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Cyclic voltametry and potentiodynamic single sweep techniques are used to study the electrochemical behaviour of lead in Na₂CO₃ solutions containing various concentrations of ClO₄^‐ as aggressive anion. The effects of different concentrations, in terms of destruction of passivity and initiation of pitting corrosion, were monitored with reference to the change in integrated anodic charge. It was found that Δq_a (taken as a measure of the extent of pitting) varies linearly with log C_ClO4‐. The pitting corrosion potential, E_pitting, varies with log C_ClO4‐ according to sigmoidal curves. These curves are explained on the basis of formation of passive, active and continuously propagating pits. Additions of aliphatic amines shift the pitting corrosion potential, E_pitting, into the noble (positive) direction, indicating the inhibition action of the added amines on the pitting attack. E_pitting varies with the logarithm of the inhibitor concentration according to: E_pitting = a + b log C_inh. The inhibition of pitting corrosion by the aliphatic amines is assumed to be due to either competitive adsorption between the CO₃^2– with ClO₄^‐ anions, and/or the chemisorption of the amine on the metal with the formation of a metal‐nitrogen coordination bond. The efficiency of these compounds as pitting corrosion inhibitors increases with the increase in the chain length of the alkyl group.

The effect of the addition of aggressive salts such as LiCl, NaCl, KCl, RbCl and MgCl2 on the steady‐state potential of a Zn electrode previously equilibrated in a passivating chromate solution is established. S‐shaped curves are obtained for the variation of the steady‐state potential with the quantity of aggressive salt added. For each inhibitor concentration, Cinh, the addition of aggressive ions up to a certain concentration has no effect on the passivity of Zn. However, higher Cl ion concentration causes destruction of the passive film and initiation of pitting corrosion. Destruction of passivity occurs after an induction period which decreases with the increase in the concentration of the attacking ion and/or the decrease in that of the inhibiting ions. The concentration of aggressive ion, Cagg, that can be tolerated by a certain concentration of the inhibiting ions, Cinh, is given by the relation : log Cinh =K + n log CCl−, where K and n are constants. The efficiency of these salts in initiating pitting corrosion increases in the order RbCl ≤ MgCl2, ≤ KCl < NaCl < LiCl. The change in the degree of aggressivity of these salts could be attributed either to the incorporation of the cations in the passive film or to their effect on pH.

The electrochemical behaviour of zinc in different concentrations of Na₂SO₄ (pH = 6.0) was investigated using the potentiodynamic anodic polarization single sweep and cyclic voltammogram techniques. The anodic portion is characterized by one distinct peak corresponding to Zn(OH)₂ or ZnO. This is followed by a passive region up to a certain potential; the passive current suddenly rises steeply without any sign of oxygen evolution. This denotes the breakdown of the passive film and initiation of pitting corrosion. It was found that the breakdown potential depends on the sulphate concentration, type of aeration, scan rate, solution temperature and pH. The pitting initiation may be explained through the adsorption of SO₄^2– anion on the oxide film formed. This decreases the repair efficiency and causes further metal dissolution. From the cyclic voltammogram of zinc in different concentrations of Na₂SO₄, it was found that the change in the integrated anodic charge, Δq_a, which is taken as a measure of the extent of pitting, varies linearly with concentration of SO₄^2– anion.

The potentiodynamic anodic polarization curves for the lead electrode were obtained in 0.1 mol L‐1 KOH solution in the absence and presence of C103‐ or C104‐ as aggressive ions at different concentrations. Lower concentrations of these ions have no significant influence on the passive film, while higher concentrations raise the active dissolution current density, and cause destruction of passivity and initiation of pitting corrosion. The critical pitting corrosion potential varies with the concentration of the aggressive ions according to sigmoidal curves. These curves were explained on the basis of the formation of passivitable, active and continuously propagagting pits depending on the range of the aggressive ion concentration. Additions of increasing concentrations of chromate, phosphate, sulphate and carbonate ions cause a shift of the critical pitting potential in the noble direction accounting for increase resistance to pitting attack (inhibition). The pitting corrosion potential varies with the concentration of the inhibitive ions, in the presence of a constant concentration of the aggressive ions, according to curves of sigmoidal shape. From these curves one can determine the minimum concentration of the inhibitive ions necessary for inhibition of pitting corrosion to occur.

Corrosion inhibitors are widely used in industry, although in many cases their surface chemistry is not well understood. Several nitrogen‐containing organic compounds have been used as corrosion inhibitors. Corrosion inhibition is a surface process which involves the specific adsorption of inhibitors on the metal surface. The extent of inhibition of metallic corrosion may depend on the nature of the metal surface and extent of adsorption of the inhibitor. The type of interaction of the inhibitor on the metal surface during corrosion has been deduced from its adsorption characteristics.

To show the effect of organic compounds containing O and N atoms on the corrosion inhibition of Cu in HNO₃ and; the effect of some donating substituent groups on the corrosion inhibition.

