Corrosion Of Aluminum Alloy Research Articles

New morpholino acetamide ligand's rare earth metal complexes through synthesis, structural, and theoretical studies. Effect of ligand on aluminum alloy corrosion inhibition

A series of new complexes of the general formula [Ln(L)Cl2]Cly·4H2O (Ln = Er and Ta) and [Yb(L)(H2O)2]Cl3, L = N,N'-((ethane-1,2-diylbis(sulfanediyl))bis(2,1-phenylene))bis-(2-morpholino-acetamide) were synthesized and characterized. The physical properties of these complexes were investigated including melting point, color, and percentage yield. Spectral and physico-analytical techniques collectively with elemental analyses were utilized to structurally elucidate the synthesized complexes. At room temperature, complexes exhibited similar solution absorption spectra in the UV–Vis region. As shown by thermal analysis, the complexes lose water molecules first, then anions, and finally ligand molecule, leaving a metal oxide residue. The complexes resulted from monomolar coordination of neutral tetradentate ligand through the two amide nitrogen and the two sulfur, with octahedral geometries. Ligand and its Ta(V) complex were structurally characterized by X-ray powder diffraction. Their optical band gaps demonstrated the ligand and complexes have semiconducting properties. Multiple bonding patterns were discovered in molecular docking simulations of the ligand against SARS-CoV-2 (6Y84) and E. coli DNA gyrase (5MMN). The binding energy of the complexes revealed active compounds capable of inhibiting SARS-CoV-2 and E. coli DNA gyrase. The antioxidant activity of the ligand and its Ln-complexes was investigated, yielding some surprising results. Finally, it is worthy to note that, the biochemical outcomes revealed that these complexes may be promising antibacterial agents. Aluminum alloys (AlSi) corrosion inhibition was investigated in 1 M HCl using potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). The inhibition efficiency was found to be 96.36 % at 500 ppm inhibitor in 1 M HCl.

Superior hydrogen production rate by corrosion of recycled aluminum alloys: Feeding a PEM fuel cell

Aluminum is one of the most versatile materials for the dynamic global economy due to its mechanical properties, recyclability, and lightweight. The production of hydrogen from aluminum via hydrolysis in alkaline media offers another advantage of it. Recycling the post-consumer aluminum scraps leads to the formation of some undesirable intermetallic particles which are not only detrimental to mechanical properties but also to repeated recycling. In this study, the hydrolysis performance of a recycled aluminum alloy was compared with that of the primarily produced one. The results showed that the Mg solutes at the grain boundaries (GBs), Fe-containing and Mg2Si particles, stress concentration around the GBs, and thickness of the passive layer can affect the hydrogen generation rate of the specimens. The specimens were also tested in a proton-exchange membrane fuel cell to evaluate their hydrogen generation performance. The recycled aluminum alloy that can increase the hydrogen yield significantly increases the power of PEMFC.

Corrosion of aircraft heritage: a comparison between modern and historic Duralumin alloys

The development of innovative solutions for the conservation and the protection of historic aircraft is a recent and important issue raised in the cultural heritage field and represents the goal of the PROCRAFT (Protection and Conservation of Heritage Aircraft) project. Assessing and documenting the constituent materials as well as their degradation state is necessary to determine and understand factors inducing aluminium alloy corrosion, in order to develop tailored conservation treatments and identify effective protective coatings. The first step of the project was the identification of the constituent materials of aircraft wrecks. Al-Cu-Mg alloys—Duralumin and Super Duralumin, with a higher content of Mg—were the most employed alloys for structural and non-structural parts. These materials undergo a wide range of alterations, amongst which pitting, exfoliation and galvanic corrosion.In the present work, results of the characterisation of wrecks from a North American Republic P-47D Thunderbolt, crashed in Italy in 1945, are reported and compared to wrecks from a French Breguet 765 Sahara n°504 64-PH, built in 1958. The constituent alloys resulted to be similar to the modern 2024 and 2017A alloy.In order to assess the representativeness of these modern alloys in simulating the corrosion behaviour of the historic ones, exfoliation susceptibility (ASTM G34) as well as non-destructive and destructive electrochemical tests in 0.1 M NaCl were carried out on both historic and modern alloys. These results contributed to the selection of representative substrates for the development of protective coatings as well as to the expansion of the dataset on composition and microstructure of historic Al alloys for aircraft.

