Patent ID: 7475717

Claim:
A mold, comprising a porous layer having a three-dimensional porous structure on a surface of a cavity of a shell, said mold being manufactured by the method comprising the steps of: scattering and adhering combustible powdery particles around a wax mold, which is a lost pattern, to thereby form a layer of combustible powdery particles around thereof, wherein said powdery particles have a particle size of from about 0.5 mm to about 1.0 mm; coating a film of a ceramic precursor slurry around the wax mold having the layer of the powdery particles formed thereon; subjecting the wax mold coated with the slurry film to a heat treatment at 100 to 180° C., to thereby dewax only the wax mold without said combustible powdery particles burning and vanishing; and firing the slurry film, to thereby burn and vanish the powdery particles in the slurry film and form said three-dimensional porous structure on said surface of said shell, wherein said three-dimensional porous structure includes a plurality of layers of pores, each pore having a size of from about 0.5 mm to about 1.0 mm; and wherein said porous structure has a depth extending from an uppermost surface to a lowermost surface of said porous structure, said depth being about 2 mm, and wherein said pores are continuous in a direction of said depth with adjacent pores being partly continuous, wherein said continuity of said pores in said depth direction being a result of said burning and vanishing of said powdery particles which turn to gas and exit said porous structure.