HIGH TEMPERATURE GASEOUS OXIDATION FOR PASSIVATION OF AUSTENITIC ALLOYS

摘要

PURPOSE: Provided is the corrosion resistance of austenitic alloys such as nickel-based alloy materials, and more particularly the formation of a chromium-rich, protective oxide layer on the surface of nickel-based alloy tubing. CONSTITUTION: A method of forming a chromium-rich layer on a surface of a nickel-based alloy workpiece containing chromium, comprises: (a) heating the workpiece to a temperature sufficient to oxidize the chromium; and (b) exposing at least one portion of the surface of the workpiece to a gaseous mixture of water vapor and at least one non-oxidizing gas to oxidize the chromium contained within the workpiece to form a chromium-rich layer on the at least one portion of the surface of the workpiece, wherein the surface of the workpiece comprises an inside surface of a tube used in a primary circuit of a water-cooled nuclear reactor.