Corrosion Resistance Of Aluminum Alloys Research Articles

Enhancing aesthetics, hardness and corrosion resistance of aluminum alloy via deposition of Al/Si/AlN coatings

Enhancing aesthetics, hardness and corrosion resistance of aluminum alloy via deposition of Al/Si/AlN coatings

PDA-modified sol-gel coating for long-lasting corrosion protection on Al alloy 3003

Within the realm of corrosion protection methods for Al alloys, sol-gel technique has garnered increasing attention. However, conventional sol-gel methodologies cannot provide adequate long-lasting corrosion protection to Al alloys when exposed to chloride-rich solutions. This paper introduces an innovative approach to substantially augment the corrosion resistance of aluminum alloys through utilization of polydopamine (PDA)-modified sol-gel films. Effort was made to fabricate a PDA-modified sol-gel coating and a systematic investigation was conducted thereof. Long-term corrosion performance of this coating in 3.5 wt.% NaCl solution was evaluated through electrochemical impedance spectroscopy (EIS). Results show that the low-frequency impedance of the PDA-modified sol-gel coating remains significantly high at 7.9 × 105 Ω·cm2, even after 36 d of immersion in 3.5 wt.% NaCl medium, indicative of excellent protective properties. It notably surpasses low-frequency impedance of the unmodified coating, which registers at 2.5 × 104 Ω·cm2. The incorporation of PDA into the sol-gel coating, facilitated by adsorption and diffusion mechanisms, serves to fill micrometer- and nanometer-scale defects of the coating, thereby markedly enhancing their compactness. Furthermore, despite its modest thickness of 9 μm, the PDA-modified coating exhibits enduring corrosion protection capabilities.

Optimization of tribological properties and corrosion resistance of MAO coatings on LY12 aluminum alloy by co-doping with graphite particles and in situ formation of zinc phosphate

Micro-arc oxidation (MAO) coatings can enhance the wear and corrosion resistance of aluminum alloys, but the high coefficient of friction and surface pores can lead to failure in the field. In this study, zinc acetate and graphite particles are introduced to the electrolyte to form corrosion-resistant and lubricating MAO coatings on the LY12 aluminum alloy. Zinc phosphate nanocrystals formed in situ are uniformly distributed in the amorphous coating, while the extrinsic graphite is mainly located in the amorphous structure. Compared to the aluminum alloy substrate, the friction coefficient of the optimal MAO coating decreases to ∼0.2, and the wear rate decreases by nearly 10 times. Zinc phosphate nanocrystals generated in situ in the coatings release Zn2+ during corrosion attack to cover the vulnerable weak corrosion areas around the pores. The corrosion resistance is improved significantly, as manifested by the increase of the corrosion potential from −1.290 V to −0.811 V and the decrease of the corrosion current density from 3.172 × 10−6 A cm−2 to 4.320 × 10−10 A cm−2. The co-doped MAO coatings have better wear and corrosion resistance and are more suitable than the LY12 alloy in many engineering applications.

Role of scandium addition to microstructure, corrosion resistance, and mechanical properties of AA7085/ZrB2+Al2O3 composites

The effect of varying amounts of scandium (Sc) on the mechanical performance and corrosion resistance of aluminum alloy (AA7085) composites reinforced with Zirconium diboride (ZrB2) and Aluminum oxide (Al2O3) nanoparticles was investigated. The specimens were made using an in-situ process with varying amounts of Sc up to 0.5 wt%, and their microstructural behavior, corrosion, and mechanical properties were explored in detail. Phase structural analysis revealed the successful incorporation of ZrB2 and Al2O3 into the matrix through in-situ synthesis, ranging from 30 to 61.7 nm. In addition, HRTEM and XRD analysis displays the Al3Zr prominence observed with 0.1 wt% Sc content, transforming to Al3(Sc, Zr) in the 0.3 wt% Sc composite, and finally becoming Al3Sc with 0.5 wt% Sc. Corrosion analysis revealed that the 0.3 wt% Sc composite exhibited fine Al3(Sc, Zr) precipitate phases that enhanced corrosion properties. The Sc addition leads to a significant improvement in the mechanical properties of AA7085/ZrB2+Al2O3 composites. The ultimate tensile strength of 678 ± 5 MPa for 0.5 wt% Sc under the hot rolled and T6 aged condition was achieved. The optimum content of Sc in AA7085/ZrB2+Al2O3 composites has identified both corrosion and mechanical properties enhancement at 0.3 wt% and 0.5 wt%, respectively.