Epoxy coating containing CoMOF@MBT metal-organic framework for active protection of aluminum alloy

A new cobalt-based metal-organic framework (CoMOF) was synthesized and subjected to comprehensive characterization employing a range of established techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal analyses. CoMOF was functionalized by loading mercaptobenzothiazole (MBT) onto CoMOF to fabricate CoMOF@MBT with anticorrosion properties. Polarization and immersion tests were employed to estimate the corrosion inhibition ability of CoMOF@MBT in NaCl medium. The results show that it inhibits corrosion of AA2024-T3 aluminum alloy when it is submerged in a NaCl solution with a pH of 3, yielding an inhibition efficiency of 87 %. Protective anticorrosion coatings were prepared by incorporating CoMOF@MBT particles into epoxy resin and coated on AA 2024-T3 substrate. Corrosion resistance of the protective coatings was assessed through the utilization of EIS and salt spray tests and the results show that scratched panels with coating containing CoMOF@MBT exhibit a slow decline in Rct values. It shows an Rct value of 1.45 × 104 Ω cm2 after 48 h of immersion in NaCl medium. The results demonstrated that incorporating CoMOF@MBT improves the capacity of epoxy coatings to withstand corrosion of AA2024-T3 panels in NaCl through the smart release of MBT molecules upon exposure to corrosive agents.

Experimental, computational, and theoretical studies on the corrosion inhibition potential of green Gongronema latifolium extract as corrosion inhibitor for aluminum alloy in HCl solutions

Gongronema latifolium (GL) leaves extract was studied as a potential corrosion inhibitor for AA3003 aluminum alloy immersed in 0.4, 0.75 and 1.10 M HCl solution at 302–322 K. Herein, gravimetric, thermometric, electrochemical techniques, density functional theory via DFT/molecular dynamics simulation (MDS), scanning electron microscope (SEM)/X-ray diffraction analysis (XRD) were employed to analyze the effect of GL leaves extract on AA3003 aluminum alloy corrosion. Excellent statistical and machine learning techniques such as the response surface methodology (RSM) and artificial neural network (ANN) were used for the optimization and modeling. The constituent compounds of the GL leaves extract and their chemical structures were identified using a standard approach like the gas chromatography-mass spectrometry (GC–MS). The GL leaves extract significantly retards AA3003 aluminum alloy corrosion and its efficacy was seen to increase with increase in the GL leaves concentration in the acid media. Maximum inhibition efficiency (IE%) of 84.15 %, 81.45 %, 86.83 % and 87.11 %, were obtained for the mass loss, thermometric, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) methods, respectively in 0.75 M HCl solution at 312 K and 1.3 g/L GL leaves extract concentration. The RSM recorded highest IE% of 81.30 % in 0.75 M HCl, 1.30 g/L GL leaves extract concentration, temperature of 312 K and immersion time of 12 h. The ANN and ANN-GA algorithm predicted optimum IE% of 84.5160 % and 88.4189 %, respectively in 0.75 M HCl solution, 1.3 g/L GL leaves extract concentration, temperature of 312 K and 12 h immersion time. SEM/XRD examination validated the adsorption of GL leaves extracts molecules onto the A3003 metal alloy surface. The results of GC–MS analysis established that GL leaves extract comprised of compounds possessing active molecules and functional groups responsible for the corrosion inhibition of the AA3003 aluminum alloy surface in HCl media. Electrochemical investigation revealed that the inhibitor functioned as mixed-type inhibitor. The statistical and theoretical analysis results correlated with experimental results and confirmed GL leaves extract as efficient corrosion inhibitor for AA3003 aluminum alloy submerged in HCl solution.

Effect of Aging Temperature on Pitting Corrosion of AA6063 Aluminum Alloy

Effect of Aging Temperature on Pitting Corrosion of AA6063 Aluminum Alloy

Corrosion inhibition of 8-HQ for AA5052 in 3 wt% NaCl solution in presence of trace Cu2+ ions: Electrochemical/surface studies, DFT/MD modeling

