CASTINGS OF METALLIC ALLOYS FABRICATED IN ANISOTROPIC PYROLYTIC GRAPHITE MOLDS UNDER VACUUM

摘要

Molds 10 are fabricated having a substrate 14 of high density, high strength ultrafine grained isotropic graphite, and having a mold cavity 16 coated with pyrolytic graphite 18. The molds may be made by making the substrate main body of high density, high strength ultrafine grained isotropic graphite, by, for example, isostatic or vibrational molding, machining the substrate to form the mold cavity, and coating the mold cavity with pyrolytic graphite via a chemical deposition process. The molds may be used to make various metallic alloys such as nickel, cobalt and iron based superalloys, stainless steel alloys, titanium alloys and titanium aluminide alloys into engineering components by melting the alloys in a vacuum or under a low partial pressure of inert gas and subsequently casting the melt in the graphite molds under vacuum or low partial pressure of inert gas.