Precision-casting core, precision-casting core manufacturing method, and precision-casting mold

Abstract

A precision-casting core body is formed by mixing and sintering silica particles and silica fume. The resistance of the mixture of silica fume decreases during heating injection molding, and hence the fluidity is improved by the addition of silica fume. As a result, since the fluidity is improved, it is possible to decrease an injection molding pressure when a core is manufactured. Further, the mixture can be applied to a thin compact and a complex compact with improved fluidity.

1 . A precision-casting core in which a precision-casting core body is formed by mixing and sintering silica particles of silica sand of 20 to 70 μm and silica fume of 5 wt % to 30 wt % as additive amount. 
     
     
         2 . The precision-casting core according to  claim 1 ,
 wherein a coating layer is formed on the surface of the sintered precision-casting core body.   
     
     
         3 . A precision-casting mold used to manufacture a cast metal, comprising:
 a precision-casting core in which a precision-casting core body is formed by mixing and sintering silica particles of silica sand of 20 to 70 μm and silica fume of 5 wt % to 30 wt % as additive amount having a shape corresponding to a cavity inside the cast metal; and   an outer mold corresponding to the shape of the outer peripheral surface of the cast metal.   
     
     
         4 . A precision-casting core manufacturing method comprising:
 immersing a sintered body of a precision-casting core body mainly including silica particles of silica sand of 20 to 70 μm into a coating material including a silica material and an alumina material;   drying the sintered body; and   heating the sintered body so as to form a coating layer on the surface of the precision-casting core body.   
     
     
         5 . The precision-casting core manufacturing method according to  claim 4 ,
 wherein the silica material is silica sol and the alumina material is alumina sol.   
     
     
         6 . The precision-casting mold according to  claim 3 ,
 wherein a coating layer is formed on the surface of the sintered precision-casting core body.   
     
     
         7 . The precision-casting core according to  claim 2 ,
 wherein silica sol and silica fume are used as a material forming the coating layer.   
     
     
         8 . The precision-casting core according to  claim 2 ,
 wherein an alkoxide material is used as a material forming the coating layer.   
     
     
         9 . The precision-casting core according to  claim 2 ,
 wherein an alkoxide-silica fume material are used as a material forming the coating layer.   
     
     
         10 . The precision-casting mold according to  claim 6 ,
 wherein silica sol and silica fume are used as a material forming the coating layer.   
     
     
         11 . The precision-casting mold according to  claim 6 ,
 wherein an alkoxide material is used as a material forming the coating layer.   
     
     
         12 . The precision-casting mold according to  claim 6 ,
 wherein an alkoxide-silica fume material are used as a material forming the coating layer.