In this paper, the effect of Cu2+ ions on corrosion inhibition of 8-hydroxyquinoline (8-HQ) for AA5052 aluminum alloy in the simulated seawater solution has been studied by weight loss experiments, electrochemical measurements and surface analysis. 8-HQ inhibits the corrosion of AA5052 aluminum alloy in 3 wt% NaCl solutions very well, resulting in a positive shift in corrosion potential. The 0.01 mg/L of Cu2+ ions can deteriorate the corrosion inhibition of 8-HQ at low concentrations. This behavior is interpreted on the basis of deposition of copper by displacement on the defects of the corrosion inhibition film of 8-HQ. When the concentration of 8-HQ reached 5 mg/L, the presence of 0.01 mg/L Cu2+ ions increase the corrosion inhibition efficiency of 8-HQ by 6.27%. 8-HQ shows efficient inhibition at a relative high concentration, suggesting that the chelate formed by Cu2+ ions and 8-HQ can repair the defects of the 8-HQ inhibitive film on aluminum surface. The complex film would suppress the partial cathodic reaction and lead to the improved corrosion inhibition.

Corrosion and Protection of Synthetic Intermetallic Compounds and Bulk Aluminum Alloy Under Simulated Atmospheric Conditions

Aluminum alloy 7075-D6 is often used for aircraft parts and is thus exposed to atmospheric conditions. AA7075-D6 is susceptible to corrosion due to high Zn, Mg and Cu contents in the form of various intermetallic particles having more or less noble electrochemical potential regarding the matrix (1,2). Usually, corrosion of aluminum alloys is simulated using solutions of various concentrations of chloride ions. However, aircraft are exposed to atmospheric conditions, where Cl- is not the only pollutant. Namely, in industrial and urban areas, major inorganic species such as ammonium (NH4 +), sulfate (SO4 2−) and nitrate (NO3 −) ions are found in the form of NH4NO3 and (NH4)2SO4 (or NH4HSO4). Therefore, these should also be considered because they represent corrosive agents for many aluminum alloys (3). Corrosive conditions may be thus better simulated by the so-called dilute Harrisonʼs solution (DHS) (0.35 wt.% (NH4)2SO4 + 0.05 wt.% NaCl), which in addition to Cl− also contains SO4 2− and nitrate NO3 − reflecting the environmental and atmospheric conditions. The first part of our study was focused on the corrosion of AA7075-T6 in DHS and comparison with NaCl solution. In addition to AA7075-T6, major intermetallic compounds (IMCs) synthesized in bulk form to represent the major intermetallic constituents (Al2Cu, Al2CuMg, Al7Cu2Fe and MgZn2) were also investigated. For IMCs, electrochemical measurements were performed using a microcell, and a standard cell was used to study the bulk alloy.Bulk AA7075-T6 was less susceptible to corrosion in DHS than in chloride solution stemming from the beneficial presence of sulfate ions and lower chloride concentration. The susceptibility of IMCs to corrosion in DHS increased as Al2Cu < Al7Cu2Fe < Al2CuMg < MgZn2 due to the increased dissolution of Mg in the presence of ammonium ions. The relative nobility of IMCs was determined based on the galvanic current density.In the second part of our study, we addressed the role of cerium salts in the corrosion protection of AA7075-T6 in DHS. Cerium salts are non-toxic compounds and demonstrate corrosion inhibition by inhibiting redox reactions by forming a protective cerium-containing precipitated conversion layer (4). Ce salts acted as inhibitors for the alloy during 14-day testing, forming a Ce hydroxide layer. The degree of protection depended on the type of anion, being the highest for Ce acetate. For the IMC, however, inhibition by Ce salts did not occur during short measurements, indicating the importance of galvanic interaction with the alloy matrix in the inhibition, which was confirmed by long-term measurements of the alloy. Micro and macro approaches give essential information on the galvanic relation between the IMPs and Al matrix under different conditions in the presence and absence of different cerium salts or other inhibitions (5). This brought about valuable information concerning corrosion inhibition and synergism with other ions in the corrosion media. Figure. Schematic presentation of (a) effect of various anions (NH4 +, SO4 2 - and Cl-) in dilute Harrison’s solution, and (b) effect of cerium(III) cations and corresponding anions (Cl-, NO3 - and CH3COO-) on the surface of AA7075-T6. Corrosion inhibition due to the deposition of the cerium layer is presented in (c). The precipitation of Ce species proceeds mainly on the cathodic sites and progressively spreads over the alloy surface; meanwhile, the Mg and Al are slowly dissolved from the anodic sites.

