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Item Combined effect of marine environment and pH on the impedance of reinforced concrete studied by electrochemical impedance spectroscopy(Springer, 2019) Goudar, S.K.; Das, B.B.; Arya, S.In the present investigation, behavior of OPC and fly ash based concretes were assessed by electrochemical impedance spectroscopy (EIS) technique after exposing the samples to the marine environment in combination with five pH levels (1, 4, 7, 10, and 13). Three different dosages of fly ash (15, 25, and 35%) were used to produce fly ash based concretes. After 90 days of exposure to the aggressive environment, the OPC and fly ash based concretes were tested for impedance analysis and corrosion resistance by electrochemical studies. For the equivalent electrical circuit in EIS study, a total of four electrical circuits were tried for the possible best fit of obtained Nyquist plots. The equivalent electrical circuits proposed by previous researchers failed to provide the best fit for the obtained Nyquist plots. A new equivalent electrical circuit is being proposed in this study which will provide the possible best fit of Nyquist plots when the concrete is being exposed to acidic and alkaline marine environment. It is observed that the pH of the marine environment has a decisive influence on the impedance of reinforced concrete. As the acidity of marine environment reduces to pH 1, the impedance of OPC and fly ash based concrete reduced significantly due to the severe deterioration of concrete composites especially because of acid attack and Cl− ions migration. However, in the case of alkaline nature of the marine environment (pH 13), there was comparably less deterioration of concrete composites which reflected in higher impedance values. The higher dosage of fly ash addition has led to substantial improvement in concrete impedance and also lower corrosion rate. © Springer Nature Singapore Pte Ltd. 2019.Item Electrochemical methods in tribocorrosion(Elsevier, 2021) Arya, S.; Joseph, F.J.Corrosion and wear mechanisms play a significant role in the degradation of components in various domains such as the petroleum industries, the automobile sector, and manufacturing and biomedical applications. The complex mechanisms of both corrosion and wear, including synergism, need to be well understood in order to design any system with maximum efficiency possible. This chapter is a brief on the concepts of electrochemistry in relation to tribocorrosion concepts. A three-electrode potentiostat system has proved to be a powerful tool in analyzing the chemical interactions within a specimen. The current-voltage response of the system enables the study of behavior of the surface and subsurface mechanisms in the specimen under existing tribocorrosive conditions. The passivation behavior in materials can be revealed with a detailed examination of electrochemical techniques. It also enables the monitoring of the response of coatings in the components in order to provide resistance against tribocorrosive attack. Various electrochemical techniques, such as open circuit potential, electrochemical impedance spectroscopy, polarization analysis, and their application in tribological systems, are discussed. © 2021 Elsevier Inc. All rights reserved.