Niclosamide and dichlorphenamide: new and effective corrosion inhibitors for carbon steel in 1M HCl solution

This research demonstrates the effect of some amide compounds (1 and 2) as corrosion inhibitors on C-steel in 1.0 M of hydrochloric solutions utilizing mass reduction studies, electrochemical [potentiodynamic (PP), AC impedance measurements (EIS), electrochemical frequency modulation] techniques, and surface checks were used to illustrate the importance of amide compounds to the corrosion protection process of C-steel. The tests displayed that the inhibition efficiency (IE%) augmented with increase in amide dose but reduced with growth of temperature. The highest inhibition efficiency is 99% for compound (1) and 98.8% for compound (2) at maximum dose tested (50 µM) by polarization method. PP data show that these compounds affect both cathodic and anodic processes (i.e. mixed type) and were adsorption on the carbon steel obeying Langmuir adsorption isotherm. The EIS results indicate that the changes in impedance parameters are related to the adsorption of amides on the alloy surface. Scanning of electron microscopy, energy transmitted X-ray—Atomic force microscopy studied the morphology of inhibited C-steel. Graphic abstract

Atomic layer deposited V2O5 coatings: a promising cathode for Li-ion batteries

A modified, thermal atomic layer deposition process was employed for the pulsed chemical vapor deposition growth of vanadium pentoxide films using tetrakis (dimethylamino) vanadium and water as a co-reagent.Depositions were carried out at 350oC for 400 pulsed CVD cycles, and samples were subsequently annealed for 1hour at 400°C in air to form materials with enhanced cycling stability during the continuous lithium-ion intercala­tion/deintercalation processes. The diffusion coefficient was estimated to be 2.04x10-10 and 4.10x10-10 cm2 s-1 for the cathodic and anodic processes, respectively. These values are comparable or lower than those reported in the literature, indicating the capability of Li+ of getting access into the vanadium pentoxide framework at a fast rate. Overall, it presents a specific discharge capacity of 280 mAh g-1, capacity retention of 75 % after 10000 scans, a coulombic efficiency of 100 % for the first scan, dropping to 85 % for the 10000th scan, and specific energy of 523 Wh g-1.

CATHODIC AND ANODIC PROCESSES IN SOLUTIONS OF ZINC SULFATE IN PRESENCE OF SURFACTANTS

We investigated the cathodic and anodic processes in solutions of zinc sulfate in the presence of a surfactant and the background solution of sodium sulfate over a wide potential range. It was shown that anionic surfactants increase the anode current and the cation ones decrease. An explanation for the increase in the magnitude of the anode current in presence of anionic surfactants and reduction in the presence of cation-active surfactant was done. Experimental data and thermodynamic calculations has shown that the reason for the lack of influence of surfactants on the magnitude of the cathode current for the background electrolyte solution of sodium sulfate is probably associated with the processes of sulfate reduction.

Modeling of the Formation Processes of Nanocomposite Coatings by the Electrocodeposition

The coupled mathematical model of electrocodeposition process on the rotating cylinder electrode is presented. Low Reynolds k-e model with Abe-Kondoh-Nagano damping functions is used to describe mass transport of electrolyte. The cathodic and anodic processes are described by the tertiary current distribution theory. Mass transfer of electrolyte ions is described by diffusion-convection equation and is studied throughout the volume of the electrolyte cell. The simulation of electrocodeposition of Cu-Al2O3 nanoparticles on rotating cylinder electrode of are presented. It is found that the unsteady diffusion layer is formed close to the rotating electrode surface. Also it was found that the sign of the zeta potential of nanoparticles has a decisive influence on the possibility of forming the composite coatings. The results of mathematical modelling are in good agreement with the experimental data.