Application of in-situ EIS to Galvanic Corrosion of Aluminum Alloy Coupled with High-Tensile Steel

Toward multi-materials for the weight reduction of automobile bodies, the light materials have been used in the automotive industry. However, it may pose serious issues for degradation due to the galvanic corrosion. In this study, an in-situ electrochemical impedance spectroscopy (in-situ EIS) 1-4 was applied to the evaluation of galvanic corrosion of aluminum alloy coupled with high-tensile steel. This method allows for the simultaneous measurement of impedance spectra of aluminum alloy and high-tensile steel.An electrochemical measurement was performed by a three-electrode system. The working electrode (WE) was an aluminum alloy plate, the counter electrode (CE) was a high-tensile steel plate. The reference electrode (RE) was a saturated KCl-Ag/AgCl (SSE), which was set near the WE and CE. To simulate the galvanic corrosion environment of automotive materials, the aluminum alloy plate and high-tensile steel plate are set face-to-face. The distance of both electrodes was about 100 μm. The 3D impedance measurement was carried out for 2 weeks. In this measurement, the potential difference between the WE and the CE was set to 0 V to simulate galvanic corrosion 5. The frequency range was 10 kHz to 0.1 Hz at 5 frequencies per decade and AC potential amplitude was 10 mV. The electrochemical cell was placed in the temperature and humidity chamber for the wet and dry cyclic corrosion test.The in-situ EIS was successfully carried out during the wet and dry cyclic corrosion test in the temperature and humidity chamber. The three-electrode system enables the simultaneous measurement of impedance of aluminum alloy plate - high-tensile steel plate (WE-CE), aluminum alloy plate (WE), and high-tensile steel (CE). In the wet condition, the capacitive loop and part of large loop in the high and low frequency ranges were observed in the instantaneous impedance of the aluminum alloy plate-high tensile strength plate (WE-CE) determined from 3D impedance 1-4 at arbitrary time. In this case, the instantaneous impedance of the aluminum alloy plate (WE) and high-tensile steel plate (CE) described the capacitive loop and part of large loop on the Nyquist diagram respectively. It was confirmed that the capacitive loop and part of large loop in the high and low frequency ranges observed in the instantaneous impedance of the aluminum alloy - high tensile strength (WE-CE) were related to the aluminum alloy plate (WE) and high tensile strength plate (CE), respectively. The galvanic corrosion behavior during the wet and dry cyclic corrosion test was investigated by evaluating the charge transfer resistance estimated from the instantaneous impedance of the aluminum alloy plate (WE) and high-tensile steel plate (CE) to discuss the time variation of the charge transfer resistance.

Resolving the Dependence of Aluminum Alloy Corrosion on Grain Orientation by Scanning Electrochemical Cell Microscopy

The study of grain-dependent corrosion behaviors of practical polycrystalline metals remains challenging due to the influences of other microstructural features, such as intermetallic particles and grain boundaries. In this work, we employed the oil-immersed scanning electrochemical cell microscopy (SECCM) to investigate the effect of grain orientations of a practical aluminum alloy AA7075-T73 on the surface electrochemical behaviors. Thousands of spatially resolved microscopic potentiodynamic polarization (PDP) measurements were performed, allowing the extraction of information only from grain interior areas excluding intermetallic particles and grain boundaries. The differences in the corrosion behaviors between grains were revealed. Cathodic currents exhibited a strong grain orientation dependence with a decreasing order of {101} > {001} > {111}, agreeing with the prediction from the order of atomic planar density. By contrast, the dependence of anodic currents on grain orientation was weak, and pitting was independent of grain orientation, which could be due to the limited mass transport of ions within the surface oxide film. This work highlights the capability of oil-immersed scanning electrochemical cell microscopy in resolving small electrochemical differences, which will greatly promote the study of grain-dependent behaviors of practical polycrystalline samples.

Biochemical and microbiological characterization of a thermotolerant bacterial consortium involved in the corrosion of Aluminum Alloy 7075.