Numerical and experimental studies on bending behavior of circular aluminium-concrete-steel double skin tubular cross-sections and bending capacity design approach

Considering the excellent corrosion resistance of aluminium alloy, a new-type aluminium-concrete-steel double skin tubular (ACSDST) member is proposed by replacing the outer steel tube of concrete-filled double skin steel tubular members with an aluminium alloy tube to improve structures' corrosion resistance and durability. Until now, no literature has been available on ACSDST cross-section in bending. This paper presents experimental and numerical investigations on the flexural behaviour of circular ACSDST cross-sections in bending. Broad parameters are examined in this research, including varying diameter-to-thickness ratios of the outer tube (20–120), hollow ratio (0.2–0.75), concrete compressive strength (30–70 MPa) and steel yield strength (235–355 MPa). The experimental results show that the final failure is controlled by the tensile rupture of aluminium alloy tubes, but it generally happens after the maximum moment, and the composite section behaves in good curvature ductility. The parametric analysis based on the developed finite element (FE) model discloses the different influences of diameter-to-thickness ratios of the outer tube, hollow ratio, and concrete and steel strengths on the bending moment capacity. Among them, the diameter-to-thickness ratio of the outer tube and hollow ratio significantly affect the bending moment capacity. The design equations for bending moment capacity are induced based on the plastic stress distribution method. Those equations are safe and accurate for the maximum moment (a widely used definition of bending moment capacity) within a certain range of parameters. However, a reduction factor 0.9 is proposed for the equations to predict the moment at a longitudinal flexural tensile strain of 1% (another widely used definition of bending moment capacity). Moreover, the cross-section slenderness limit for the compact ACSDST section is recommended based on the analysis of the experimental and FE results.

Study of tribological performance and corrosion resistance of aluminum alloy 6063 composites enhanced with a combination of silicon carbide and tungsten disulfide particles

This research explores the effects of wear on a 6063 aluminum alloy matrix combined with silicon carbide (SiC) and tungsten disulfide (WS2) particulates. Dry friction wear tests were conducted on three materials: pure 6063 aluminum alloy, a composite with 4 wt% SiC and 4 wt% WS2 reinforcement, and another composite with 6 wt% SiC and 4 wt% WS2 reinforcement. These materials were tested against AISI410 stainless steel discs under varying loads (10N, 20N, and 30N) and sliding rates (0.5, 1.0, and 1.5 ms−1) following a Taguchi L27 orthogonal experimental plan. Main effect graphs (S/N ratios) and ANOVA analysis were utilized to determine optimal parameter combinations, and confirmation tests were carried out to validate the Taguchi results. Scanning electron microscope (SEM) images of wear areas showed that incorporating SiC and WS2 significantly enhanced the wear resistance of the aluminum alloy. This indicates that incorporating SiC and WS2 reinforcement has the potential to enhance the wear resistance of aluminum alloys, making them suitable for applications such as piston rings in internal combustion engines, which is in line with the requirements of engine performance. Furthermore, potentiodynamic polarization studies evaluated the corrosion resistance of the Metal Matrix Composites AA6063 in 3.5% NaCl. Results indicated that the AA6063 + 6 wt% SiC + 4 wt% WS2 composite exhibited superior corrosion resistance compared to AA6063 alone.

A Critical Review of Anti-Corrosion Chemical Surface Treatment of Aluminum Alloys Used for Sports Equipment

Aluminum alloys with low-weight property are promising structure materials for sports equipment. Alloying element-rich second-phase particles create the risk of localized corrosion and result in failure of sports equipment. Chromate conversion coatings as conventional and successful surface treatments were employed to provide a thin but compact film against corrosion. However, chromate species were toxic and carcinogenic for human beings and this process has been highly restricted. In this sense, alternative processes such as trivalent chromium conversion coating with low environmental risk require better corrosion-resistant performance compared to chromate conversion coating. In addition, the closed-loop system of the chromate electroplating process has been used in Europe and the United States. This is also a sustainable process for surface treatment of aluminum alloys applied in sports equipment. The present paper aims to summarize the methods and types of different aluminum alloy surface treatments and compiles the effects of various surface treatments on the corrosion resistance of aluminum alloys. The eco-friendly application of aluminum alloys in the field of sports equipment may be facilitated in the future.

