The invention relates to molding material mixtures containing a molding base material, water glass, amorphous silicon dioxide and an oxidic boron compound, and the production of molds and cores, in particular for metal casting.

The invention relates to molding material mixtures containing a molding base material, water glass, amorphous silicon dioxide and an oxidic boron compound, and the production of molds and cores, in particular for metal casting.

A molding material mixture for producing casting molds for metal processing, particularly for non-ferrous metals, such as aluminum or magnesium, is intended to reduce problems such as metal-mold reaction and/or shrinkage porosity defect. The free-flowing refractory molding material in the molding material mixture is coated with a mixture of inorganic salts exhibiting a eutectic melting point in the range of about 400 C to about 500 C, particularly in the range of about 420 C to about 460 C. Preferably this coating occurs by contacting the inorganic salt mixture with the molding material mixture at a temperature between 500 C and 700 C, in a manner that maintains the free-flowing nature of the coated product. One mixture of inorganic salts that is used is a mixture consisting of, by weight: 74% potassium fluoroborate; 15% potassium chloride; and 12% potassium fluoride. This mixture has a eutectic melting point of 420 C.

The additive composition of the present invention is one blended in a sand composition which is subjected to foaming to mold a sand mold, and includes (A) an alkylsulfonate metal salt having an alkyl group with 9 to 22 carbon atoms. The additive composition may further include at least one component selected from a group consisting of (B) an alkylsulfate metal salt, (C) a polyoxyalkylene alkyl ether sulfate metal salt, and (D) an alkylbenzene sulfonate metal salt.

The additive composition of the present invention is one blended in a sand composition which is subjected to foaming to mold a sand mold, and includes (A) an alkylsulfonate metal salt having an alkyl group with 9 to 22 carbon atoms. The additive composition may further include at least one component selected from a group consisting of (B) an alkylsulfate metal salt, (C) a polyoxyalkylene alkyl ether sulfate metal salt, and (D) an alkylbenzene sulfonate metal salt.

Feeders for use in the foundry industry comprising (a) rice husk ash containing, based on the total amount of the constituents detectable in the rice husk ash by quantitative phase analysis by means of x-ray diffractometry (i) crystalline modifications of silicon dioxide, (ii) monoclinic feldspar and (iii) amorphous silicon dioxide, a total content of at least 70 wt. %, preferably more than 75 wt. % of (i) crystalline modifications of silicon dioxide and (ii) monoclinic feldspar, wherein, based on the total weight of the shapeable composition of the feeder, the amount of this rice husk ash is in the range of from 5 to 50 wt. %, preferably 5 to 25 wt. %, (b) cured binder, (c) optionally fiber material, (d) optionally one or more further fillers, and (e) optionally an oxidizable metal and an oxidizing agent for the oxidizable metal are described.

Feeders for use in the foundry industry comprising (a) rice husk ash containing, based on the total amount of the constituents detectable in the rice husk ash by quantitative phase analysis by means of x-ray diffractometry (i) crystalline modifications of silicon dioxide, (ii) monoclinic feldspar and (iii) amorphous silicon dioxide, a total content of at least 70 wt. %, preferably more than 75 wt. % of (i) crystalline modifications of silicon dioxide and (ii) monoclinic feldspar, wherein, based on the total weight of the shapeable composition of the feeder, the amount of this rice husk ash is in the range of from 5 to 50 wt. %, preferably 5 to 25 wt. %, (b) cured binder, (c) optionally fiber material, (d) optionally one or more further fillers, and (e) optionally an oxidizable metal and an oxidizing agent for the oxidizable metal are described.

The present invention relates to the use of closed-pore microspheres of expanded perlite as a filler for producing moldings for the foundry industry, to a composition for producing moldings for the foundry industry, comprising closed-pore microspheres of expanded perlite as a filler, and a binder, the binder being selected from the group consisting of water glass, phenol-formaldehyde resins, two-component systems comprising as reactants a polyisocyanate and a polyol component containing free hydroxyl groups (OH groups), and starch, and also to moldings for the foundry industry and to a process for producing a molding for the foundry industry.

The present invention relates to the use of closed-pore microspheres of expanded perlite as a filler for producing moldings for the foundry industry, to a composition for producing moldings for the foundry industry, comprising closed-pore microspheres of expanded perlite as a filler, and a binder, the binder being selected from the group consisting of water glass, phenol-formaldehyde resins, two-component systems comprising as reactants a polyisocyanate and a polyol component containing free hydroxyl groups (OH groups), and starch, and also to moldings for the foundry industry and to a process for producing a molding for the foundry industry.

The present invention discloses a mold core assembly. The mold core assembly includes at least one core. The core comprises a main body member and a high temperature-resistant material with a melting point over 1500 C., the length-diameter ratio of the main body member is greater than 50, and the main body member includes a high melting point metal with a melting point over 1500 C. The mold core assembly also includes a shell mold, wherein the shell mold encloses the core to form a cavity between the shell mold and the core, so as to accommodate a molten casting metal. The present invention further discloses an investment casting method.