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Study about the corrosion behavior of 5052-H34 aluminum alloy anodized by electrolytic plasma


Aluminum alloys have good corrosion resistance, but need surface treatment for use in aggressive environments. Generally, such alloys are anodized in chromate solutions that result in oxide films with excellent corrosion resistance. However, there is a search for eco-friendly technologies that replace the chromo-based processes, due to the dangers it offers to humans and the environment. Among some technologies, the plasma electrolytic treatment presents several advantages, such as one step process, shorter deposition, innocuous chemical solutions, and oxide coatings with better mechanical and anti-corrosive properties than those obtained in conventional anodizing. In this work 5051-H34 aluminum alloy will be anodized by electrolytic plasma fed by direct current (DC) source. The corrosion resistance of the alloys will be evaluated as a function of electrolyte and treatment time. Electrolytic solutions will be prepared from a silicate (Na2SiO3), a sulfate [Al2(SO4)3], a phosphate (Na3PO4), and a borate (Na2B4O7.10H2O), with electrical conductivity adjusted by the addition of a fluoride (KF). Electrochemical tests of the treated substrates will be performed at open circuit potential in 3.5% sodium chloride (NaCl) solution. Chemical structure, morphology and hardness of the oxide films obtained by electrolytic plasma will be analyzed for obtaining the understanding about the anti-corrosive behavior of coated alloys. (AU)

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