Coating compositions for inorganic casting molds and cores, containing salts, and use thereof

Abstract

The subject matter of the invention relates to sizing compositions as coating compositions for casting molds. The sizing composition is suitable for cores and molds, in particular those produced using water glass as a binder. The sizing composition contains certain salts.

1 . A sizing composition comprising:
 (A) salts of at least one of the metals magnesium and manganese, the salts present in a concentration, of greater than 1% by weight, based on the sizing composition,   (B) a carrier fluid comprising or consisting of water, and   (C) refractory materials.   
     
     
         2 . The sizing composition according to  claim 1 , wherein the salts have as an anion at least one of: sulfate ion(s) and chloride ions. 
     
     
         3 . The sizing composition according to  claim 1 , wherein manganese is used in the +2 or +4 oxidation state and magnesium is used in the +2 oxidation state. 
     
     
         4 . The sizing composition according to  claim 1 , wherein the concentration of the salts is greater than 3% by weight based on the sizing agent composition. 
     
     
         5 . The sizing composition according to  claim 1 , wherein the salt concentration corresponds, at maximum, to the saturation concentration of the salt in the carrier fluid used. 
     
     
         6 . The sizing composition according to  claim 1 , wherein the concentration of the salts is less than 10% by weight, based on the sizing composition. 
     
     
         7 . The sizing composition according to  claim 1 , wherein the carrier liquid comprises more than 50% water. 
     
     
         8 . The sizing composition according to  claim 1 , wherein the solids content of the sizing composition amounts to 30 to 70% by weight. 
     
     
         9 . The sizing composition according to  claim 1 , wherein the sizing composition comprises 10 to 85% by weight of refractory materials, based on the solids content of the sizing composition. 
     
     
         10 . The sizing composition according to  claim 1 , wherein the refractory materials are selected from the group consisting of: quartz, aluminum oxide, zirconium dioxide, aluminum silicates, zirconium sands, zirconium silicates, olivine, talc, mica, coke, feldspar, diatomite, calcined kaolins, kaolinite, metakaolinite, iron oxide, bauxite and mixtures thereof. 
     
     
         11 . The sizing composition according to  claim 10 , in which the refractory materials have particle sizes of 0.1 to 500 μm, measured by light scattering according to DIN/ISO 13320. 
     
     
         12 . The sizing composition according to  claim 1 , wherein the sizing composition comprises 0.1 to 20% by weight, of at least one binder, based on the solids content of the sizing composition. 
     
     
         13 . The sizing composition according to  claim 1 , wherein the sizing composition comprises a lustrous coal forming agent or graphite. 
     
     
         14 - 17 . (canceled) 
     
     
         18 . The sizing composition according to  claim 1 , wherein the salts comprise at least one salt of both magnesium and manganese. 
     
     
         19 . The sizing composition according to  claim 1 , wherein the concentration of the salts is greater than 5% by weight based on the sizing agent composition. 
     
     
         20 . The sizing composition according to  claim 7 , wherein the carrier fluid further comprises alcohols, including polyalcohols and polyether alcohols. 
     
     
         21 . The sizing composition according to  claim 20 , wherein the carrier fluid can be fully evaporated at up to 160° C. and 1013 mbar. 
     
     
         22 . The sizing composition according to  claim 1 , in which the refractory materials have particle sizes of 1 to 200 μm, measured by light scattering according to DIN/ISO 13320. 
     
     
         23 . The sizing composition according to  claim 1 , wherein the sizing composition comprises 0.5 to 5% by weight, of at least one binder, based on the solids content of the sizing composition. 
     
     
         24 . The sizing composition according to  claim 13 , wherein the lustrous coal forming agent or graphite is present in the amount of 0.1 to 10% by weight. 
     
     
         25 . The sizing composition according to  claim 13 , wherein the lustrous coal forming agent or graphite is present in the amount of 0.5 to 3% by weight. 
     
     
         26 . A mold or core for casting, comprising:
 a molding material mixture, coated with a sizing composition according to  claim 1 ; and   a binder comprising water glass.   
     
     
         27 . The mold or core of  claim 26 , wherein:
 the molding material mixture comprises at least one member selected from the group consisting of: silicon dioxide, aluminum oxide, titanium oxide and zinc oxide.   
     
     
         28 . The mold or core of  claim 26 , wherein:
 the sizing composition is diluted with at least water before coating the molding material mixture.   
     
     
         29 . A method for sizing a mold or core for casting, comprising the steps of:
 providing a mold or core for casting, the mold or core comprising a molding material mixture and a binder comprising water glass; and   coating the mold or core with a sizing composition comprising:
 salts of at least one of the metals magnesium and manganese, the salts present in a concentration, of greater than 1% by weight, based on the sizing composition; 
 a carrier fluid comprising water, and 
 refractory materials. 
   
     
     
         30 . The method of  claim 29 , wherein:
 the molding material mixture comprises at least one member selected from the group consisting of: silicon dioxide, aluminum oxide, titanium oxide and zinc oxide.   
     
     
         31 . The method of  claim 29 , wherein:
 the sizing composition is diluted with at least water before the coating step.