Core composition for casting, and method for preparing core for casting using the same

Abstract

Disclosed are a core composition for casting and a method for preparing a core for casting using the composition. The core composition for casting includes: molding sand; a binder that includes a water glass-based binder and an oxide film inhibitor; and an additive, thereby improving a sand removing property without releasing harmful gases.

1 . A core composition for casting, comprising:
 molding sand;   a binder that includes a water glass-based binder and an oxide inhibitor; and   an additive.   
     
     
         2 . The core composition of  claim 1 , wherein the oxide film inhibitor includes sodium hexametaphosphate, sodium pyrophosphate, or a combination thereof. 
     
     
         3 . The core composition of  claim 2 , wherein the oxide film inhibitor is included in an amount of about 0.1 to 0.3% by weight with respect to the total weight of the core composition. 
     
     
         4 . The core composition of  claim 1 , wherein the additive for sand removal is formed with zinc oxide powder, 
     
     
         5 . The core composition of  claim 4 , wherein the additive for sand removal is included in an amount of about 0.4 to 0.6% by weight with respect to the total weight of the core composition. 
     
     
         6 . The core composition of  claim 1 , wherein the binder is included in an amount of about 4 to 6 parts by weight with respect to 100 parts by weight of the molding sand 
     
     
         7 . The core composition of  claim 6 , wherein the water glass-based binder includes an amount of about 8 to 10 parts by weight of Na 2 O and an amount of about 25 to 30 parts by weight of SiO 2  with respect to 100 parts by weight of the binder for a core. 
     
     
         8 . The core composition of  claim 7 , wherein a molar ratio of the SiO 2 :Na 2 O ranges from about 1:3.0 to about 1:3.3. 
     
     
         9 . A core composition for casting, consisting essentially of:
 mold sand;   a binder in amount of about 4 to 6 parts by weight with respect to 100 parts by weight of the molding sand, the binder consisting essentially of an amount of about 8 to 10 parts by weight of Na 2 O and about 25 to 30 parts by weight of SiO 2  with respect to 100 parts by weight of the binder and a oxide film in amount of about 0.1 to 0.3% by weight with respect to the total weight of the core composition; and   a zinc oxide powder in an amount of about 0.4 to 0.6% by weight with respect to the total weight of the core composition.   
     
     
         10 . A method for preparing a core for casting, comprising:
 preparing a mixture by mixing components of a core composition for casting, the composition comprises: molding sand, a binder that includes a water glass-based binder and an oxide film inhibitor and an additive;   supplying the mixture to a core mold; and   dehydrating the binder by supplying heat and hot air to the core mold supplied with the mixture.   
     
     
         11 . The method of  claim 10 , wherein the heat is applied at a temperature range of about 150 to 180° C., and the hot air is supplied at a temperature range of about 170 to 190° C. 
     
     
         12 . The method of  claim 10 , wherein the oxide film inhibitor includes sodium hexametaphosphate, sodium pyrophosphate, or a combination thereof. 
     
     
         13 . The method of  claim 12 , wherein the oxide film inhibitor is included in an amount of about 0.1 to 0.3% by weight with respect to the total weight of the core composition. 
     
     
         14 . The method of  claim 10 , wherein the additive for sand removal is formed with zinc oxide powder. 
     
     
         15 . The method of  claim 14 , wherein the additive for sand removal is included in an amount of about 0.4 to 0.6% by weight with respect to the total weight of the core composition. 
     
     
         16 . The method of  claim 10 , wherein the binder is included in an amount of about 4 to 6 parts by weight with respect to 100 parts by weight of the molding sand. 
     
     
         17 . The method of  claim 10 , wherein the water glass-based binder includes an amount of about 8 to 10 parts by weight of Na 2 O and an amount of about 25 to 30 parts by weight of SiO 2  with respect to 100 parts by weight of the binder for a core. 
     
     
         18 . The method of  claim 17 , wherein a molar ratio of the SiO 2 :Na 2 O ranges from about 1:3.0 to 1:3.3. 
     
     
         19 . A casting product obtained using a core composition of  claim 1 . 
     
     
         20 . A casting product obtained from a method of  claim 10 .