Process for producing sintered metals with dispersed oxides

Claim 1

IN A PROCESS FOR PRODUCING A METAL OF THE GROUP CONSISTING OF IRON, COBALT AND NICKEL AND ALLOYS OF THESE METALS WITH EACH OTHER AND WITH OTHER METALS WHOSE OXIDES HAVE A FREE ENERGY OF FORMATION AT 27*C. OF FROM 30 TO 70 KILOCALORIES PER GRAM ATOM OF OXYGEN, SAID METAL HAVING IMPROVED PROPERTIES BY HAVING UNIFORMLY DISPERSED THEREIN A PLURALITY OF DISCRETE, SUBMICRON-SIZED PARTICLES OF A REFRACTORY OXIDE THE STEPS COMPRISING (A) PRECIPITATING A WATER-SOLUBLE, HYDROUS, OXYGEN-CONTAINING COMPOUND OF THE METAL TO BE IMPROVED, WHEREIN THE METAL IS IN AN OXIDIZED STATE, AS A COATING AROUND A PLURALITY SUBSTANTIALLY DISCRETE, SUBMICRON SIZED PARTICLES OF A METALOXYGEN COMPOUND WHICH, WHEN HEATED TO CONSTANT WEIGHT AT 1500*C., IS A REFRACTORY OXIDE HAVING A MELTING POINT ABOVE 1000*C. AND A FREE ENERGY OF FORMATION AT 1000* C. ABOVE 60 KILOGRAM CALORIES PER GRAM ATOM OF OXYGEN AND DRYING THE PRECIPITATE-COATED PARTICLES SO PRODUCED (B) THEREAFTER REDUCING THE DEPOSITED COATING TO THE CORRESPONDING METAL BY BRINGING IT INTO CONTACT WITH A REDUCING GAS WHILE MAINTAINING A TEMPERATURE THROUGHOUT THE MASS BELOW THE SINTERING TEMPERATURE OF THE METAL, AND (C) SINTERING THE REDUCED PRODUCT TO A DENSE MASS AT A TEMPERATURE BELOW THE MELTING POINT OF THE METAL