Molding of refractory materials

Claim 2

IN A PROCESS OF FABRICATING SHAPED STRUCTURES OF A REFRACTORY MATERIAL HAVING A PARTICLE SIZE UP TO 1 MM., AND SELECTED FROM THE GROUP CONSISTING OF SILICON CARBIDE, SILICON NITRIDE, BORON CARBIDE, BORON NITRIDE, ALUMINUM NITRIDE, AND ALUMINUM BORIDE COMPRISING THE STEPS OF MIXING THE REFRACTORY MATERIAL WITH A BINDER, FORMING THE MIXTURE INTO A SHAPED STRUCTURE, AND SINTERING SAID SHAPED STRUCTURE AT ELEVATED TEMPERATURES, THE IMPROVEMENT COMPRISING EMPLOYING AS THE BINDER ABOUT 1-10% BY VOLUME OF THE TOTAL MIXTURE, OF GAMMA ALUMINUM OXIDE HAVING A PARTICLE SIZE OF 5-50.10-6 MM. AND 0.01-5% BY VOLUME OF THE TOTAL MIXTURE, OF ALUMINUM HAVING A PARTICLE SIZE OF 10-3-10-1 MM., AND CONDUCTING SAID SINTERING STEP AT A TEMPERATURE OF AT LEAST 1400*C. IN AN ATMOSPHERE INERT TO SAID REFRACTORY MATERIAL.