Electrolysis of metal oxides in MgCl2based molten salts with an inert graphite anode

Electrolysis of solid metal oxides has been demonstrated in MgCl2–NaCl–KCl melt at 700 °C taking the electrolysis of Ta2O5as an example. Both the cathodic and anodic processes have been investigated using cyclic voltammetry, and potentiostatic and constant voltage electrolysis, with the cathodic products analysed by XRD and SEM and the anodic products by GC. Fast electrolysis of Ta2O5against a graphite anode has been realized at a cell voltage of 2 V, or a total overpotential of about 400 mV. The energy consumption was about 1 kW h kgTa−1with a nearly 100% Ta recovery. The cathodic product was nanometer Ta powder with sizes of about 50 nm. The main anodic product was Cl2gas, together with about 1 mol% O2gas and trace amounts of CO. The graphite anode was found to be an excellent inert anode. These results promise an environmentally-friendly and energy efficient method for metal extraction by electrolysis of metal oxides in MgCl2based molten salts.

Electrochemical Investigation of Triadimenol as Corrosion Inhibitor for Copper in 0.5mol/L H2SO4 Solution

This paper chose triadimenol as a corrosion inhibitor of copper in 0.5mol/L sulfuric acid. The properties of corrosion inhibition were investigated by the polarization measurement and electrochemical impedance spectroscopy (EIS). Polarization curves showed that both cathodic and anodic processes of copper corrosion were suppressed. The inhibiting efficiency increased as the increment of the inhibitor concentration and reached 86.7% at 50 mg/L. The results obtained from EIS measurements are in line with that obtained from potentiodynamic polarization. Finally, a mechanism of inhibition is proposed and discussed.

Electrochemical Investigation of the Adsorption Behaviour of Guanine on Copper in Acid Medium

The guanine as a corrosion inhibitor for copper in 0.5 mol/L sulfuric acid solution was investigated using weight loss experiment, polarization curves, AC impedance. The results showed that the inhibition performance of the guanine depended on the concentration of the inhibitor and the highest inhibition efficiency of the guanine reached 92.2% at 1×10-3mol/L in 0.5 mol/L sulfuric acid solution. The potentiodynamic polarization measurements showed that both cathodic and anodic processes of copper corrosion were suppressed and the guanine acts essentially as a mixed-type inhibitor. The results obtained from EIS measurements are in good agreement with that obtained from potentiodynamic polarization. The adsorption of the guanine is found to obey Langmuir adsorption isotherm and belong to physisorption.

Cavitation Corrosion Behavior of Anodized Aluminum Alloy

The cavitation corrosion behavior and surface morphology of anodized aluminum alloy in 3.5% sodium chloride (NaCl) solution were investigated using weight loss and scanning electron microscopy. The electrochemical corrosion mechanism during cavitation corrosion was studied using electrochemical polarization and electrochemical impedance spectroscopy (EIS). The cavitation corrosion process could be divided into three stages: quick removal of the porous outer layer, slowly fragmenting and removing of the dense inner layer, and fast erosion of the aluminum alloy. Increasing the thickness of the anodized layer improved the cavitation corrosion resistance of the anodized aluminum alloy. Electrochemical corrosion processes under cavitation conditions were controlled by mixed cathodic and anodic processes. EIS spectra of anodized aluminum alloy under cavitation conditions resembled those from porous electrodes. Cavitation accelerated the electrochemical corrosion. Cavitation corrosion of anodized aluminum alloy showed strong synergism between mechanical and electrochemical corrosion factors.

Adsorption Behavior and Corrosion Inhibition of EPP for Q235 Steel in H2SO4 Solution

The inhibition effect of N,N-diethylammonium O,O'-di(2-phenylethyl)dithiophosphate (EPP, [NH2(Et)2][S2P(OCH2CH2Ph)2]2) against the corrosion of Q235 steel in H2SO4solution was studied by weight loss measurement, potentiodynamic polarization and SEM(scanning electron microscope) techniques. The results show that EPP acts as an excellent corrosion inhibitor in 5% H2SO4by suppressing simultaneously the cathodic and anodic processes via chemical adsorption on Q235 steel surface, which complies with the Langmuir adsorption isotherm. Polarization curves indicate EPP is a mixed-type inhibitor. The effects of temperature, acid concentration and immersion time were also studied.