Patent ID: 7520940

Claim:
A method of forming an oxide layer on a powder metal part, comprising: placing the powder metal part in a furnace; raising a temperature of the furnace to a first temperature; maintaining the furnace at the first temperature for a first predetermined amount of time; maintaining the powder metal part in a steam environment for a period of time greater than or equal to about 15 minutes; maintaining the furnace at a second temperature between about 460° C. and about 500° C. for a period of time greater than or equal to about 10 minutes, the second temperature being higher than the first temperature; maintaining the furnace at a third temperature between about 570° C. and about 610° C. for a period of time greater than or equal to about 30 minutes; and forming an oxide layer on the powder metal part, wherein the oxide layer has a thickness greater than about 7 microns.