ElectraWatch, together with the University of Virginia, proposes to develop a hand-held probe to measure the Degree of Sensitization (DoS) of 5XXX aluminum alloys on board Navy ships. Sensitization is caused by precipitation of Mg2Al3 at the grain boundaries. Because sensitized material can experience intergranular corrosion, exfoliation, and stress corrosion cracking (SCC) in marine atmospheric conditions, detection of sensitized material is essential for any structural integrity monitoring program. ElectraWatch will use differences in the electrochemical behavior (such as open circuit potential, linear polarization resistance, or electrochemical impedance) of the Al-Mg matrix and the Mg2Al3 precipitates to discriminate between the non-sensitized and sensitized material. Once the optimium electrochemical procedure is identified and developed, ElectraWatch will modify the electronics and software of its Embedded Corrosion Instrument (ECI) or Coating Health Monitor (CHM) to allow an inspector to measure and map the DoS of an aluminum structure and monitor its change over time.
Benefit: The results of a preliminary market study have identified U.S. Navy ships as the primary target customer for the DoS probe, with military and commercial shipyards as a large secondary market. Commerical ferries are a civilian market of interest. The study shows an intial market between one thousand and two thousand probes. By detecting sensitized material before significant corrosion occurs, the DoS probe can be used to reduce maintenance costs over the service lifetime of ships, minimize repair times, and increase fleet readiness.
Keywords: sensitized aluminum, Corrosion probe, Degree of Sensitization, aluminum-magnesium alloys
