Coating compositions for casting moulds and cores for avoiding maculate surfaces

Abstract

The invention relates to a size composition (coating composition) for casting moulds and cores, comprising at least one metal additive which contains a metal or a compound of a metal, wherein the metal is selected from one of groups 7 or 9 to 12 of the Periodic Table of the Elements. The invention also relates to a process for producing a casting mould, which comprises a mould coating of the size (coating) according to the invention, and to the use of said mould for the casting of metals.

1 . Coating composition for casting moulds and cores comprising at least one carrier liquid and a metal additive that comprises a metal or a compound of a metal, wherein the metal is selected from the group of manganese and copper, and wherein the fraction of the metal additive is less than 50 wt. % based on the solid content of the coating composition. 
     
     
         2 . Coating composition according to  claim 1 , wherein the metal is manganese or the compound of a metal comprising manganese. 
     
     
         3 . Coating composition according to either  claim 1 , wherein the metal is employed in pure form or in the form of an alloy with other metals. 
     
     
         4 . Coating composition according to  claim 1 , wherein the metal or metal compound is contained in the metal additive in a fraction of at least 10 wt. %, determined as metal and based on the weight of the metal additive. 
     
     
         5 . Coating composition according to  claim 1 , wherein the metal additive is contained in the coating composition in a fraction of at least 10 wt. % based on the solid fraction of the coating composition. 
     
     
         6 . Coating composition according to  claim 1 , wherein the metal is contained in the metal additive in the form of an iron alloy. 
     
     
         7 . Coating composition according to  claim 1 , wherein the metal additive has a mean particle size (D50) in the range from 0.5 to 5000 μm. 
     
     
         8 . Coating composition according to  claim 1 , wherein the coating composition contains a solvent and the solvent is formed, at least in part, of at least one alcohol. 
     
     
         9 . Coating composition according to  claim 8 , wherein the at least one alcohol forms a fraction of at least 50 wt. % in the solvent. 
     
     
         10 . A method for producing a casting mould, wherein a mould material mixture is provided that contains at least one refractory mould material and a binder, the mould material mixture is shaped to a basic mould comprising a mould cavity, and at least the faces of the mould cavity of the basic mould are coated with a coating composition according to  claim 1 . 
     
     
         11 . A casting mould with a mould cavity, wherein at least the faces of the mould cavity are coated with a coating according to  claim 1 . 
     
     
         12 . Use of a casting mould according to  claim 11  for metal casting. 
     
     
         13 . The use according to  claim 12 , wherein the metal casting is an iron casting or a steel casting. 
     
     
         14 . The coating composition according to  claim 1 , wherein the fraction of the metal additive in the coating composition is less than 40 wt. %, based on the solid content of the coating composition. 
     
     
         15 . The coating composition according to  claim 1 , wherein the composition further contains a binder. 
     
     
         16 . The coating composition according to  claim 1 , wherein the fraction of the metal additive in the coating composition is less than 35 wt. % based on the solid content of the coating composition.