This study delved into the potential application of Platanus acerifolia leaf extract (PALE) as an environmentally benign corrosion inhibitor. Evaluation of corrosion inhibition was conducted using ...electrochemical methods, field emission scanning electron microscopy equipped with energy dispersive spectrometer. The results reveal that PALE offers efficient protection for Q235 steel across the temperature range of 298 K–318 K, achieving a maximum corrosion inhibition efficiency of approximately 93%. Furthermore, Density functional theory (DFT) calculations and molecular dynamics (MD) simulations were performed to elucidate the spontaneous and stable adsorption of PALE molecules onto the surface of Q235 steel. This adsorption impedes the diffusion of corrosive substances towards the steel surface, thereby endowing Q235 steel with robust corrosion resistance.
Amorphous carbon coatings by various physical vapor deposition (PVD) have been widely attempted for enhancing both anti-wear and corrosion resistance of bulk materials used in harsh marine ...environments. However, PVD coatings are apt to be worn due to the existence of growth defects mostly like macro-size nodular particles. In this work, we deliberately fabricated the SiO2 nanoparticles with a size of 200 nm as nodular defects in Cr and graphite-like carbon (Cr/GLC) multilayer coatings, and the dependence of tribocorrosion behavior of coating on the nodular defects was focused by the comprehensively tribological and electrochemical tests. The results showed that introducing SiO2 nodular particles could not degrade the mechanical properties of Cr/GLC coating, but significantly accelerated both the abrasive wear in early sliding-stage under dry friction and the corrosive failure in chloride solution. Particularly, once the tribocorrosion tests in 3.5 wt.% NaCl solution were conducted for the Cr/GLC coating with nodular defects, the distinct ploughing damage originated from abrasive wear promoted the localized spallation of coatings, which thereafter enabled the easy water wedging along spallation for the substantial catastrophe of coatings. The present observations could evident the importance to fabricate the defect-free protective coatings required for harsh tribocorrosion applications.
•AA2198-T851 is a potential substitute for AA2524-T3 with higher pitting resistance.•AA7081-T73511 is more prone to pitting corrosion than the AA7050-T7451.•Cathodic Al7Cu2Fe particles promote ...dissolution of adjacent 7XXX matrix.
The 2XXX and 7XXX series aluminium alloys are commonly used in aircraft applications where high strength-to-weight ratios are required. The present study aims to compare the corrosion resistance of two novel alloys developed for aircraft industry (AA2198-T851 and 7081-T73511) to that presented by the alternative base alloys (AA2524-T3 and 7050-T7451, respectively). Results indicate that AA2198-T851 may show a superior corrosion performance compared to AA2524-T3, being a potential candidate for its replacement, due to best mechanical properties. In what concerns the 7081-T73511, its resistance to pitting corrosion may be lower than for the base line alloy 7050-T7451.
Microscopic aspects of electrochemical reactions in a B10 Cu-Ni alloy/2205 duplex stainless steel (DSS) galvanic couple immersed in NaCl solution were investigated by electrochemical noise (EN) ...technique, scanning kelvin probe force microscopy (SKPFM), scanning vibrating electrode technology (SVET) as well as by scanning electron microscopy (SEM) method. Wavelet analysis by EN technique and microscopic characterization showed that the galvanic corrosion process can be divided into five detail stages. SKPFM and SEM observations revealed that the B10 Cu-Ni alloy/2205 DSS is a small-scale B10/ferrite/austenitic galvanic corrosion system that reduces the resistance of 2205 DSS to pitting attack.
•Galvanic corrosion of Cu-Ni alloy/2205 DSS couple was analyzed.•Pitting corrosion was observed on the surface of cathodic 2205 DSS in the galvanic system.•The galvanic corrosion process can be divided into five stages by wavelet analysis.•More accurate corrosion mechanism can be revealed by EN analysis.
Display omitted
•A simple one-step preparation of inhibitor-loaded mesoporous SiO2 nanocontainers was designed.•The new one-step method was efficient, energy-saving and organic solvents-free compared ...with traditional multi-step preparations.•The resultant nanocontainers had high uptake of inhibitor (∼16 wt.%) and possessed pH-responsive inhibitor release property.•The coating incorporated with the nanocontainers significantly improved the corrosion resistance of copper substrate.
We present a simple one-step method of preparing inhibitor-loaded mesoporous silica nanocontainers without extra steps such as template removal or inhibitors loading. The synthetic method is based on the high solubility of organic inhibitors in hydrophobic cores of template micelles. The resultant inhibitor (benzotriazole) and cetyltrimethyl ammonium bromide (CTAB) co-loaded silica nanocontainers had high uptake of inhibitor (∼16 wt.%) and possessed H+ ion-responsive inhibitor release property. When examined by scanning vibrating electrode technique, the coating doped with these nanocontainers exhibits effective corrosion protection property. These results suggest that the one-step synthetic method was efficient, energy-saving and organic solvents-free among others.
Laser-cleaned surface of hot-rolled AA7024-T4 alloy exhibited higher corrosion resistance in 3.5 wt.% NaCl solution than the as-received, due to the removal of the original less protective oxide ...layer consisting of MgO and MgAl2O4 and formation of more protective oxide layer containing Al2O3 and MgO.
Display omitted
•Laser cleaning removed the original oxide layer comprising of MgO+MgAl2O4.•Laser cleaning induced a formation of oxide layer consisting of Al2O3+MgO.•Laser-cleaned surface exhibited higher corrosion resistance than the as-received.•Newly formed oxide film by laser cleaning offered better protection against corrosion.
