A no bake process is provided for preparing a foundry shape. A major amount of an appropriate foundry aggregate, especially a sand that has been mechanically-reclaimed, is mixed with an amount of halloysite tubes. A binder system, especially a water-based binder, such as an aqueous alkaline phenolic resole resin, is added to the mixed aggregate and halloysite, and a liquid co-reactant for curing the binder is also added. By intimately mixing the components, a foundry molding compound is formed and it can be placed into a mold or patter to cure into a foundry shape. When removed from the mold or pattern, the foundry shape can be used to cast molten metal.

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 method to form a displacement, the method including disposing a powder blend comprising a plurality of ground ceramic particles and a plurality of ground resin particles into a mold, densifying the powder blend while in the mold, heating the mold to form a first displacement, impregnating said first displacement with a polymer precursor compound to form a second displacement, and heating the second displacement to form a third displacement.

A method to form a displacement, the method including disposing a powder blend comprising a plurality of ground ceramic particles and a plurality of ground resin particles into a mold, densifying the powder blend while in the mold, heating the mold to form a first displacement, impregnating said first displacement with a polymer precursor compound to form a second displacement, and heating the second displacement to form a third displacement.

The present invention provides a curing agent for casting a water glass, including an ester and an amorphous silicon dioxide obtained by a thermal decomposition of ZrSiO.sub.4; and the curing agent for casting the water glass does not contain water. According to the present invention, the curing agent for casting the water glass has a strong adhesion-enhancing effect and a long shelf life, and is easy to use.

The present invention provides a curing agent for casting a water glass, including an ester and an amorphous silicon dioxide obtained by a thermal decomposition of ZrSiO.sub.4; and the curing agent for casting the water glass does not contain water. According to the present invention, the curing agent for casting the water glass has a strong adhesion-enhancing effect and a long shelf life, and is easy to use.

Sand for a casting mold including sand, a binder, and an inorganic compound particle having poor water solubility and generating a gas, which is at least one of water vapor or carbon dioxide gas, by heat from a molten metal.

Sand for a casting mold including sand, a binder, and an inorganic compound particle having poor water solubility and generating a gas, which is at least one of water vapor or carbon dioxide gas, by heat from a molten metal.

The invention relates to a casting core for casting moulds, wherein the casting core comprises a central core and a core shroud arranged around the central core. The core shroud contains or consists of ceramic particles bound to a binder. The central core contains or consists of ceramic particles bound to a binder, wherein the ceramic particles of the central core contain or consist of at least one component, which exhibits, at a temperature in a range from 100° C. to 1500° C., a thermally induced phase transformation, and/or at least two components, the thermal expansion coefficients of which at 20° C. differ by at least 5.Math.10−6 K−1. The invention further relates to a method for producing the casting core according to the invention and the use of the casting core according to the invention.