Porous iron electrodes containing metal additives have been used in nickel-iron cells. The impedances of these electrodes were measured over a wide range of frequency 10⁴ Hz to 10⁻² Hz in 6 M KOH + 0·63 M LiOH solutions. Using a cylindrical pore model, porosity and its related parameters were calculated. It is found that Hg and S provide favourable porosity and thus enhance the discharge capacity.

Cyclic voltammetric studies were carried in mixtures of SnSO₄ and ZnSO₄ containing sodium gluconate in thepH range 6 to 8 at 30° and 60°C. The stannous gluconate ions hinder the deposition of zinc while zinc gluconate ions favour the tin deposition in Sn-Zn alloy formation. This formation of Sn-Zn alloy film is a regular type of alloy deposition. Stripping voltammetric curves revealed the likely presence of zinc-rich tin intermediate phases in the Sn-Zn alloy films.

2-Carboxy ethyl phosphonic acid (2-CEPA) in the presence of Zn²⁺ ions synergistically inhibits mild steel corrosion in 60 ppm chloride solutions. Calcium gluconate (CG) enhances inhibition. Electrochemical and weight change methods are used to study synergistic inhibition, and the mechanism of inhibition is discussed.

2-Carboxy ethyl phosphonic acid (2-CEPA) in presence of zinc ions synergistically inhibits mild steel corrosion in 60 ppm chloride solutions. Addition of calcium gluconate provides enhanced inhibition. Spectrochemical analyses of the solution and the surface inhibitor film reveal the presence of Zn (OH)₂ and iron phosphono gluconate complex.

Cyclic voltammetric measurements were made on pure copper, nickel and 70/30 copper-nickel alloy in sodium sulphate and sodium chloride (0.5 M) solutions. In sodium sulphate solution the passivation of copper and nickel is through oxide formation. The passive film on copper nickel alloy is found to have nickel ions ingress along with copper oxide by volume diffusion. Nickel ions cause hindrance to the reduction of copper oxide to copper. The presence of chloride ions increases the dissolution of nickel while copper is passivated. The formation of CuCl₂ and its subsequent hydrolysis to hydroxide prevents the dissolution. Introduction of nickel in copper depassivates the copper and hydrolysis of monovalent copper complex is prevented by the ingress of nickel ions. The formation of NiCl₂ along with CuCl₂ is facilitated by chloride ions.

Cupronickels offer enhanced corrosion protection in marine environments by the formation of passive films on the surface. Cyclic voltammetric studies were carried on cupronickels in chloride solutions at pH 6.3 to understand the role of chloride ions in passive film formation. Increase in nickel content of the alloy and of chloride ions in solution decreases film resistance. Chloride ions take part in reduction of the passive film to copper. A solid-state model for passive film formation involving chloride ions has been attempted.