Microorganisms can play a significant role in material corrosion, with bacterial biofilms as major participants in microbially influenced corrosion (MIC). The exact mechanisms by which this takes place are poorly understood, resulting in a scarcity of information regarding MIC detection and prevention. In this work, a consortium of moderately thermophilic bacteria isolated from a biofilm growing over aluminum alloy 7075 was characterized. Its effect over the alloy was evaluated on a 40-day period using Electron Microscopy, demonstrating acceleration of corrosion in comparison to the abiotic control. The bacterial consortium was biochemically and microbiologically characterized as an attempt to elucidate factors contributing to corrosion. Molecular analysis revealed that the consortium consisted mainly of members of the Bacillus genus, with lower abundance of other genera such as Thermoanaerobacterium, Anoxybacillus and Paenibacillus. The EPS polysaccharide presented mainly mannose, galactose, rhamnose and ribose. Our observations suggest that the acidification of the culture media resulting from bacterial metabolism acted as the main contributor to corrosion, hinting at an unspecific mechanism. The consortium was not sulfate-reducing, but it was found to produce hydrogen, which could also be a compounding factor for corrosion.

Experimental study on the effects of three alloying elements on the mechanical, corrosion and microstructural properties of aluminum alloys

Aluminum is widely used in industries such as automobile and aerospace due to its lightweight, but its pure form lacks sufficient strength and the properties of aluminum can be modified by adding alloying elements. This paper presents the effect of adding Magnesium (Mg), Copper (Cu), and Zinc (Zn) on the mechanical, microstructural, heat treatment properties, and corrosion behavior of aluminum-based alloys. The aluminum-based alloys were manufactured with varying percentages (1 %, 3 %, 5 %, 8 %, and 10 %) of the three alloying elements using sand casting. Tension, compression, Brinell hardness, and corrosion tests were conducted to examine the effect of these alloying elements on the alloys' properties. The tensile strength is improved significantly with the increase in alloying elements for all alloys but the compressive strength and hardness are improved for Al–Cu alloy only. After heat treatment, the hardness of Al–Mg alloy increased at 8 % and 10 % Mg content while the hardness of Al–Cu alloy decreased after heat treatment for all concentrations of Cu. The hardness of Al–Zn alloys remained unaffected by the heat treatment process. The corrosion rate is minimum for Al–Mg and it is maximum for Al–Cu alloys but at 10 % concentrations, the corrosion rate of Al–Mg alloy is higher than Al–Cu alloy. The microstructural observation before and after heat treatment revealed that the grain refinement occurred for Al–Mg and Al–Cu alloys but the microstructure remained unaffected for Al–Zn alloys. The outcomes of this study offer valuable insights into customizing the mechanical characteristics of aluminum-based alloys to suit particular applications.

Study of wear and corrosion resistance of ATO nanoparticle–doped micro‐arc oxide film layers

AbstractIn order to enhance the corrosion and wear resistance of aluminum alloys in complex and variable environments, an Al2O3 ceramic film was prepared on the surface of 7A04 aluminum alloy in a silicate electrolyte system using a micro‐arc oxidation technique. Subsequently, antimony tin oxide (ATO) nanoparticles were used to dope the micro‐arc oxidation film to enhance the protective properties of the 7A04 aluminum alloy. The structural characteristics of the film were investigated by examining the surface and cross‐sectional morphology and the composition of the physical phases. The results show that ATO nanoparticles can promote the micro‐arc oxidation reaction, improve the surface morphology of the film layer, increase the thickness of the film layer and the denseness after sintering, and enter the film layer in the form of melt wrapping, which plays a role in refining the grain. In the study of the wear resistance and corrosion resistance of ATO‐doped ceramic film layers, it was found that the introduction of ATO nanoparticles did not significantly improve the wear resistance of the micro‐arc oxide ceramic film layers but significantly improved the corrosion resistance of the film layers.

Microbial corrosion behavior and mechanism of 5A06 aluminum alloy under low dose proton radiation

Low-dose proton radiation is one of the important factors that have a major impact on microorganisms in spacecraft. In this paper, the changes in the life activity characteristics of Penicillium oxalate and its impact on the corrosion behavior and mechanism of 5A06 aluminum alloy under low-dose proton radiation have been reported. The results show that the survival rate of the fungus is only 24.8 % under the low radiation condition, but its growth rate is faster and the content of organic acid produced by the metabolism of the fungus is higher per unit. The fungal attachment area was deeper and corroded more severely. Electrochemical tests have shown that the corrosion rate of aluminum alloy is related to the organic acid content in the metabolic solution, so the accumulation of organic acids is considered the main reason for the sever and faster corrosion of 5A06 aluminum alloy under low radiation.

