Ceramic, multilayer graphite mold and method of fabrication

Claim 1

IN THE METHOD OF PRODUCING A MOLD ABOUT A DISPOSABLE PATTERN WHICH IS REMOVED TO DEFINE THE MOLD CAVITY AND IN WHICH THE MOLD IS ADAPTED FOR USE IN THE CASTING OF METALS OF THE GROUP IV-B IN THE PERIODIC SYSTEM, THE STEPS OF WETTING THE SURFACES OF THE PATTERN WITH AN AQUEOUS DIP COAT COMPOSITION THE SOLIDS OF WHICH CONSIST ESSENTIALLY OF GRAPHITE FLOUR, COLLOIDAL GRAPHITE AND AN ORGANIC HIGH MOLECULAR WEIGHT MATERIAL WHICH IS THERMALLY DECOMPOSABLE AT ELEVATED TEMPERATURE AND IN A NON-OXIDIZING ATMOSPHERE TO A STABLE FORM OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF CARBON AND A CARBONCEOUS MATERIAL IN WHICH THE GRAPHITE FLOUR IS PRESENT IN AN AMOUNT WITHIN THE RANGE OF 15-45 PERCENT BY WEIGHT, THE COLLOIDAL GRAPHITE IS PRESENT IN AN AMOUNT UP TO 5 PERCENT BY WEIGHT AND THE ORGANIC HIGH MOLECULAR WEIGHT MATERIAL IS PRESENT IN AN AMOUNT WITHIN THE RANGE OF 7-30 PERCENT BY WEIGHT, COVERING THE SURFACES OF THE PATTERN WET WITH THE DIP COAT COMPOSITION WITH A GRAPHITE STUCCO, REPEATING THE APPLICATION OF DIP COAT COMPOSITION AND STUCCO FOR A NUMBER OF CYCLES WITH INTERMEDIATE DRYING TO BUILD UP A WALL THICKNESS ABOUT THE PATTERN FORMING AT LEAST A PART OF THE MOLD WALL, REMOVING THE PATTERN AND FIRING THE MOLD TO A TEMPERATURE IN EXCESS OF 800*F. IN A NON-OXIDIZING ATMOSPHERE TO CURE THE MOLD AND THERMALLY TO REDUCE THE ORGANIC HIGH MOLECULAR WEIGHT MATERIAL TO THE CARBONACEOUS REDUCTION REACTION PRODUCT IN SITU IN THE WALLS OF THE MOLD TO PRODUCE A MOLD IN WHICH THE WALL PORTIONS ABOUT THE MOLD CAVITY ARE RELATIVELY IMPERVIOUS TO MOLTEN METAL BUT WHICH ENABLES VAPORS TO PASS THERETHROUGH.