| abstract |
A PROCESS FOR FABRICATING LOW POROSITY, ESSENTIALLY DEFECT FREE, COMPOSITE REFRACTORY SHAPES OF NOVEL COMPOSITION. A POWDERED REFRACTORY MATERIAL IS MIXED WITH A CARBON CONTAINING SUBSTANCE AND THE MIXTURE IS COLD FORMED INTO A DESIRED SHAPE, THE PREFORMED SHAPE IS THEN HEAT TREATED TO CONVERT THECARBON CONTAINING SUBSTANCE TO CARBON. A MOLTEN METAL BATH IS PREPARED, COMPRISED OF AT LEAST TWO METALS, AT LEAST ONE OF WHICH IS CAPABLE OF REACTING WITH THE CARBON IN THE PREFORMED SHAPE, AND THE COMBINATION OF WHICH RESULTS IN A METALLIC MIXTURE GREATER THAN THAT OF THE REFRACTORY MATERIAL MAING UP THE MATRIX OF THE PREFORMED SHAPE. THEPERFORM IS THEN HEATED AND IMPREGNATED WITH THE MOLTEN METAL WHICH RESULTS IN SINTERING OF THE REFRACTORY MATERIAL MATRIX, AND THE REACTION OF AT LEAST ONE OF THE METALS WITH THE CARBON CONTAINED IN THE INTERSTICES FORMED BY THE PARTICULATE REFRACTORY MATERIAL, TO FORM METAL CARBIDE(S) THEREIN. THE COMPOSITE SHAPE IS THEN REMOVED FROM THE MOLTEN METAL BATH AND COOLED. BECAUSE THE COEFFICIENT OF THERMAL EXPANSION OF THE MIXTURE OF METALS IS CLOSE TO OR SLIGHTLY GREATER THAN THAT OF THE REFRACTORY MATRIX, THE COMPOSITE SHAPE COOLS TO ROOM TEMPERATURE ESSENTIALLY FREE OF CRACKS AND RESIDUAL STRESS. |