Impact of Deep Seawater on the Electrochemical Corrosion Performance of Hypoeutectic, Eutectic and Hypereutectic Al-Si Automotive Alloys

Corrosion of aluminum alloys is a significant concern for shipbuilders to ensure the longevity of ocean vessels and equipment. Hence, the study aims to evaluate the corrosion performance of Al-Si as automotive alloys with varying concentrations of Si in deep seawater using electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The surface condition prior to corrosion, as well as after corrosion, is analyzed using optical and scanning electron microscopy. The entire test is performed at an ambient condition. The results demonstrate that the corrosion resistance improves in alloys with increasing amounts of Si near the eutectic level, after which the corrosion protection deteriorates. Higher Si concentrations show higher values for polarization resistance and open circuit potential. In contrast, corrosion current and corrosion rate values decrease with increasing Si concentration up to eutectic composition. Si assists the formation of SiO2 and MgO films through Mg2Si intermetallics along with the Al2O3 on the surfaces, which aids in corrosion resistance. Optical and scanning electron micrographs reveal the presence of films on the surfaces after corrosion, which exhibit pits and pinholes on the surfaces of the alloys with lower Si concentrations. Hypereutectic alloy is affected by corrosion of its pinhole-like defects. The corresponding EDS analysis also confirms the protective layer of different oxides on the surfaces.

Corrosion behavior of AA5052 aluminum alloy in the presence of heavy metal ions in 3.5 % NaCl solution under negative pressure

Aluminum alloy heat exchange tube is attractive for the Low Temperature-Multi Effect Distillation (LT-MED) desalination device, for its low cost and excellent mechanical property. However, it is prone to galvanic coupling corrosion in presence of heavy metal ions. In this paper, the effect of Cu2+ and Fe3+ ions on the corrosion of aluminum alloy in 3.5 wt% NaCl solution under negative pressure is investigated by the weight-loss method and the electrochemical measurements. It shows that the operation pressure affects significantly the corrosion behavior of AA5052 aluminum alloy in presence of heavy metal ions. As the pressure decreases, the resistance of the aluminum alloy to corrosion increases markedly. The corrosion products formed under different operation pressure are detected by SEM, XRD analysis. It is found that the diffusion process of corrosion products from the aluminum alloy surface into the solution is prevented as the decrease of pressure, resulting in the formation of the passivation layer on the aluminum alloy surface. The decrease of pressure can effectively restrain the heavy metal ions to be adsorbed on the defects of the oxide layer and mitigate the corrosion of aluminum during the LT-MED desalination process.

Data Evaluation of the Protection Performance of Maize Husk Particulate Reinforcements on 1170 Aluminium Alloy Corrosion in Dilute Electrolytes

Maize husk (MH) particulates at wt.% composition of 5% and 10%, and particle sizes of 150 and 300 um were added to the microstructure of 1170 aluminium alloy (Al) and analysed for their effect on the corrosion resistance of the maize husk reinforced aluminium composites Al/MH in 3.5% NaCl, 0.00625 M H2SO4 and 3.5% NaCl/0.00625 M H2SO4 solution by weight loss method. Protection performance results obtained at 264 h of exposure shows the MH particulates significantly enhanced the corrosion resistance of the Al/MH at 5 wt.% comp./150 um particle size (45%) and 5% wt./300 um particle size (30%) in 3.5% NaCl solution at 264 h. In 0.00625% H2SO4 solution, MH particulates significantly weakened the corrosion resistance of the Al/MH composites at all MH wt.% comp./particle sizes. Protection performance data at 264 h varied from-58.77% to 8.77 % which are significantly below the threshold 20% protection performance values. However, in 3.5% NaCl/0.00625% H2SO4, protection performance data above 20% threshold was obtained for Al/MH composites at 10% wt. comp./300 um particle size, 5% wt. comp./150 um particle size and 10% wt. comp./300 um particle sizes (22.58%, 38.71% and 29.03%). Results from ANOVA statistical method shows MH particulate wt.% comp./particle size is the important determinant factors influencing the protection performance results of Al/MH composites compared to exposure time with statistical relevance factor values of 36.53%, 77.98% and 18% from the electrolytes. The proportion of data above 20% protection performance for CB and CS particulates in 3.5% NaCl solution is 0% at margins of error of 0%. The corresponding values in 0.05 M H2SO4 solution are 15.18% and 15.32% at margins of error of 40% and 43% while the values from 3.5% NaCl/0.05 M H2SO4 solution are 14.78% and 15.5% at margins of error of 35% and 50%. The proportion of data above 20% protection performance for Al/MH composite in 3.5% NaCl solution is 30% at margins of error of 14.2%. The corresponding values in 0.00625 M H2SO4 solution are 15% at margins of error of 15.42% while the values from 3.5% NaCl/0.00625 M H2SO4 solution are 63% at margins of error of 15%.

