Sintered iron bodies and processes therefor

Claim 1

THE METHOD OF MAKING SINTERED IRON BODIES OF IMPROVED STRENGTH FROM THERMOCHEMICALLYCOATED IRON POWDERS, SAID METHOD COMPRISING THE STEPS OF: PROVIDING A SINTERABLE MASS CONSISTING ESSENTIALLY OF AN INTIMATE ADMIXTURTE OF (A) IRON POWDERS, AT LEAST A MAJOR PART OF WHICH POWDERS CARRIES A COPPER COATING AMOUNTING TO BETWEEN ABOUT 4% AND 30% OF THE TOTAL WEIGHT OF THE IRON POWDERS, SAID COATING HAVING BEEN APPLIED TO THE SAID MAJOR PART OF THE IRON POWDERS BY A THERMOCHEMICAL REACTION BETWEEN SAID IRON POWDER AND FINELY-DIVIDED COPPER OXIDE AT TEMPERATURES BETWEEN ABOUT 1000* F. AND 1500* F. IN A NON-OXIDIZING ATMOSPHERE, AND (B) BETWEEN ABOUT 1/4% AND 4% IN METALLIC TIN EQUIVALENT IN FINELY-DIVIDED FORM, BY WEIGHT OF THE COPPERCOATED IRON POWDER; SINTERING SAID SINTERABLE MASS IN A REDUCING ATMOSPHERE AT TEMPERATURES BETWEEN ABOUT 1800* F. AND 2200* F.; AND COOLING SAID SINTERED MASS IN A NON-OXIDIZING ATMOSPHERE.