Anti-corrosion and microstructural properties of Ni-W alloy coatings: effect of 3,4-Dihydroxybenzaldehyde.

In the present work impact of 3,4-Dihydroxybenzaldehyde on the microstructural and corrosion behavior of nanocrystalline Ni-W alloy coatings has been elucidated. A systematic investigation on the protection ability of Ni-W alloy coatings in 0.2 M H2SO4 solution was done with the aid of tafel polarization curves and electrochemical impedance spectroscopy (EIS) studies. Corrosion performance of the alloy films obtained in the absence and in the presence of different concentrations of 3,4-Dihydroxybenzaldehyde (0-500 ppm) in the bath was explained in the light of additive concentration. Compared to the blank and other concentrations of additive, 250 ppm of additive containing bath was predicted as the most promising one for the introduced citrate based Ni-W alloy electrodeposition. Low corrosion rate (0.06 mm/year) and high charge transfer resistance (2505.3 Ω cm2), for the electrodeposits, obtained from the bath containing 250 ppm of 3,4-Dihydroxybenzaldehyde supports for its high anticorrosion performance. The marked difference in the corrosion resistance property is ascribed to the formation of fine-grained deposits, smooth surface, and inclusion or adsorption of additive within the deposits in the presence of the additive (250 ppm) in the bath. Further, the adsorption of additive molecules on the metal surface was explored with the help of quantum chemical calculations based on DFT.

Anticorrosive properties of Hexa (3-methoxy propan-1,2-diol) cyclotri-phosphazene compound for carbon steel in 3% NaCl medium: gravimetric, electrochemical, DFT and Monte Carlo simulation studies.

The corrosion inhibition performance of Hexa (3-methoxy propan-1,2 diol) cyclotriphosphazene (HMC) on carbon steel in 3% NaCl solution was investigated by weight loss (WL), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) measurements, Density functional theory (DFT) and Monte Carlo (MC) simulation. The corrosion inhibition efficiency at optimum concentration (10-3M) is 99% of HMC at 298 K. The corrosion inhibition efficiency at 10-3 M decreases with increase in temperature. The adsorption of HMC on the surface of carbon steel obeyed Langmuir isotherm. Potentiodynamic polarization study confirmed that inhibitor anodic-type. DFT and Monte Carlo (MC) simulations based computational approaches were under taken to support the experimental findings. DFT studies revealed that HMC interact with metallic surface through donor-acceptor interactions in which the anionic parts act as electron donor (HOMO) and cationic parts behaved as electron acceptor (LUMO). The MC simulations study showed that studied HMC adsorb spontaneously on Fe (110) surface.