Investigations of pitting corrosion of magnesium by means of DEIS and acoustic emission

• Published in: Electrochimica acta Vol. 56; no. 23; pp. 7880 - 7884
• Main Authors: Orlikowski, Juliusz, Darowicki, Kazimierz
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 30-09-2011; Elsevier
• Subjects: Acoustic emission; Alkalinity; Applied sciences; Corrosion; Corrosion mechanisms; DEIS; Electric potential; Equivalent circuits; Exact sciences and technology; Magnesium; Metals. Metallurgy; Pitting corrosion; DEIS; Pitting corrosion; Magnesium; Basic solution; Medium effect; Acoustic emission; pH; Alkaline earth metal; Sodium Chlorides; Electrochemical impedance spectroscopy
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2010.12.021

The paper presents methodology and results of electrochemical examination of magnesium in 0.1
M NaCl solution with different pH. The measurements were conducted under potentiodynamic conditions using Dynamic Electrochemical Impedance Spectroscopy (DEIS). Analysis of DEIS results was performed based on electrical equivalent circuit. As the result of analysis changes of separate parameters of the equivalent circuit vs. potential for different pH values of the environment were obtained. Simultaneously with DEIS measurements an investigation using acoustic emission was conducted. The results showed that for pH higher than 12.50 the properties of layers on the surface of magnesium change significantly. One can observe a stable passive state that has properties considerably different from those of the layers that form in solutions with lower alkalinity. In such conditions the beginning of pitting corrosion process can be unequivocally determined by the level of acoustic emission and the values of electrochemical parameters.