Provided are: a mold material having improved fluidity and being capable of improving a filling rate of a forming mold during formation of a casting mold; and a mold material that gives cast products a favorable casting surface, effectively improves sand adhesion on cast products, and advantageously provides a casting mold having excellent strength. The mold material is formed as a coated sand in a wet state with spherical particles of silicone resin having binder repellency existing on its surface, by at least mixing a water-soluble inorganic binder in the liquid state having a viscosity of not more than 1000 cP, and the spherical particles of silicone resin, with a refractory aggregate.

A moulding material mixture with at least one refractory material and water glass as an inorganic binding agent is used for producing casting moulds. The binding agent is cured with the aid of a carbonyl compound that has a molecular weight greater than 88 g/mol and less than 200 g/mol and a boiling point at 1013 hPa greater than 20 C. and less than 200 C. The at least one carbonyl compound is introduced into the gas phase, or carried with the gas phase. The at least one carbonyl compound has the formula R.sup.1R.sup.2CO, where R.sup.1 is H or a C1 or C2 alkyl and R.sup.2 is a carboxyl group RC(O)O bonded via the oxygen atom, where R is a C1 to C3 hydrocarbon.

A casting slurry for the manufacture of shell molds, including powder particles and a binder, further including a surfactant. Use of such a casting slurry for the manufacture of a shell mold.

A method of reusing core sand includes crushing a core used for casting into granules, the core includes water glass as a binder, and the water glass includes water-soluble water glass and water-insoluble water glass; heating the core; detaching the water glass from the core sand; and separating and collecting the core sand from a mixture of the water glass and the core sand.

The invention relates to a molding mixture for producing casting molds for metalworking, a process for producing casting molds, casting molds obtained by the process and also their use. To produce the casting molds, a refractory mold raw material and a binder based on water glass are used. A proportion of a particulate metal oxide selected from the group consisting of silicon dioxide, aluminum oxide, titanium oxide and zinc oxide is added to the binder, particular preference being given to using synthetic amorphous silicon dioxide. The molding mixture contains a phosphate as essential constituent. The use of phosphate can improve the mechanical strength of casting molds at high thermal load.

A method for inorganic binder casting, comprising: selecting a Shape-Forming Material based on pre-determined manufacturing and shape characteristics, selecting a casting shape based on pre-determined design characteristics, and forming the Shape-Forming Material into a mold. The mold is coated with an inorganic binder solution at a pre-defined weight ratio and is dehydrated the Shape-Forming Material. The method further comprises pouring a hot liquid metal into the mold and allowing said hot liquid metal to cool to form a molded part. The Shape-Forming Material may be washed from said molded part with a solvent, the inorganic material and Shape-Forming Material reclaimed, reused, and the Shape-Forming Material reformed to a mold. The method further comprises recreating a liquid inorganic binder solution using the reclaimed inorganic material and recoating the Shape-Forming Material with the reclaimed inorganic binder solution.

The invention relates to a method for more quickly producing molds (2) or cores (2) for foundry purposes by adapting the specific electrical resistance in the selection of the core box to the mixture (9) of a molding material and of a water-containing binder, which binder, when dissolved, forms an electrolyte and has a sufficient electrical conductivity. It is essential to the invention that an electrically conductive material (7) for holding the mixture (9) is introduced into an electrically non-conductive housing (3), wherein the specific electrical conductivity of the material (7) at operating temperature (7) at least approximately corresponds to the specific electrical conductivity of the mixture (9) at temperatures between 100 C. and 130 C., and that electrical energy and thus heat are supplied to the material (7) via electrodes (10) arranged in/on the housing (3) (resistance heating principle), leading to curing of the mixture (9). Depending on the sand core, up to 30% shorter cycle times can be achieved.

The invention relates to a method for more quickly producing molds (2) or cores (2) for foundry purposes by adapting the specific electrical resistance in the selection of the core box to the mixture (9) of a molding material and of a water-containing binder, which binder, when dissolved, forms an electrolyte and has a sufficient electrical conductivity. It is essential to the invention that an electrically conductive material (7) for holding the mixture (9) is introduced into an electrically non-conductive housing (3), wherein the specific electrical conductivity of the material (7) at operating temperature (7) at least approximately corresponds to the specific electrical conductivity of the mixture (9) at temperatures between 100 C. and 130 C., and that electrical energy and thus heat are supplied to the material (7) via electrodes (10) arranged in/on the housing (3) (resistance heating principle), leading to curing of the mixture (9). Depending on the sand core, up to 30% shorter cycle times can be achieved.

The present invention provides a hydraulic composition for an additive manufacturing device having an excellent initial flexural strength development property and dimensional stability, the hydraulic composition for an additive manufacturing device including: 1.5 to 14 parts by mass of a polymer with respect to 100 parts by mass of an inorganic binder. In addition, the present invention preferably provides a hydraulic composition for an additive manufacturing device in which the inorganic binder contains 50 to 100 mass % of a calcium aluminate with respect to 100 mass % of the entire inorganic binder, and more preferably provides a hydraulic composition for an additive manufacturing device in which the inorganic binder contains 0 to 50 mass % of rapid hardening cement with respect to 100 mass % of the entire inorganic binder.

The present invention provides a hydraulic composition for an additive manufacturing device having an excellent initial flexural strength development property and dimensional stability, the hydraulic composition for an additive manufacturing device including: 1.5 to 14 parts by mass of a polymer with respect to 100 parts by mass of an inorganic binder. In addition, the present invention preferably provides a hydraulic composition for an additive manufacturing device in which the inorganic binder contains 50 to 100 mass % of a calcium aluminate with respect to 100 mass % of the entire inorganic binder, and more preferably provides a hydraulic composition for an additive manufacturing device in which the inorganic binder contains 0 to 50 mass % of rapid hardening cement with respect to 100 mass % of the entire inorganic binder.