Synergistic mechanism of strengthening and toughening of tissue regulation response to Mg/Al composite laminates by hard plate accumulative roll bonding

The significance of light alloy in realizing the national strategy of energy saving and emission reduction and promoting the upgrading of the manufacturing industry is self-evident. Mg/Al composite laminates combine the lightweight of magnesium alloy and the plasticity and corrosion resistance of aluminum alloy. Traditional accumulative roll bonding technology relies on the advantage of introducing large deformation. Although high strength is obtained, it is often accompanied by a large loss of ductility, and there is a problem that it is difficult to balance strength and ductility. To solve this problem and optimize the process conditions, a new hard-plate accumulative roll bonding process is proposed in this paper, which is used to prepare high-performance Mg/Al composite plates, and the influence of forming temperature on the microstructure and mechanical properties of Mg matrix is studied. The results show that when the forming temperature is 350 °C, the properties of composite laminates are the best, the tensile strength can reach 243 MPa, the elongation is 14.7 %, and there are a lot of tearing edges and dimples on the fracture surface. At the same time, complete recrystallization can be realized at this temperature, and the opening of non-base slip can coordinate deformation stress, promote the dislocation slip, and reduce the dislocation density, SEM images show that there are no defects such as delamination at the interface, and a firm metallurgical bonding is achieved. It provides a new approach to the forming and manufacturing of high-quality lightweight heterogeneous composite laminates.

Study of structure formation and strength indicators of aluminum alloys when modified with dispersed compositions

Promising directions of modification of aluminum alloys are studied in the field of application of powder modifiers. The use of such modifiers facilitates the technological process, is environmentally safe, leads to a uniform distribution of the introduced compositions over the cross-section of the casting, which increases the strength, plastic properties of the alloys and their stability. Purpose. The purpose of the work is to increase the mechanical properties and corrosion resistance of aluminum alloys when modified with dispersed compositions. Methodology and materials. To achieve the goal, the tasks were set: to conduct a study of a complex of mechanical properties, necessary technological characteristics, corrosion resistance and structure of alloys before and after modification. Aluminum alloys of the Al-Si, Al–Mg–Sc systems, promising for nuclear power plants, have been proposed. The materials are offered for the production of cast aluminum alloys AL9 and deformed alloys 1571. Results and discussion. The modification of aluminum alloys with a complex nano-dispersion modifier based on the plasma chemical synthesis of Mg2Si and SiC is planned. The crushed grain of modified alloys is achieved by 1.5...2 times, the mechanical strength increases by 12...18% and the corrosion resistance grows too. The results of tests on general corrosion showed that modification with a complex modifier ZrC leads to an increase in the corrosion resistance of alloys due to a decrease in the corrosion rate. The corrosion rate of AL9 alloy in the modified state was reduced from 11.04 10-6 to 9.84 10-6 kg/m2 days, which is 18%. The mechanism of complex nano-disperse modifier in aluminum melt is proposed. Conclusions. The use of such modifiers facilitates the technological process, is environmentally safe, leads to a uniform distribution of introduced nanocomposites, which increases the strength of alloys and their stability. The achieved results showed the effectiveness of modifying aluminum alloys with nano-disperse compositions.

Bio-inspired Ti3C2Tx MXene composite coating for enhancing corrosion resistance of aluminum alloy in acidic environments

