To provide a binder composition for molding, by which a mold made of aggregate has an excellent resistance to moisture. The binder composition for molding contains a water-soluble binder and at least one kind of lithium salt that is selected from a group of lithium silicate, lithium oxide, lithium hydroxide, lithium carbonate, lithium bromide, lithium chloride, lithium nitrate, and lithium nitrite.

The present invention is a granular material that can be well recoated regardless of the type of the granular material, and enables a refractory aggregate in an unprinted portion to be used without any regeneration process, in the manufacture of a three-dimensional laminated and shaped mold. This granular material is a granular material for use in three-dimensional laminated mold shaping, and obtained by adding a material that causes a hydration reaction having a moisture absorbing function and generates a catalytic effect to a coating material mixed with or coated with an acid as a catalyst which activates and hardens an organic binder for binding the granular material.

The present invention is a granular material that can be well recoated regardless of the type of the granular material, and enables a refractory aggregate in an unprinted portion to be used without any regeneration process, in the manufacture of a three-dimensional laminated and shaped mold. This granular material is a granular material for use in three-dimensional laminated mold shaping, and obtained by adding a material that causes a hydration reaction having a moisture absorbing function and generates a catalytic effect to a coating material mixed with or coated with an acid as a catalyst which activates and hardens an organic binder for binding the granular material.

A method of casting an article from a molten metal including: admitting molten metal to a mould formed from a foundry sand comprising a blend of silica sand and a zircon aggregate, the zircon aggregate exhibiting a sharp rise in linear thermal expansion coefficient in a temperature band above 1200 C. and up to 1600 C.; and cooling the mould and molten metal to solidify the molten metal and form a cast article, wherein one or more surfaces of the mould, or of a portion of the mould, in contact with the molten metal are uncoated.

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 method of fabricating a casting is provided. The method includes creating a mixture of ceramic powder and a binder, pouring the mixture around sacrificial patterns, executing a first thermal treatment to set the mixture into a solid mold without damaging the sacrificial patterns, executing a second thermal treatment to remove the sacrificial patterns without removing any of the binder from the solid mold, executing at least one of a third thermal treatment and a chemical treatment to remove a quantity of the binder to transform the solid mold into a solid breakaway mold and pouring molten metallic material into the solid breakaway mold.

A method of fabricating a casting is provided. The method includes creating a mixture of ceramic powder and a binder, pouring the mixture around sacrificial patterns, executing a first thermal treatment to set the mixture into a solid mold without damaging the sacrificial patterns, executing a second thermal treatment to remove the sacrificial patterns without removing any of the binder from the solid mold, executing at least one of a third thermal treatment and a chemical treatment to remove a quantity of the binder to transform the solid mold into a solid breakaway mold and pouring molten metallic material into the solid breakaway mold.

A sand additive for use in a no bake foundry mix composition having a polyurethane-based binder system reduces the amount of smoke emitted when molds and cores formed from the composition are exposed to molten metal, as compared to when the sand additive is not used. The sand additive comprises yellow iron oxide having the chemical formula Fe(OH).sub.3. It can also comprise at least one of red iron oxide, black iron oxide and wstite. In such cases, the yellow iron oxide accounts for about 10 to about 40 weight percent of the combined weight of the yellow iron oxide, red iron oxide, black iron oxide and wstite, and preferably, about 20 to about 30 weight percent of the combined weight of the yellow iron oxide, red iron oxide, black iron oxide and wstite.

A sand additive for use in a no bake foundry mix composition having a polyurethane-based binder system reduces the amount of smoke emitted when molds and cores formed from the composition are exposed to molten metal, as compared to when the sand additive is not used. The sand additive comprises yellow iron oxide having the chemical formula Fe(OH).sub.3. It can also comprise at least one of red iron oxide, black iron oxide and wstite. In such cases, the yellow iron oxide accounts for about 10 to about 40 weight percent of the combined weight of the yellow iron oxide, red iron oxide, black iron oxide and wstite, and preferably, about 20 to about 30 weight percent of the combined weight of the yellow iron oxide, red iron oxide, black iron oxide and wstite.

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.