Method for coating graphite with niobium carbide

Claim 1

IN A PROCESS FOR REACTING GRAPHITE WITH FINELY DIVIDED NIOBIUM METAL TO PRODUCE A SOLID METAL CARBIDE COATING COMPRISING THE STEPS OF CONTACTING NIOBIUM METAL POWDERS RANDOMLY WITH A QUANTITY OFGRAPHITE, SAID QUANTITY BEING SUFFICIENT TO COVER THE FRAPHITE SURFACE UPON MELTING AND SPREADING, SAID DISTANCE BETWEENSAID PARTICLES NOT EXCEEDNG ONE INCH, DEGASSING SAID METAL AND SAID GRAPHITE SURFACES BY APPLYING A VACUUM PRESSURE LOWER THAN ABOUT 10-3 MM. HG THERETO WHILE HEATING SAID METAL AND GRAPHITE TO A TEMPERATURE OF AT LEAST 1400* C. FOR A PERIOD OF AT LEAST TEN MINUTES, FURTHER HEATING SAID METAL AND SAID GRAPHITE TO A TEMPER<ATURE OF ABOVE ABOUT 2500*C. WITHIN A PERIOD OF ABOUT 15 MINUTES WHILE CONTINUING TO PUMP THEREON AT A PUMPING RATE IN THE RANGE OF ABOUT 50 LITERS PER SECOND PER SQUARE INCH OF GRAPHITE SURFACE, SAID VACUUM PRESSURE BEING MAINTAINED BETWEEN 10-3 AND 10-4 MM. HG, WHEREBY SAID NIOBIUM POWDERS MELT, FLOW AND WET SAID GRAPHITE SURFACES, AND CONTINUING TO HEAT SAID GRAPHITE-NIOBIUM COMBINATION UNTIL CARBURIZATION TAKES PLACE.