Aluminum alloy (Al alloy) suffers from severe corrosion in acidic solution. Two-dimensional (2D) MXene-based composite coatings show great prospects for corrosion protection on metals used in special conditions. The composite coatings still face challenges in complex functionalization and orientation control. In harsh conditions, the long-term ability and roles of MXene in corrosion protection are still not clear. Here, a bio-inspired myristic-calcium chloride-Ti3C2Tx MXene (MA + CaCl2 + MXene) composite coating is successfully prepared on aluminum alloy (Al alloy) by electrodeposition process. Electrochemical tests, surface morphology, and chemical composition are analyzed to investigate the corrosion resistance and protection mechanism of the MXene coating in acidic solution (0.5 M H2SO4 + 2 ppm HF). As a result, the incorporation of MXene can significantly reduce corrosion current density (7.498 × 10-8 A/cm2) by ∼ 5 orders of magnitude and impedance modulus at 0.01 Hz (|Z|0.01 Hz) value of the composite coating is 196.8 Ω·cm2, which is over 4 times higher than that of bare Al alloy (40.74 Ω·cm2) after immersion test for 72 h. Furthermore, the in-situ corrosion test confirms the enhanced corrosion resistance of the MA + CaCl2 + MXene composite coating. The MXene can increase coating thickness to 23.6 ± 0.4 μm, reduce porosity to (5.845 ± 1) × 10-5, decrease the diffusion coefficients of H+ to (1.587 ± 0.3) × 10-9 cm2/s, and enhance the adhesion of the coating to the substrate (the delamination time exceeds 5 h), thus providing improved anti-corrosion ability. This strategy opens up new prospects for construction of 2D MXene-based anti-corrosion coatings.

Rapid synthesis of organosilicon oxide thin films and post-curing for enhanced scratch and corrosion resistance of aluminum alloy

Organosilicon oxide (SiOxCy) film deposited onto flexible aluminum (Al) alloy AA1050 substrate by an atmospheric pressure plasma jet and combined with post-curing in air at 150–300 °C for 30 min, is investigated to highly improve the scratch and corrosion resistance of Al substrate from a presence scratching up to 6.4 % after first scratch test (against #0000 steel wool at 100 g loading) and a corrosion rate up to 3.73 mm/Yr after immersed for 12 h (against in PH2-3.5 wt% NaCl–HCl aqueous solution) for the original Al substrate to a thorough deficiency of scratching (0 %) up to 140 scratch tests and a corrosion rate up to 0.0066 mm/Yr for Al/SiOxCy. The enhanced scratch and corrosion resistance of Al/SiOxCy are proven to be greatly dependent on their film properties, and surface characteristics of nano SiOxCy films and post-cured in air at 150–300 °C.

Fabrication of multi‐scale TiC and stainless steel composite coatings via circular oscillating laser towards superior wear and corrosion resistance of aluminum alloy

The poor wear and corrosion resistance of aluminum alloys has led to the easy failure of surface performance. In this work, composite coatings of TiC/martensitic stainless steel (TiC/MSS) on aluminum alloy are fabricated by a novel approach of circular oscillating laser for enhanced surface performance of aluminum alloys. The oscillation of laser leads to dense microstructure, and nano/micro scale TiC particles are formed simultaneously. The structure of coatings transforms from dendritic to ring-like with the addition of TiC, and the hardness of the substrate is increased by 4.5–7.8 times. The main wear form of coatings is adhesive wear. The refinement of microstructure and formation of multi-scale TiC have given rise to an increase in the resistance of the coating to plastic deformation, which reduces the degree of adhesion and improves wear resistance. Besides, the barrier effect of TiC particles to the electrolyte solution in the passive film gives rise to the drop in corrosion current density. The Cr-rich stacking faults can provide nucleation sites for the formation and growth of passive films with high continuity and stability, thereby improving the corrosion resistance of the coatings. The superior anticorrosion and wear resistance properties of the composite coatings in this work have emphasized the merits of oscillating laser in fabricating high-performance coatings and would enlighten the design of more advanced composite coatings.

Исследование микродугового оксидирования как метода улучшения технических характеристик сплавов алюминия марки AA5086 и титана марки ВТ6

