Al Alloy Surface Research Articles

Easily Applicable Superhydrophobic Composite Coating with Improved Corrosion Resistance and Delayed Icing Properties

Mitigating the adverse effects of corrosion failure and low-temperature icing on aluminum (Al) alloy materials poses significant research challenges. The facile fabrication of bioinspired superhydrophobic materials offers a promising solution to the issues of corrosion and icing. In this study, we utilized laboratory-collected candle soot (CS), hydrophobic fumed SiO2, and epoxy resin (EP) to create a HF-SiO2@CS@EP superhydrophobic coating on Al alloy surfaces using a spray-coating technique. Various characterization techniques, including contact angle meter, high-speed camera, FE-SEM, EDS, FTIR, and XPS, were employed to investigate surface wettability, morphologies, and chemical compositions. Moreover, a 3.5 wt.% NaCl solution was used as a corrosive medium to evaluate the corrosion resistance of the uncoated and coated samples. The results show that the capacitive arc radius, charge transfer resistance, and low-frequency modulus of the coated Al alloy significantly increased, while the corrosion potential (Ecorr) shifted positively and the corrosion current (Icorr) decreased by two orders of magnitude, indicating improved corrosion resistance. Additionally, an investigation of ice formation on the coated Al alloy at −10 °C revealed that the freezing time was 4.75 times longer and the ice adhesion strength was one-fifth of the uncoated Al alloy substrate, demonstrating superior delayed icing and reduced ice adhesion strength performance.

Preparation of graphene/AlCoCrNiTiMox coatings by laser parameter optimization based on TRIZ theory and its application in extending the service life of surveying and mapping drones

During the use of surveying and mapping drones, their aluminum (Al) alloy body is prone to corrosion and has certain requirements for mechanical properties. In order to extend the service life of surveying and mapping drones, this study uses laser cladding technology to prepare graphene (Gr) reinforced AlCoCrNiTiMox high entropy alloys (HEAs) coatings on the Al alloy surface of the drone body. In order to optimize the laser preparation parameters, the Invention Problem Solving Theory (TRIZ) is introduced. By utilizing innovative tools such as physical contradictions, technical contradictions, and material field models of this theory, the preparation process parameters such as laser power, laser scanning speed, laser spot diameter were optimized. The microstructure of the coatings were analyzed using scanning electron microscope (SEM), transmission electron microscope (TEM), electron back scatter diffraction (EBSD), etc. The corrosion resistance, hardness and wear resistance of the coatings were tested. The experimental results show that the microstructure of Gr/AlCoCrNiTiMox alloy is mainly composed of equiaxed grains and molybdenum-chromium (Mo-Cr) precipitates. The Gr/AlCoCrNiTiMox HEAs exhibits excellent corrosion resistance in 0.5 mol/L H2SO4 solution. The corrosion resistance of alloys is related to their composition, the effects of Gr and Mo elements. Under the combined effects of solid solution strengthening, precipitation strengthening, Mo element and Gr, the mechanical properties of Gr/AlCoCrNiTiMox alloys are excellent. The hardness of Gr/AlCoCrNiTiMo0.1 and Gr/AlCoCrNiTiMo0.2 alloys are 685 HV and 736 HV, respectively, with average friction coefficients of 0.64 and 0.58, respectively. The effect of Mo element makes the grain size of Gr/AlCoCrNiTiMo0.2 alloy smaller than that of Gr/AlCoCrNiTiMo0.1 alloy, resulting in better mechanical properties and corrosion resistance. The research results indicate that laser cladding of Gr/AlCoCrNiTiMox coating on the Al alloy surface of drone fuselage provides assurance for extending its service life.

