Richard C. Alkire

Early Stages of Pitting Corrosion, or The Beginning of The End

Corrosion resistant alloys can fall unexpectedly because of events that can be traced to the formation of harmless small pits that grow into dangerous large pits, cracks, and crevices. We report observations on the onset of pitting corrosion, which often begins near surface inclusions, made with use of micro electro-chemical cells. Examples will be given for aluminum, stainless steel and nickel alloys. These experimental studies have led to various hypotheses of mechanism for how inclusions trigger early stages of pitting corrosion. These hypotheses draw upon reaction and transport processes involving several dozen chemical species that participate in a dozen or more homogeneous and heterogeneous reactions. An integrated experimental/computational approach will be described that utilizes tools including object oriented programming, robust parallel computing architectures, and sparse matrix storage techniques. We discuss the use of these methods for testing multiple reasonable hypotheses of mechanism.

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