Disclosed herein is a casting core for casting molds, the casting core comprising an inner core and an outer core arranged around the inner core. The outer core contains or consists of ceramic particles bound with a binder. The inner core contains ceramic particles bound with a binder and additionally one or more placeholder elements. The placeholder element(s) is/are at least partially thermally decomposable. Also disclosed is a method for producing the casting core and use of the casting core.

A structure for manufacturing castings, containing an inorganic fiber, a layered clay mineral, and an inorganic particle other than the layered clay mineral and having an organic content of 5 mass % or lower or having a mass loss of 5 mass % or lower when heated at 1000° C. for 30 minutes. The inorganic particle preferably contains one or more selected from obsidian, graphite, and mullite. The inorganic fiber preferably contains carbon fiber. The inorganic fiber preferably has an average length of 0.5 to 15 mm. The layered clay mineral preferably contains one or more selected from bentonite and montmorillonite.

Foundry casting elements and methods of forming the same, the methods including: forming an aqueous slurry including an inorganic binder precursor, shaping the slurry using a pattern, curing the shaped slurry using a low temperature solidification process to form a casting element, and removing the pattern from the casting element.

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 casting slurry for producing shell molds for casting parts includes a metal alloy, the slurry includes powder particles and a binder, the binder includes colloidal yttrium oxide, and the powder particles includes calcia-stabilized zirconia.

A casting green sand mold comprising at least a pair of green sand mold parts each having a cavity portion, which are stacked with their cavity portions aligned to form a metal-melt-receiving cavity; each of the green sand mold parts being formed by casting sand containing a binder and water; a hardening-resin-based coating layer being formed on at least the cavity portion of each green sand mold part; the coating layer having gas-permeable pores having sufficient permeability to permit a gas generated by pouring a metal melt to escape; and a water content in a surface layer including the coating layer in a range from the cavity surface to the depth of 5 mm being smaller than that in the inner portion of the green sand mold.

The object of the present invention is to provide an embedding material composition for casting that makes it possible to conduct a favorable casting in the case where casting is conducted using a resin pattern that is different from a conventional wax pattern in disappearance temperature and disappearance behaviors through “rapid heating” excellent in treatment efficiency. The present invention relates to an embedding material composition for casting not using a heat-expandable refractory material as a main component, comprising: a binder; and a non-heat-expandable refractory material having an average particle diameter of 5 to 20 μm as main components, in which a content of the binder is 25 to 40 parts by mass and a content of the non-heat-expandable refractory material is 60 to 75 parts by mass in the case where the total amount of the main components is 100 parts by mass, and the present invention also relates to a casting process using the embedding material composition for casting.

A method of preparing a unique foundry premix composition that has a low bulk density of 30-45 lbs/ft.sup.3 and contains fine particles with an average particle size of 85-100 μm is described. The unique foundry premix composition is produced by using specially designed assemblies of mechanical equipment with improved efficiency so that the premix can be prepared at a site closer to a foundry. As a result, increase in premix density caused by handling and shipping across a long distance from a traditional premix manufacturing facility to a foundry can be suppressed; transportation cost can be saved; and safety would be of less concern. The use of the foundry premix composition to prepare a sand molding medium for casting molded articles is also described.

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 μm, 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 μm, 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.

An investment powder which is safer than conventional powders comprising tricalcium phosphate, and being substantially or entirely free of free silica in the respiratory portion yet providing an overall expansion at 750° C. of 1% or higher sufficient to prevent mould cracking during casting. A method of making a casting comprising forming a slurry by mixing a gypsum bonded investment powder with water, pouring the slurry into a stainless steel flask around a low melting point material model, allowing the slurry to set to define a mould, heating the mould to burn out the model and casting material into the mould wherein the stainless steel flask consists of a 400 series martensitic stainless steel.