The article presents the promising field of micro-arc oxidation as a surface modification method with the purpose to improve the corrosion resistance of titanium, aluminum, aluminum alloys and composites. Micro-arc oxidation is an electrochemical process that forms a thick, hard and highly adhesive ceramic oxide layer on the metal surfaces, thereby providing excellent protective properties. This method of hardening the metal surface was used in production in the manufacture of parts from AA5086 and VT6 alloys for industrial fans operating in chemically hazardous facilities. When using micro-arc oxidation, the strength and wear resistance of the internal parts of the fan to aggressive medium was increased. By that increased the trouble-free operation time and reduced the likelihood of destruction of the internal parts of the fan, which subsequently made it safer for employees to operate the fans in close proximity to the work area. This work examines the corrosion resistance of aluminum alloys and composites, since the indicated materials are also widely used in various branches of industry. It also considers the role of alloying elements in influencing corrosion behavior, as well as the influence of microstructure and processing methods on corrosion resistance. In addition, the discussion extends to the corrosion behavior and protective measures for aluminum matrix composites, including the inclusion of reinforcing phases such as ceramic particles, fibers or nanoparticles. Throughout the article, the corrosion resistance of micro-arc oxidation treated surfaces, anodized aluminum layers, aluminum alloys and composites are critically assessed, analyzing the factors influencing their protective characteristics, such as the morphology, composition and thickness of the oxide layers, as well as environmental factors.

Ductile and Corrosion-Resistant Aluminum Alloy From Recycled Secondary Aluminum Scraps Containing Iron Impurities

Ductile and Corrosion-Resistant Aluminum Alloy From Recycled Secondary Aluminum Scraps Containing Iron Impurities

Study of functional perylene diimides for corrosion protection on aluminum alloy surfaces

BackgroundAluminum alloy is an active metal with light density and good ductility; However, due to the easy occurrence of metal corrosion, its application is limited. In order to improve the corrosion resistance of aluminum alloys, functional corrosion resistant coatings can be prepared through self-assembly technology to protect aluminum alloys. MethodsA bridged perylene diimide (PDI-E) molecule was designed and a PDI-E film was successfully prepared on the surface of aluminum alloy by self-assembly. The morphology and structure of the films were characterized by SEM, XPS, and FT-IR. In addition, electrochemical testing was conducted to explore the corrosion resistance of the film. Significant discoveryElectrochemical performance experiments have shown that the electrochemical impedance is two orders of magnitude higher than the aluminum alloy substrate, and the corrosion current density is reduced by two orders of magnitude, indicating that the film layer has good corrosion resistance. The theoretical calculation results indicate that the two ends of the bridge molecule can combine with the aluminum alloy to form a C-O-Al bond, which is consistent with the experimental results

Improving the wear resistance of aluminum by a nickel-filled anodized porous alumina layer

Anodizing is a widely used method for increasing the wear and corrosion resistance of aluminum alloys. However, it is known that the porous brittle alumina layer can easily crack during tribological stresses, which results in the detachment of large particles from the worn surface. Electroplating, on the other hand, can produce a compact ductile metallic coating with enough wear resistance, though a specific pretreatment like the zincate process is needed for an aluminum substrate. In this paper, a combination of the two methods, anodizing and electroplating, is applied on the surface of pure aluminum intending to improve the wear resistance. Anodizing was performed in oxalic acid by applying a constant current density of 2 A/dm2. The anodized samples were then immersed in phosphoric acid for up to 10 h to increase the diameter of the pores. Nickel electroplating was carried out on the anodized samples at a current density of 0.5 A/dm2 in a Watts solution. Cross-sectional studies show that there is an optimum pore widening time that establishes a good adhesion between nickel and anodic oxide layers, while the structure of the oxide film is largely preserved. Sliding wear tests were performed on the samples using a ball-on-disk reciprocating tribometer. The results show much higher wear life for all Ni/Al2O3 composite coatings as compared with the alumina layer. The maximum wear life was obtained for the sample etched for an optimum pore widening time of 4 h.

Construction of porous anodic oxide/Ce-MOFs film by induced electrodeposition and its corrosion resistance

Aluminum alloy has good expansion and low hardness. However, aluminum alloy is susceptible to corrosion in humid environments, limiting their application. In this experiment, we adopted an efficient and facile method to prepare porous anodic oxide (PAO) films and PAO/Ce-MOFs composite films. It can be characterized by SEM, EDS, FT-IR, XRD, XPS and other test methods. The corrosion resistance is studied by neutral salt spray test and electrochemical test. Electrochemical data show that the resistance of PAO/Ce-MOFs film is three orders of magnitude higher than that of aluminum alloy substrate, and the corrosion current density is three orders of magnitude lower than that of aluminum alloy substrate, reaching 1.621 × 10−8 A/cm2. The corrosion resistance efficiency is 99.92%. The salt spray experiment shows that the film can maintain the corrosion resistance for 30d. The results show that Ce-MOFs coating can effectively improve the corrosion resistance of aluminum alloy. Therefore, this study provides a new approach in the application of MOFs materials in the direction of anticorrosion.

