Electrochemical Impedance Spectroscopy EIS Research Articles

In vivo electrochemical corrosion study of a CoCrMo biomedical alloy in human synovial fluids

The present study was initiated with the aim to assess the in vivo electrochemical corrosion behaviour of CoCrMo biomedical alloys in human synovial fluids in an attempt to identify possible patient or pathology specific effects. For this, electrochemical measurements (open circuit potential OCP, polarization resistance Rp, potentiodynamic polarization curves, electrochemical impedance spectroscopy EIS) were carried out on fluids extracted from patients with different articular pathologies and prosthesis revisions. Those electrochemical measurements could be carried out with outstanding precision and signal stability. The results show that the corrosion behaviour of CoCrMo alloy in synovial fluids not only depends on material reactivity but also on the specific reactions of synovial fluid components, most likely involving reactive oxygen species. In some patients the latter were found to determine the whole cathodic and anodic electrochemical response. Depending on patients, corrosion rates varied significantly between 50 and 750mgdm−2year−1.

Application of Electrochemical Noise to Investigate Corrosion Inhibition Properties of Some Azole Compounds on Aluminum in 0.25 M HCl

The corrosion inhibition properties of the benzothiazole BTH and benzotriazole BT inhibitors on the aluminum in 0.25 M HCl solution were studied. Electrochemical impedance spectroscopy EIS, electrochemical noise EN and potentiodynamic polarization techniques were used to investigate the inhibition properties of the inhibitors. Scanning electron microscope SEM was also utilized in order to investigate the surface morphology of the samples. Results showed that benzotriazole BT and benzothiazole BTH reduced the corrosion rate of the aluminum significantly. A higher corrosion inhibition efficiency of the BT compared with BTH was obtained. It was shown that EN is an appropriate technique for studying the corrosion inhibition properties of the corrosion inhibitors.

Performance Assessment of Electrodeposited Thin Epoxy Films

AbstractThe paper presents the experimental results concerning the performance assessment of electrodeposited epoxy films using electrochemical techniques (electrochemical impedance spectroscopy–EIS and anodic polarization) assisted by microscopical studies. The films were formed during the cathodic and anodic electrodeposition of a modified epoxy resin on carbon steel substrate. The specimens were tested in a normal aerated 3% NaCl solution at room temperature for a total period up to 1500 hours. Analysis of the impedance spectra has established an equivalent electric circuit with two time constants fitted to describe the electrodeposited epoxy film/carbon steel/electrolyte system. The time monitoring of the principal elements from the equivalent electric circuit were used to determine protective properties of the electrodeposited epoxy films. Results show a high performance of electrodeposited epoxy films, characterized by uniformity, insignificant porosity, very low water and ions permeability.

Impedance Analysis of DNA and DNA-Drug Interactions on Thin Mercury Film Electrodes

In this review we briefly summarize the results of impedance measurements (dependence of the differential capacitance C and/or impedance Z of the electrode double layer on potential E, C-E curves) or on frequency (Electrochemical Impedance Spectroscopy-EIS) of nucleic acids at mercury film electrode (MFE). Mercury film was plated either on a glassy carbon electrode (GCE) or pyrolytic graphite electrode (PGE). The dependence of the pseudocapacitance redox peak of echinomycin on concentration and on the ac voltage frequency was measured in bulk solution. Interaction of single- and double-stranded DNA with bis-intercalator echinomycin at nucleic acid-modified surface was studied using EIS with adsorptive transfer method.

Breakdown of passivity of aluminium alloys by intermetallic phases in neutral chloride solution

Aluminium alloys are successfully used in several technological applications. Aluminium itself has weak mechanical properties, hence it is alloyed with other elements and thermally treated to improve and tailor its characteristics. These processes remarkably change the original structure of Al from a homogeneous solid solution to a complex polyphase structure. The growth of intermetallics in the Al matrix allows the hardening process to take place but a modification of the chemical resistance of the alloy can occur. In this paper the influence of intermetallics, formed in some binary and ternary alloys (Al–Cu, Al–Cu–Be, Al–Mg–Zn), on the passivity breakdown and corrosion properties of aluminium is investigated and discussed with the aid of electrochemical measurements (anodic polarisation, electrochemical impedance spectroscopy EIS) and surface analysis (SEM, TEM, AES).