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Corrosion behavior of CuAlNiMn in 0.9% NaCl solution

The corrosion behavior of the CuAlNiMn alloy in 0.9% NaCl solution at pH 7.4, and temperatures of 25, 37 and 50 oC, was investigated by electrochemical methods such as monitoring the open circuit potential, linear and potentiodynamic polarization methods. Investigations were also performed in 0.9% NaCl solution at 37 oC and different pH of solution (pH = 3.4, 5.4 and 7.4). Results of the investigations have shown that increasing the temperature leads to the shift of the open circuit potential values in the negative direction and also leads to increase of the corrosion current density and decrease of the polarization resistance values. Decreasing the pH of solution leads to the increase of the corrosion current density and decrease the values of polarization resistance. After the polarization measurements, corroded electrode surfaces was examined using an optical microscope and SEM. Microscopic images have shown the significant corrosion damages on the CuAlNiMn alloy surface, which manifests itself in the form of a thin leaf, with a larger part of the surface being covered with sheets of corrosion products loosely bonded to the surface which were elevated from the surface of the electrode. SEM surface analysis revealed the existence of two layers on the surface of the alloy: the exterior is extremely damaged, which represent sheets of loosely bonded surface, and an inner layer that also shows significant corrosion damage. The elemental composition of corrosion products on the surface of the samples was determined by EDS analysis.

CuAlNiMn alloy ; corrosion ; polarization ; electrochemical methods

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