Electrochemical and Economic Analysis of No-Rinse, “True-Cr-Free” Surface Conversion Coatings for a Green, Cost-Saving, Corrosion Protection of 8079 Aluminium Alloy

Increasing the corrosion resistance of aluminium alloys using surface treatments while reducing the processes’ environmental impact and saving natural resources has become an urgent need. Some companies that typically use pollutant substances in their process lines have started to test low-environmental-impact products. This paper shows the results obtained using two commercial products for the conversion coating of AA8079 rolled-samples: the first, rinse, containing CrIII (the so-called “Cr-free” products), the second one, no-rinse, utterly free of Cr, based on hexafluorotitanate and dihydrogen hexafluorozirconate. The bare conversion-coated, and organic-coating-covered samples were compared with each other, evaluating their corrosion resistance when immersed in NaCl 3.5 wt.% aqueous solution. The experimental results showed that the completely Cr-free no-rinse conversion coatings demonstrate performance comparable to that of the so-called “Cr-free”. In addition, a comparison of the amount of water used in the “rinse” and the “no-rinse” industrial process is reported. Finally, an estimation of the economic balance for the process is presented, considering the waste reduction to be disposed of and the water quantity used. The aim of this paper was to demonstrate that some commercial conversion-coating products, completely free of Cr and no-rinse, are available nowadays, showing good protective properties and low environmental-impact, while guaranteeing an economic saving which is not negligible.

Effects of aging treatment on the mechanical properties and corrosion resistance of an Al-Cu-Mg-Li alloy

In this paper, the effects of as-quenched, single aging, and double aging on the mechanical properties, microstructure, corrosion resistance, and electrochemical behavior of an Al-Cu-Mg-Li alloy were investigated. Most changes only improved the mechanical properties or corrosion resistance of aluminum alloy alone, and very few of them improved the mechanical properties or corrosion resistance at the same time. The results showed that double aging treatment improved the strength, hardness, and corrosion resistance of the alloy but decreased its elongation. During the aging treatment, the corrosion morphology of the alloy gradually transformed from pitting corrosion (as-quenched) to a combination of pitting corrosion and corrosion cracks (single aging) and finally to pitting corrosion (double aging). The fracture morphology gradually changed from an uniform distribution of a mixture of large and small dimples (as-quenched) to an intergranular fracture (double aging) as aging progressed. Transmission electron microscopy results showed that the T1 phase within grains and at grain boundaries (GBs) was different between the as-quenched and double aged states. In addition, a precipitate-free zone (PFZ) formed in the double aged state. The optimal process of Al-Li alloy was determined to be pre-aging at 100 ℃ for 4 h and final aging at 160 ℃ for 24 h.

Research on springback compensation for multi-point forming of corrosion-resistant aluminum alloy hyperbolic component

Springback is the reverse elastic deformation produced by the unloading process, which is a common phenomenon in the sheet metal stamping and forming process and affects the final forming accuracy of the part. Aiming at the problem of springback error in the multi-point forming process of hyperbolic component for ships, the springback phenomenon of hyperbolic component was studied by combining theoretical analysis, numerical simulation and forming test. The mechanical property parameters and stress-strain curves were obtained by tensile tests using a new corrosion-resistant aluminum alloy as the sheet material. The springback compensation method is introduced, the springback compensation formula based on surface curvature is derived, and the compensated mold surface is further corrected and fitted using the cubic B-sample method. The multi-point punch tooling was generated and modeled by the multi-point 3D modeling software MPFCAD and finite element software to simulate the multi-point forming and unloading springback process of the hyperbolic member. Multi-point forming tests were conducted on a multi-point forming press for corrosion-resistant aluminum alloy hyperbolic component, and the formed parts were checked for accuracy and error analysis by 3D scanning and GOM Inspect software. The results show that the springback compensation method used in this paper can effectively reduce the springback error in the multi-point forming process of corrosion-resistant aluminum alloy hyperbolic component, and the effect is very good.