Long-time irradiation effect on corrosion behavior of aluminum alloy in pool water of low-power research reactor

This study conducted an evaluation of the corrosion behavior of an aluminum alloy utilized in the Isfahan Miniature Neutron Source Reactor (MNSR). The component analyzed, dry channel (DC), had been exposed to radiation for 12 years in a water environment within the reactor pool since its installation. To determine the effect of radiation on the corrosion of the LT-21 aluminum alloy used in the DC, different parts of the pipe were sampled and various tests were performed. These tests included mechanical strengths (impact, and micro-hardening), XRD, TEM, SEM–EDS, and potentiodynamic polarization (PDP). The parameters measured included corrosion potential, corrosion rate, changes in microscopic structure, and mechanical properties of the aluminum alloy along the entire length of the DC. The neutron and gamma dose distribution along the height of the DC, which was 540 cm, was calculated to determine the correlation between the dose distribution and observed corrosion. The study found that the corrosion mechanisms were complex and resulted from the simultaneous presence of the DC in the pool water and radiation from the reactor core. The observed results are presented and discussed in this study.

Effect of h-BN nanoparticles incorporation on the anti-corrosion and anti-wear properties of micro-arc oxidation coatings on 2024 aluminum alloy

Micro-arc oxidation (MAO) coatings are recognized for their protective capabilities, yet their inherent porosity and defects limit broader applications. In this study, we aimed to rectify these limitations and enhance their performance by integrating hexagonal boron nitride (h-BN) nanoparticles into the MAO coatings. This work investigates the influence of h-BN concentration on the structure and properties of MAO coatings on 2024 aluminum alloy substrate. The results indicate that h-BN integration diminishes porosity and roughness, while improving hardness, adhesion, and corrosion and wear resistance. The corrosion current density (Icorr) of the most effective composite coatings is approximately 1% of the 2024 aluminum alloy substrate and 10% of undoped MAO coatings. Wear tests demonstrate the significant self-lubricating effect of the h-BN distributed in the coating, with the coefficient of friction (COF) of the most abrasion-resistant coating after h-BN doping being 67% of the undoped coating. During MAO, h-BN is uniformly incorporated into the coatings via diffusion and electrophoretic migration. The two-dimensional structure of h-BN in the coatings effectively blocks micro-defects, delays corrosive substance penetration, and enables self-lubrication. Conversely, excessive h-BN concentrations can instigate agglomeration and performance degradation. Optimum corrosion resistance is achieved with an h-BN concentration of 2.5 g/L, while the best wear resistance is attained at 10 g/L. The study suggests that h-BN-doped MAO coatings present substantial potential for applications necessitating high corrosion and wear resistance in aluminum alloys.

Study on filiform corrosion of A356 aluminum alloy under an organic coating

Due to its excellent performance, aluminum alloys are frequently used in wheels, but the corrosion of aluminum alloy wheels is still a major problem to be further studied. To understand the corrosion of wheels, it is important to consider the role of the organic coating in the corrosion process. Meanwhile, it is also meaningful to find an effective method to remove the organic coating properly to investigate the corrosion products under the organic coating. In this paper, the corrosion status of the A356 aluminum alloy substrate under an organic coating was observed firstly; lipid solutions such as NMP solution and butyl acrylate solution were used to remove the coating, and comparative experiments were carried out by controlling factors such as the soaking temperature, time, composition of solution etc. To find out the optimized soaking method to remove the organic coating; finally, the morphology of the localized corrosion on the aluminum alloy surface and the composition and structure of the corrosion products on the aluminum alloy substrate were analyzed. Results show that the corrosion products mainly contain ZrO2, Zr3O2F8, AlO(OH), and Al2O3. The corrosion process prefers to initiate at the defects where the coating and the substrate are not tightly bonded. This work shows the corrosion behavior of the aluminum alloy under an organic coating and provides a useful method to remove the organic coating from the aluminum alloy substrate effectively, and the results can be valuable for the understanding and mitigation of metal corrosion under an organic coating.