Cold molded dense silicon carbide articles and method of making the same

Claim 1

A DENSE ARTICLE OF MANUFACTURE COMPOSED SUBSTANTIALLY ENTIRELY OF SELF-BONDED SILICON CARBIDE, HAVING A DENSITY OF AT LEAST 3.00 AND CONTAINING IN ADDITION TO SILICON CARBIDE, AN OCCLUDED SMALL QUANTITY OF FREE SILICON NOT AMOUNTING TO MORE THAN 5 PERCENT BY WEIGHT OF SAID ARTICLE, AND MADE BY A PROCESS COMPRISING THE SEPARATE STEPS OF COLD PRESSING A POROUS MASS CONSISTING ESSENTIALLY OF GRANULAR SILICON CARBIDE INTO A SHAPE, THEN INTRODUCING A CONTROLLED AMOUNT OF CARBON INTO THE PORES OF THE SHAPED MASS, SAID CONTROLLED AMOUNT OF CARBON BEING BETWEEN 85 PERCENT AND 95 PERCENT OF THE STOICHIOMETRIC AMOUNT THAT IS REQUIRED TO REACT WITH SILICON TO FORM SUFFICIENT SILICON CARBIDE TO FILL THE PORES AND FORM A SOLID NON-POROUS BODY OF SILICON CARBIDE, AND THEN HEATING SAID SHAPED MASS TO A TEMPERATURE OF AT LEAST 2000*C. IN A SILICON SUPPLYING ENVIRONMENT ESSENTIALLY FREE OF SILICA TO CAUSE THE SILICON TO ENTER THE PORES OF THE SHAPED MASS AND REACT WITH THE INTRODUCED CABON TO FORM SILICON CARBIDE AND THEREAFTER MAINTAINING THE BODY AT A TEMPERATURE OF ABOUT 2100*C. TO 2300*C. FOR SUFFICIENT TIME TO CAUSE THE SILICON CARBIDE SO FORMED TO GO TO THE HEXAGONAL CRYSTALLINE FORM.

Claim 3

A METHOD OF MAKING A HIGH DENSITY SILICON CARBIDE ARTICLE OF MANUFACTURE HAVING A DENSITY OF AT LEAST 3.00, WHICH COMPRISES THE SEPARATE STEPS OF COLD PRESSING A POROUS MASS CONSISTING ESSENTIALLY OF GRANULAR SILICON CARBIDE INTO A SHAPE, THEN INTRODUCING A CONTROLLED AMOUNT OF CARBON INTO THE PORES OF THE SHAPED MASS, AND THEN HEATING THE SHAPED MASS IN A SILICON SUPPLYING ENVIRONMENT THAT IS ESSENTIALLY FREE OF SILICA TO CAUSE THE SILICON TO ENTER THE PORES OF THE SHAPED MASS AND REACT WITH THE INTRODUCED CARBON TO FORM SILICON CARBIDE.

Claim 4

A METHOD OF MAKING A HIGH DENSITY SILICON CARBIDE ARTICLE OF MANUFACTURE HAVING A DENSITY OF AT LEAST 3.00, WHICH COMPRISES THE SEPARATE STEPS OF COLD PRESSING A POROUS MASS CONSISTING ESSENTIALLY OF GRANULAR SILICON CARBIDE INTO A SHAPE, THEN INTRODUCING A CONTROLLED AMOUNT OF CARBON INTO THE PORES OF THE SHAPED MASS, AND THEN HEATING THE SHAPED MASS IN A SILICON SUPPLYING ENVIRONMENT THAT IS ESSENTIALLY FREE OF SILICA TO CAUSE THE SILICON TO ENTER THE PORES OF THE SHAPED MASS AND REACT WITH THE INTRODUCED CARBON TO FORM SILICON CARBIDE.