فهرست مطالب t. shahrabi farahani

The increasing demand for energy resources and the environmental problems due to the consumption of fossil fuels has drawn attention to the creation of clean and renewable energy resources. Hydrogen is one of the promising energy resources for future fuels. Hydrogen can be produced with high purity and without emitting pollution via electrochemical water splitting. Notably, this method requires low-cost, active, and stable electrocatalysts with good corrosion resistance. Therefore, the selenide of transition metals, especially Nickel, was considered in research. Besides, one of the most important disadvantages of transition metals selenides is their low electrical conductivity. Therefore, this research used reduced graphene oxide to improve the electrical conductivity and increase the electrochemical active surface area. Therefore, reduced graphene oxide was electrodeposited on the surface of nickel foam.Furthermore, nickel selenide was coated on the rGO/NF surface via electrodeposition. As a result, the high electrical conductivity and high available surface area led to the achievement of low overpotential at the current density of 10 mA.cm-2 . These values for HER and OER were 68 mV at current density of 10 mA.cm-2 and 281 mV at current density of 200 mA.cm-2 , respectively. In addition, the results of the 24 hours chronopotentiometry test in both anodic and cathodic regions promise high stability and corrosion resistance of the synthesized electrode in the alkaline environment of 1 M KOH solution.

In this study, a synthesize hybrid nanocarrier by co-precipitation method consisting of double-layer hydroxide (LDH) and multi-walled carbon nanotubes (MWCNT) was used as a nanocarrier containing corrosion inhibitor in order to enhance the corrosion protection performance of applied epoxy coating on St12 substrate in 3.5 wt.% NaCl environment. Also, by adding sodium triphosphate (TSP) nanoparticles as a corrosion inhibitor to the synthesized hybrid nanoparticles, a smart anti-corrosion coating was made, which confirmed the correctness of the synthesis of MgAl-LDH/OMWCNT hybrid nanoparticles and the correction of loading of the TSP inhibitor molecule in the MgAL-LDH /OMWCNT structure by characterization tests such as XRD, Raman and FTIR and the corrosion inhibition mechanism was carried out using EIS, polarization and FE-SEM/EDS analyses. The polarization results showed the 20% reduction of corrosion current density. In the following, the anti-corrosion properties of the epoxy composite coating were investigated by EIS analysis. The results showed the active inhibition of the TSP-LDH/OMWCNT/EP coating in the scratch areas, in the other word an enhancement of Rct, from 65.97 k.cm2 for pure EP sample to 94.87 k.cm2 for TSP-LDH/OMWCNT/EP indicated the reflection of improvement self-healing behavior of the system. Moreover, the results of pull-off adhesion and cathodic delamination tests demonstrated the durability of the anti-corrosion properties of the coated samples with LDH/OMWCNT and TSP-LDH/OMWCNT nanoparticles due to better compatibility with the epoxy, which led to a decrease in adhesion loss and a 36% decline in the diameter of cathodic delamination to 36% and so it indicated the improvement in the corrosion resistance of epoxy coating.

In this paper, organic/inorganic hybrid pigment based on sodium lignosulfonate and zinc acetate was synthesized for reducing the corrosion rate of St12 steel immersed in 3.5 wt.% NaCl solution. To evaluate the anti-corrosion protection performance of steel substrate immersed in solution in the presence and absence of synthesized pigment, electrochemical impedance spectroscopy, potentiodynamic polarization and open circuit potential tests were performed. Scanning electron microscope equipped with energy dispersive spectroscopy and X-ray diffraction tests were also used to evaluate the inhibition mechanism of pigment. The results of the electrochemical impedance spectroscopy test showed that the charge transfer resistance of steel sample increased from 2958 Ω.cm2 to 7500 Ω.cm2 after 120 h of immersion in the saline solution with pigment. The formation of an inhibitive film consisting of zinc and lignosulfonate complexes on the surface of the steel substrate is the main reason for enhancing of the charge transfer resistance of the steel substrate in the presence of the synthesized pigment.

Artificial neural network model is a high precision predictive tool for unknown values without performing the related experiments. It can be developed and utilized for prediction of nonlinear corrosion processes. In this way, owning a numer of input values, the output can predicted, exactely. In present work, first, the effect of holding time, hydrodynamic conditions and temperature were investigated on the inhibiting efficiency of 7-Hydroxyphenoxazone on steel corrosion in 1.0M HCl solution by electrochemical impedance spectroscopy (EIS). Then, the experimental variables such as concentration, immersion time, and hydrodynamic condition were taken as the input values and the corrosion inhibiting efficiency as the output value of artificial neural network model. Results showed that by increasing immersion time up to 8 hours, with 100ppm of 7-Hydroxyphenoxazone, the polarization resitance increases from 1660 to 2260 Ωcm2 and inhibition efficiency reaches to 91%. Also, by increasing rotational speed up to 500 rpm and temperature up to 550C, the inhibition efficiency decreases from 86.6% to 24% and 60%, respectively. The prediction results of artificial neural network indicated the good agreement with experimental data and the trained values of artificial neural network predicted the inhibiting efficiency values with average error less than 1%.