A range of published papers (1956‐1995), which aim to discuss the effect of organic compounds on the corrosion inhibition process. Two methods were used to determine the rate of corrosion, these methods were weight loss and polarisation. The effect of temperature and concentration were studied. The thermodynamic parameters for the process were computed and discussed.

Provides information about weight loss and polarisation methods and how to prepare the Cu samples before and after tests. This will provide many academics relevant information before teaching or researching duties.

The paper may be using withdrawing substituting groups in addition to donating groups, this will improve the discussion, also the paper does not use the technique of impedance spectroscopy for comparison.

To use Cu alloy for comparison and to use other compounds with larger molecular weights.

The use of some phthalimide derivatives as corrosion inhibitors for Cu in HNO₃, provide more information on Cu corrosion for academic researchers and provide practical help for starting researchers.

The cathodic polarization of Ni in hydrochloric acid solutions has been investigated using the galvanostatic technique. The rate of hydrogen evolution reaction was found to depend on the concentration and pH of the solution. The reaction order with respect to hydrogen ion was found to be one. The rise of temperature enhances the rate of hydrogen evolution reaction. The activation energy, \triangleH*, for such process was found to be 10kcal. mol^‐1. The effect of aniline and some of its derivatives (o‐, m‐ and p‐anisidine) on the cathodic polarization of nickel in 1M HCl solution was also studied. These compounds were found to inhibit the rate of hydrogen evolution reaction without affect on its mechanism. The inhibition efficiency depended on the concentration and type of the inhibitor. The inhibition efficiency ranged between 73 and 92 per cent at the highest concentration (10^‐2M), and ranged between 24 and 60 per cent at the lowest concentration (10^‐4M). This corresponded to surface coverage of the metal by the inhibitor. The degrees of surface coverage, θ, were calculated and found to increase with the inhibitor concentration. The results show also that, the inhibitors were adsorbed on the nickel surface according to Langmuir adsorption isotherm.

The purpose of this paper is to study the electrochemical behavior of Sn electrode in Na₂B₂O₇ solutions in the absence and presence of NaNO₃ as a pitting corrosion agent.

The electrochemical behavior of Sn electrode was studied by using cyclic voltammetry and potentiodynamic polarization measurements and complemented with scanning electron microscopy examinations.

This paper shows that in the absence of NO₃ − ions, the anodic polarization of Sn electrode exhibits active/passive transition. Addition of various concentrations of NO₃ − anions to the borate solution enhances active anodic dissolution and tends to break down the passive oxide film at a certain pitting potential. The pitting potential, and hence the pitting corrosion resistance, decreases with increasing NO₃-ion concentration and temperature but increases with scan rate and repetitive cycling. Addition of CrO₄²⁻, WO₄²⁻ or MoO₄²⁻ oxyanions to the borate nitrate solution inhibits the pitting corrosion of Sn.

This is the first study that shows the effect of NO₃ − ion as a pitting corrosion agent.

This study aims to study electrochemically and by weight-loss experiments the effect of UAE Rhazya Stricta Decne extract on the corrosion inhibition of mild steel in 1.0 M HCl solution, which will serve researchers in the field of corrosion.

Weight loss measurements were carried out on mild steel specimens in 1.0 M HCl and in 1.0 M HCl containing various concentrations (ranging from 2.0 to 0.002 g/L.) of the UAE Rhazya Stricta Decne extract at temperatures ranging from 303 to 343 K.

The aqueous Rhazya Stricta Decne leaves extract was found to be a highly efficient inhibitor for mild steel in 1.0 M HCl solution, reaching about 90 per cent at 2.0 g/L and 303 K, a concentration considered to be very moderate. Even with one-tenth of that concentration, 0.2 g/L, an inhibition of about 82 per cent was obtained at 303 K. The rate of corrosion of the mild steel in 1.0 M HCl is a function of the concentration of the Rhazya Stricta Decne extract. This rate increases as the concentration of the Rhazya Stricta Decne extract is increased. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature.

This inhibitor could have application in industries, where HCl solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary.

This paper is intended to be added to the family of green corrosion inhibitors which are highly efficient and can be used in the area of corrosion prevention and control.

The purpose of this paper is to study electrochemically and by weight loss experiments the effect of P,P′‐Bis (triphenylphosphonio) methyl benzophenone dibromide (TPPMB) on the corrosion inhibition of mild steel in 1.0M HCl solution, which will serve researchers in the field of corrosion.

Weight loss measurements were carried out on mild steel specimens in 1.0M HCl and in 1.0M HCl containing various concentrations (2×10⁻⁸M and 2×10⁻⁵M) of the laboratory synthesized TPPMB at temperatures ranging from 303 to 343 K.

TPPMB was found to be a highly efficient inhibitor for mild steel in 1.0M HCl solution, reaching about 98% at the concentration of 2×10⁻⁵M at 303 K, a concentration and temperature considered to be very moderate. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature.

This inhibitor could have application in industries, where hydrochloric acid solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary.

This paper is intended to be added to the family of phosphonium salt corrosion inhibitors which are highly efficient and can be employed in the area of corrosion prevention and control.