Patent ID: 7794551

Claim:
A process for carburizing a metal article comprising: (1) heating the metal article to an elevated temperature, wherein the metal article is a green powder metal article, (2) coating the heated metal article with a graphite suspension to produce a graphite coated metal article, wherein the graphite suspension is comprised of graphite and an organic or inorganic liquid having a boiling point of at least 50° F. less than the elevated temperature to which the metal article is heated, (3) heat treating the graphite coated metal article under a non-oxidizing environment at a temperature which is sufficient to promote the diffusion of carbon into the metal structure of the article to produce a carburized metal article, and wherein the temperature is sufficient to sinter the powder metal article, and (4) cooling the carburized metal article to ambient temperature; wherein the metal article is heated in step (1) to a temperature which is 50° F. to 200° F. higher than the boiling point of the organic or inorganic liquid.