Comparison of electrochemical current noise signals arising from symmetrical and asymmetrical electrodes made of Al alloys at different pH values using statistical and wavelet analysis. Part II: Alkaline solutions

Application of asymmetrical configuration in electrochemical noise to investigate corrosion inhibition of aluminum alloy by Ranunculus Arvensis/silver nanoparticles

Asymmetric Configuration (As-Co) in the electrochemical noise (EN) was used to evaluate Ranunculus Arvensis / silver nanoparticles (RA/Ag NPs) as corrosion inhibitor for aluminum alloy (AA 2030) when gets exposed to 3.5% NaCl media. The ECN results of Asymmetric Configuration (As-Co) and Symmetric Configuration (Sy-Co) were interpreted using wavelet and statistical methods. The standard deviation of partial signal (SDPS) plots derived using of wavelet. The SDPS plot of As-Co demonstrated that the quantity of electric charge (Q) decreased with the addition of the inhibitor up to the optimum amount (200 ppm) due to the decreased corrosion rate. Moreover, the use of As- Co leads to record signal of one electrode and prevent recording extra signals arising from two identical electrodes which confirmed by the statistical parameters. The As-Co made of Al alloys were more satisfactory for estimating inhibiting effect of RA/Ag NPs compared to Sy-Co. Besides, aqueous extract of Ranunculus Arvensis (RA) plant as reducing agent mediates the synthesis of silver nanoparticles (RA/Ag NPs). The prepared NPs have been elaborately characterized using Field-Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD) analysis, and Fourier-Transform Infrared Spectroscopy (FT-IR) that revealed suitable synthesize of the RA/Ag NPs.

A study on synergistic effect of chloride and sulfate ions on copper corrosion by using electrochemical noise in asymmetric cells

The current study includes a systematic examination of copper corrosion initially in each of NaCl and Na₂SO₄ solutions separately and then in the mixture solution of Cl⁻ and SO₄²⁻ ions as aggressive ions. Electrochemical current noise (ECN) signals resulting from asymmetric (Asy) as well as symmetric (Sym) cells have been interpreted using wavelet transform (WT) along with statistical procedures. The signals have been detrended and the decomposition of every signal has been carried out into 8 crystals. Then the standard deviation of every crystal has been illustrated with the standard deviation of partial signal (SDPS) plots. The Asy electrodes increased the pitting detection on copper compared with the Sym ones, indicating higher efficiency of the Asy electrodes. Asymmetric-copper electrodes have been studied using SDPS plots at different temperatures (40, 60, as well as 80 °C). Finally, in order to partly understand the effect of Cl⁻ and SO₄²⁻ ions on the corrosion of copper, the stabilization of Cu²⁺ cations by Cl⁻ and SO₄²⁻ ions in aqueous solutions have been modeled by DFT calculations. The derived results are in accordance with the experimental data.

Blocking Hydrogen Diffusion in Palladium Cathode i—Analyzed by Electrochemistry; ii—Analyzed by Chaos

Electrochemical chaos is caused when, during diffusion, hydrogen and, at worst, tritium is trapped in palladium after the formation of adsorbates. The mechanism leads to cracking corrosion, as seen by scanning electron microscopy. The instabilities were apprehended from voltammetry and electrochemical impedance spectroscopy in the active potential where the cathodic hydrogen is charged from two models of transients. Tests performed using an electrochemical chaos analyzer simplify the expertise of the palladium cathode in focusing on the blocking diffusion of hydrogen. A complex electrical circuit of chaos is considered for adsorption and the blocking diffusion. Depending on the active potential, distinct behavior such as the transformation of transients and limited diffusion can occur. Phase-space spectra are obtained, and synchronization has been developed to clarify the chaos leading to the cracking of palladium. By applying these different analytical tests for the restricted diffusion, it is possible to interpret the processes from the power spectra, autocorrelation function, or the divergence coefficient in the region of active potentials. Analyzers can detect flaws in this hydrogen diffusion process and suggest corrective measures.