Provided is casting sand including sand and a solid acid catalyst mixed with the sand.

Provided is casting sand including sand and a solid acid catalyst mixed with the sand.

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.

According to the invention, by setting the linear thermal expansion amount when a mold made of a molding sand is heated from a room temperature to 1000° C. to be not more than 0.9%, and the ratio (D/d) between the diameter of a slump (D) and the diameter of a slump cone (d) in a slump test of the molding sand having a hardening agent kneaded to be not less than 1.65, a molding sand preferable for use in a mold produced using the self-hardening type of three dimensional laminate molding sand mold, having low thermal expansibility preventing occurrence of a veining defect, and capable of forming a large and complicated shape can be obtained.

According to the invention, by setting the linear thermal expansion amount when a mold made of a molding sand is heated from a room temperature to 1000° C. to be not more than 0.9%, and the ratio (D/d) between the diameter of a slump (D) and the diameter of a slump cone (d) in a slump test of the molding sand having a hardening agent kneaded to be not less than 1.65, a molding sand preferable for use in a mold produced using the self-hardening type of three dimensional laminate molding sand mold, having low thermal expansibility preventing occurrence of a veining defect, and capable of forming a large and complicated shape can be obtained.

A surfactant composition for a formed sand including 80 to 99.8 mass % of a compound (A) represented by formula (1); 0.1 to 10 mass % of a compound (B) represented by formula (2); and 0.1 to 10 mass % of an amphoteric surfactant (C):

R.sup.1O-(EO).sub.n—SO.sub.3M.sup.1  (1)

wherein R.sup.1 represents a hydrocarbon group having 6 to 22 carbons, EO represents oxyethylene group, n is 1 to 10, and M.sup.1 represents an alkali metal, an alkaline earth metal, ammonium or an organic ammonium;

R.sup.2O—SO.sub.3M.sup.2  (2)

wherein R.sup.2 represents a hydrocarbon group having 6 to 22 carbons, and M.sup.2 represents an alkali metal, an alkaline earth metal, ammonium or an organic ammonium.

A surfactant composition for a formed sand including 80 to 99.8 mass % of a compound (A) represented by formula (1); 0.1 to 10 mass % of a compound (B) represented by formula (2); and 0.1 to 10 mass % of an amphoteric surfactant (C):

R.sup.1O-(EO).sub.n—SO.sub.3M.sup.1  (1)

wherein R.sup.1 represents a hydrocarbon group having 6 to 22 carbons, EO represents oxyethylene group, n is 1 to 10, and M.sup.1 represents an alkali metal, an alkaline earth metal, ammonium or an organic ammonium;

R.sup.2O—SO.sub.3M.sup.2  (2)

wherein R.sup.2 represents a hydrocarbon group having 6 to 22 carbons, and M.sup.2 represents an alkali metal, an alkaline earth metal, ammonium or an organic ammonium.

The invention relates to a composition for forming a casting mold, the composition containing heat-resistant inorganic particles; a waterglass-based binder; a surfactant; a silicon-containing compound; activated carbon powder and grain; and water; and the silicon-containing compound contains at least one of metal silicon and ferrosilicon.

The invention relates to a composition for forming a casting mold, the composition containing heat-resistant inorganic particles; a waterglass-based binder; a surfactant; a silicon-containing compound; activated carbon powder and grain; and water; and the silicon-containing compound contains at least one of metal silicon and ferrosilicon.

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.