Precision casting mold and method of producing the same

Abstract

Provided is a precision casting mold including a core having a shape corresponding to an internal hollow portion of a cast product and an outer mold corresponding to a shape of an outer peripheral surface of the cast product, and the outer mold is made up of: a prime layer which is formed on an inner peripheral surface and is a slurry film obtained by drying slurry for the precision casting mold which includes mono-dispersed ultrafine alumina particles and silica sol having a particle size of 1.0 μm or smaller and functions as mullite during firing; and a multi-layered backup layer which is formed on the outside of the prime layer by repeatedly forming a first backup layer obtained by forming and drying a slurry layer formed from the slurry for the precision casting mold and a stucco layer in which a stucco material is adhered to the slurry layer.

1 . A precision casting mold which is used to produce a cast product, comprising:
 a core having a shape corresponding to an internal hollow portion of the cast product; and   an outer mold corresponding to a shape of an outer peripheral surface of the cast product,   wherein the outer mold is made up of: a prime layer which is formed on an inner peripheral surface and is formed from a slurry film obtained by drying slurry for the precision casting mold which includes mono-dispersed ultrafine alumina particles and silica sol having a particle size of 0.3 μm to 0.6 μm and functions as mullite during firing; and a multi-layered backup layer which is formed on the outside of the prime layer by repeatedly forming a backup layer obtained by forming and drying a slurry layer formed from the slurry for the precision casting mold and a stucco layer in which a stucco material is adhered to the slurry layer.   
     
     
         2 . The precision casting mold according to  claim 1 , wherein the slurry for the precision casting mold contains either of zircon powders or alumina powders having an average particle size of 50 μm or smaller, and
 the stucco material is either of zircon stucco particles or alumina stucco particles having an average particle size of 0.5 mm or larger. 
 
     
     
         3 . The precision casting mold according to  claim 1 , wherein the prime layer has the stucco layer in which the stucco material is adhered to the slurry layer formed from the slurry for the precision casting mold. 
     
     
         4 . A method of producing a precision casting mold which is used to produce a cast product, the method comprising:
 a first film forming process in which a precision casting wax pattern is immersed and pulled up into/from slurry for the precision casting mold which includes mono-dispersed ultrafine alumina particles and silica sol having a particle size of 0.3 μm to 0.6 μm and functions as mullite during firing and then a drying treatment is performed, thereby forming a prime layer, which is formed from a slurry film, on a surface of the wax pattern;   a second film forming process in which a stucco material is sprinkled on a surface of the slurry after the wax pattern formed with the prime layer is immersed and pulled up into/from the slurry for the precision casting mold and then a drying treatment is performed, thereby forming a backup layer;   a molded body forming process in which the second film forming process of forming the backup layer is repeated more than once, thereby obtaining a molded body formed with a multi-layered backup layer;   a wax removing process in which wax of the wax pattern is melted and removed from the obtained molded body; and   a mold firing process in which the molded body obtained after the wax removal is subjected to a firing treatment, thereby obtaining a mold.   
     
     
         5 . The method of producing the precision casting mold according to  claim 4 , wherein a stucco material is adhered to the slurry layer formed from the slurry for the precision casting mold to form a stucco layer and the stucco layer is dried during the first film forming process. 
     
     
         6 . The method of producing the precision casting mold according to  claim 4 , wherein a dispersing agent of the slurry for the precision casting mold is polycarboxylic acid salts. 
     
     
         7 . The precision casting mold according to  claim 1 , wherein a mixing ratio of the alumina particles and the silica sol (Al 2 O 3 /SiO 2 ) is equal to 1.5 (molar ratio). 
     
     
         8 . The precision casting mold according to  claim 4 , wherein a mixing ratio of the alumina particles and the silica sol (Al 2 O 3 /SiO 2 ) is equal to 1.5 (molar ratio).