Laser cleaning has been considered as a promising technique for the preparation of aluminium alloy surfaces prior to joining and welding and has been practically used in the automotive industry. The process is based on laser ablation to remove surface contaminations and aluminium oxides. However the change of surface chemistry and oxide status may affect corrosion behaviour of aluminium alloys. Until now, no work has been reported on the corrosion characteristics of laser cleaned metallic surfaces. In this study, we investigated the corrosion behaviour of laser-cleaned AA7024-T4 aluminium alloy using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The results showed that the laser-cleaned surface exhibited higher corrosion resistance in 3.5 wt.% NaCl solution than as-received hot-rolled alloy, with significant increase in impedance and decrease in capacitance, while SVET revealed that the active anodic points appeared on the as-received surface were not presented on the laser-cleaned surfaces. Such corrosion behaviours were correlated to the change of surface oxide status measured by glow discharge optical emission spectrometry (GDOES) and X-ray photoelectron spectroscopy (XPS). It was suggested that the removal of the original less protective oxide layer consisting of MgO and MgAl2O4 on the as-received surfaces and the newly formed more protective oxide layer containing mainly Al2O3 and MgO by laser cleaning were responsible for the improvement of the corrosion performance.
Display omitted
•Reactive sputtering was shown advantageous for producing Nb2O5 thin film.•Nb2O5 coating improved the corrosion resistance of the 2524-T3 alloy.•Nb2O5 coating improved the wear ...resistance of the 2524-T3 alloy.
This study focuses on the surface modification of 2524-T3 Al alloy substrates, highly prospective in aeronautical sector, by niobium oxide films employing reactive sputtering technique. A set of Nb2O5 thin films was obtained and characterized by various techniques including AFM, SEM, EDX, FTIR and XPS. After the morphological and structural characterization of the thin films, electrochemical and micro-abrasive wear tests were performed. The results of FTIR are not conclusive regarding the possible valences in the chemical structure of the thin film, such as Nb2O5 or NbO2, whereas XPS results only indicate the presence of Nb2O5. The EIS spectra indicate that both the bare alloy and the Nb2O5 covered material were suffering pitting corrosion, although the obtained parameters indicate that the coating is expected to increase the corrosion resistance of the material, reducing the severity of the pitting attack. Localised tests demonstrated that Nb2O5 coating was able to delay the onset of corrosion process and significantly improve corrosion resistance of alloy 2524-T3 Al alloy. The 2524-T3 Al alloy containing the Nb2O5 coating presented greater wear resistance than bare material, with reduction in the wear rate, under a mixed wear mode by rolling and scratching in both materials.
•SVET shows the galvanic corrosion for an aluminium/copper model in NaCl solutions.•SVET depicts the inhibitive actions of benzotriazole and cerium chloride.•Benzotriazole rapidly reacts with copper ...surfaces, but inhibition is non-persistent.•Cerium ions react with the hydroxyl ions, blocking the copper surface after 46h.•A synergistic inhibitive effect is achieved by combining benzotriazole and cerium salt.
An aluminium/copper galvanic coupling model suitable for Scanning Vibrating Electrode Technique (SVET) analysis was elaborated with the aim of simulating a galvanic couple characteristic of AA 2024. The inhibitive effects brought by benzotriazole (BTA) and cerium chloride (CeCl3) on the Al/Cu model were evaluated, separately and combined, in neutral aerated sodium chloride solutions. A positive synergistic effect was revealed yielding permanent corrosion protection for 46h of immersion. Complementary techniques such as UV spectrophotometry and ToF-SIMS were employed, respectively, to investigate the decomposition of BTA molecules and to confirm the chemical composition of a combined BTA-based/Cerium-based layer.
In this work the protective effect of layered double hydroxide (LDH) films directly grown on the surface of 2024-T3 aluminium alloy is investigated using electrochemical impedance spectroscopy (EIS) ...and the scanning vibrating electrode technique (SVET). The SVET results focused on the localised nature of the corrosion process and are in agreement with the global response measured by EIS. Furthermore, the evolution of active corrosion protection rendered by LDH films is surveyed at microscale for the first time for long immersion periods in NaCl solution and in the presence of induced defects. The quantitative information provided by SVET is discussed and a parameter to describe the degree of corrosion localisation is introduced based on LDH systems.
Display omitted
•Propolis is an efficient green corrosion inhibitor for bronze surface.•The inhibitive effectiveness of propolis on bronze is time-dependent.•The main organic constituents of propolis ...sample were identified by HPLC-DAD.•The adsorption of propolis on bronze surface obeys Langmuir isotherm.
In the present work, the inhibitive action of natural propolis on bronze corrosion in a weakly acidic solution containing Na2SO4 and NaHCO3 at pH 5 was evaluated using multiscale electrochemical techniques, namely potentiodynamic polarization, electrochemical impedance spectroscopy and scanning vibrating electrode technique measurements. The major constituents of propolis were identified by HPLC. Surface characterization was performed by SEM-EDX and AFM analysis. Experiments were performed as a function of the propolis concentration and immersion time in the corrosive electrolyte. The obtained results showed that propolis presents good anticorrosive properties on bronze, acting as a mixed-type inhibitor, but its protective effectiveness is time-dependent. The highest inhibiting efficiency of 98.9% was obtained in the presence of 100ppm propolis, after about 12h of exposure to inhibitor-containing electrolyte through the stabilization of Cu2O on the bronze surface. The inhibitive properties of propolis on bronze corrosion are likely due to the adsorption of its main constituents (flavonoids and phenolic compounds), through the oxygen atoms in their functional groups and aromatic rings, which have been evidenced by FT-IR spectra. The adsorption of propolis on bronze was found to follow Langmuir adsorption isotherm.
PDF
