The structure and properties of the passive film formed on the surface of AISI 316 stainless steel in aqueous ethanoic acid have been investigated using EIS. Experiments were carried out at 30 °C in different concentrations of ethanoic acid. Effects on the film properties due to the change of electrode potential, exposure durations and addition of chloride ions to the electrolyte were also studied. Impedance parameters were determined using simple model and equivalent electrical circuit. Results suggest the formation of multilayered passive film on the steel surface. The film possessed dual structure. Inner layers were thin and compact, whereas the outer layer was porous and defective. The measured capacitive behavior was of non ideal nature and hence replaced by constant phase element or CPE. Formation of the passive film and the change in its structure has been explained using impedance parameters.

The corrosion behavior of mild steel in dimethyl sulfoxide containing various concentrations, i.e., 0.001, 0.005, 0.010, 0.015 and 0.020 M of hydrochloric acid has been studied in presence of 0.1 M tetra ethyl ammonium chloride as supporting electrolyte by applying electrochemical techniques. The results of these experiments have been supplemented by surface analysis of the samples exposed to corrosive solution under different experimental conditions. The electrochemical investigation was done potentiostatically by varying the concentration of HCl in DMSO and the experimental temperature as well.

A few 1-aryl-2,5-dithiohydrazodicarbonamides and their triphenyltin and dibutyltin complexes have been studied as corrosion inhibitors for mild steel in dimethyl sulphoxide containing HCl at 25 ºC using electrochemical polarisation technique. Among dithiohydrazodicarbonamides, ethoxyphenyl derivative exhibited maximum inhibition efficiency (IE) followed by benzyl and phenyl analogues. The same order of IE was observed in their corresponding organotin complexes; however, IE of a complex was found to be significantly higher than that of the constituents ligand. All organotin complexes behaved predominantly as cathodic inhibitors. Triphenyltin complexes proved to be better corrosion inhibitors than their dibutyltin analogues.

The inhibition of mild steel corrosion in 1N sulphuric acid was studied in the presence of various concentrations (10-150 ppm) of substituted dithiobiurets and their molybdenum and tungsten complexes at 25 °C. All the compounds behaved as ambiodic corrosion inhibitors for mild steel and were considered to inhibit the corrosion by getting adsorbed on the surface. The inhibition efficiencies (IEs) of the complexes, in general, were found to be appreciably higher than those of corresponding ligands. However, the IE values of the complexes of molybdenum and tungsten of the same ligand did not differ much in their magnitude indicating thereby that the nature of central metal ions hardly influenced the inhibition efficiency. The slight difference in the IEs of the complexes at a given concentration seems to be caused by the slight difference in their size. The variation in IEs of different derivatives of ligands has been attributed to change in their size, number of active sites for adsorption and the electron density on these active sites. Scanning Electron Microscopy was used to study the surface of corroded and inhibited specimens.