and to the use of the granular material in a metallurgical process or in the treatment of agricultural soil.