UNS A95052 (AA 5052) results very attractive for desalination applications due to its good corrosion resistance in seawater at temperatures up to 125°C, low cost, good thermal conductivity, and non-toxic corrosion products. The pitting potential, Epit, and the pit repassivation potential, Er, pit, of AA 5052 were measured in deaerated 65,000 ppm sodium chloride solutions at 30, 60 and 85°C. Pitting potential decreased with temperature, in accord with literature results. Er, pit was a function of anodic charge passed during pit growth stage. A complete evaluation of suitability of this alloy from a corrosion perspective requires also studies of crevice corrosion at different temperatures, considering that the metal plates for desalinators are usually in contact with rubber gaskets and seals. Different techniques were used to estimate crevice repassivation potential at 30, 60 and 85°C, in samples with an attached rubber O-ring as a crevice former. Some samples were exposed at the corrosion potential in deaerated 65,000 ppm sodium chloride (normal operation) and in aerated 65,000 ppm sodium chloride solution with 5 ppm Cu++ ions (possible contaminants in feed water), in order to predict corrosion performance of the alloy.

Subject
Pits, Circuit potentials, Aluminum, Repassivation potentials, Seawater, Open circuits, Crevices, Sodium chloride solution, Crevice corrosion, Pitting, Desalination, Aluminum alloys, Corrosion potential
Keywords:
aluminium alloys, crevice corrosion, pitting corrosion, repassivation potential
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2017
Association for Materials Protection and Performance (AMPP)
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