Surface Treatment of High Performance Marine Alloys to Enhance Crevice CorrosionResistance in Critical Seawater Applications

摘要

Electropolishing and applied cerium surface treatments to enhance the crevicecorrosion resistance of high performance marine alloys used for critical seawater applications have been investigated. Because of its known susceptibility to crevice corrosion under certain adverse geometrical conditions, Ni-base alloy UNS N06625 was selected as the test material. Crevice corrosion tests were performed in natural and chlorinated seawater over a wide range of ambient temperatures for up to 180 days. Testing comprised the use of two different crevice conditions which previously contributed to crevice corrosion of the test alloys in the as-produced condition. Flowing seawater tests results were complemented by the results of electrochemical tests and SEM/EDS analysis. While both surface treatments markedly improved crevice corrosion resistance, electropolishing provided the greatest improvement in the seawater tests and enhanced performance during anodic potentiodynamic polarization testing in a low pH simulated crevice solution. The role of surface chromium depletion in the as-produced material is discussed.