A molding material in a powder-fixing lamination method includes an aggregate and a powdery precursor of a binder that binds the aggregate mutually. The aggregate is a casting sand, and the powdery precursor contains a hardening component and a hardening accelerating component. A molded product is manufactured using the molding material.

The present invention has solved the problems of conventional molding materials, and provides a hydraulic composition for additive manufacturing devices having high strength development, particularly high early strength development, and less generation of gas defect and graphite spheroidization defect. Specifically, the hydraulic composition for additive manufacturing devices of the present invention at least contains calcium aluminate. It is preferable that the hydraulic composition contain 0.5-10 parts by mass of gypsum with respect to 100 parts by mass of the calcium aluminate.

A curing agent for water glass molding comprises: ester; amorphous silica; and water. The amorphous silica is formed by means of a pyrolysis method and/or by means of a precipitation method. Also disclosed is a use of the curing agent for water glass molding in preparation of a casting mold and a mold core. Respective components of the curing agent comprising ester, amorphous silica and water are mixed at a high speed to form a suspension. Next, the suspension is applied to prepare a water glass self-hardening sand. The curing agent does not cause powder contamination, and can be measured and added conveniently. Also disclosed are a manufacturing method of the curing agent for water glass molding and a water glass self-hardening sand.

What is described is the use of a particulate material comprising, as its sole constituent or as one of multiple constituents, a particulate synthetic amorphous silicon dioxide having a particle size distribution with a median in the range from 0.1 to 0.4 ?m, determined by means of laser scattering, as additive for a molding material mixture at least comprising: a refractory mold base material having an AFS grain fineness number in the range from 30 to 100, particulate amorphous silicon dioxide having a particle size distribution with a median in the range from 0.7 to 1.5 ?m, determined by means of laser scattering, and water glass, for increasing the moisture resistance of a molding producible by hot curing of the molding material mixture. Also described are corresponding processes, mixtures and kits.

Clay materials useful as binding agents in green sandcasting and other molding processes are discussed, as well as methods of preparing such clay materials. The clay materials may be chemically treated. For example, a natural clay may be combined with one or more reducing agents, such that an amount of iron present as ferric iron (Fe.sup.3+) in the natural clay is at least partially reduced to ferrous iron (Fe.sup.2+) in the chemically-treated clay. The chemically-treated clay may exhibit greater water absorption, binding properties, and/or sintering properties as compared to an untreated, natural clay.

A composition which comprises a soluble or partially soluble phosphate, a refractory material and less than 1% of an oxide or hydroxide of magnesium or calcium. The composition may be mixed with water to form an investment casting slurry into which a wax pattern may be dipped. Slurry coated onto the pattern may be set by applying a stucco composition which comprises an oxide or hydroxide of magnesium or calcium. Coats of set slurry may be built up on the pattern to form an investment casting shell.

A composition for making cores and a process for metal casting, the composition comprising: a particulate refractory material; an inorganic binder comprising at least one alkali metal silicate; a pozzolanic additive; and a lustrous carbon former. The process includes forming a core from the composition and assembling a mould comprising the core and supplying molten metal.

Compositions useful for foundry processes such as green sandcasting are discussed. The compositions may comprise ball clay, bentonite, and a carbonaceous material. The ball clay may comprise leonardite and/or causticized lignite, e.g., as a portion of the natural ball clay deposit. The composition may further comprise sand, such that the resulting mixture may be formed into a green sand mold for use in casting molded articles. Incorporation of ball clay materials in the compositions may help to improve the quality of the casted article.

A method of forming a dry molding sand additive may include recovering a non-sand fraction from a foundry waste material and adding the non-sand fraction to a dry molding sand additive formulation to form a dry molding sand additive. Adding the non-sand fraction to the dry molding sand additive formulation may reduce the amount of fresh clay and carbon to produce the dry molding sand additive. A method of forming a molding sand additive may include recovering a waste molding sand additive composition having a clay or carbon content differing from a desired clay and carbon content, recycling the waste molding sand additive as a raw material in production of a fresh molding sand additive, and adjusting the amount of fresh clay or carbon added during production of the fresh molding sand additive to achieve the desired clay and carbon content.

The casting material may be formed around the casting core using a variety of conventional casting techniques including direct liquid metal infiltration, pressure assisted casting, and centrifugal casting among others.