Caesalpinia crista seed is used as an eco-friendly inhibitor to prevent the corrosion of aluminium in hydrochloric acid solutions

This investigation delves into the inhibitory impact of Caesalpinia crista (Kanchaki) seed extract (CCE) on the corrosion of aluminium alloy (AA6061) at temperatures varying between 303 and 333K, employing Potentiodynamic Polarisation (PDP), Electrochemical Impedance Spectroscopy (EIS), and weight loss methodologies. Findings demonstrate that CCE extract effectively safeguards Al against corrosion, with efficacy increasing at higher concentrations. The observed inhibitory action exhibits a cathodic-type behavior across all concentrations and temperatures, aligning well with Langmuir isotherm. Notably, the highest level of inhibitory efficiency, reaching 96.87 ​%, is attained at a concentration of 2.0 ​g/L and a temperature of 303 ​K for 3 hours. Consistency is observed between the results obtained through EIS and PDP. A plausible mechanism for preventing corrosion in Al alloy is proposed. Surface analysis techniques, such as Atomic Force Microscopy (AFM) and Scanning Electron Microscopy/Energy Dispersive X-ray analysis (SEM/EDX), validate the adsorption of the inhibitor onto Al alloy surfaces. Morphological examinations corroborate electrochemical findings, confirming protection against uniform corrosion in HCl solutions. Additional analyses involve the computation of activation energy and thermodynamic parameters, with a thorough discussion of the results.

Effect of the alloying element Sc and Zr in 5B70 Al alloy on the microstructure, toughness and tribological properties of MAO ceramic film

The existence form of alloying element Sc and Zr in the micro arc oxidation (MAO) ceramic film on 5B70 Al alloy and their effects on the microstructure, fracture toughness, and tribological properties of the MAO ceramic film was investigated. The findings suggested that the Zr element primarily existed in the form of ZrO2, distributed around the Al2O3 phase. The Sc element remained spherical and dispersed in the form of Al3Sc in the ceramic film. The synergistic effect of ZrO2 and Al3Sc significantly improved the hardness, fracture toughness, and wear resistance of the dense layer in MAO ceramic film on 5B70 Al alloy. This provided theoretical basis and technical support for the development of high-performance MAO composite films on Al alloy surfaces.

Effects of the processing parameters and laser textures in friction stir spot welding of Al alloy and polyimide joints

In this paper, friction stir spot welding (FSSW) technology was introduced to join 7075 Al alloy to polyimide (PI) sheets. The effects of the FSSW parameters and laser textures on the microstructure and tensile shear load of the Al/PI joint were studied. The optimum FSSW parameters were the rotation speed of 2400 r/min, the plunge depth of 0.4 mm, the dwell time of 20 s, and the plunge speed of 10 mm/min. The tensile shear load of the joint increased owing to the laser textures in the Al alloy surface. Cross-sections showed that the mechanical locking was found between the Al alloy and PI. The XPS results revealed that no chemical bond were formed at the welding interface after laser textures. The joining mechanism of Al 7075 and PI was main the mechanical locking.

In-Depth Insight into Corrosion Inhibition Performance of Sweet Potato Leaf Extract as a Green and Efficient Inhibitor for 6N01 Al Alloy in the Seawater: Experimental and Theoretical Perspectives.

Corrosion protection of metal has become an important and urgent topic, which requires the development of an inexpensive, environmentally friendly, and highly efficient corrosion inhibitor. Herein, a sweet potato leaf extract (SPL) was obtained by a simple water-based extraction method and then as a green corrosion inhibitor for 6N01 Al alloy in the seawater was well investigated by the weight loss method and various electrochemical tests. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopies were carried out to investigate the compositions of SPL. The findings from the potentiodynamic polarization (PDP) curves suggest that SPL functions as a typical mixed-type corrosion inhibitor. Notably, the maximum corrosion inhibition efficiency reaches 94.6% following a 36 h immersion period at 25 °C. The adsorption behavior of SPL on the Al alloy surface belongs to the Langmuir adsorption isotherm. The Gibbs free energy value illustrates that the adsorption of SPL contains both physisorption and chemisorption. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) indicate that SPL is firmly attached to the Al alloy surface by making a protective layer, which can effectively inhibit the corrosion of the Al alloy in the seawater. Furthermore, quantum chemical calculations were applied to validate the chemical adsorption and elucidate the relationship between the electronic structure of the active components in SPL and their effectiveness in corrosion inhibition.

Dense Amorphous Passivation Layer Formed on Aluminum Alloy Surfaces by Femtosecond Laser-Assisted Oxygen-Rich Doping.

Aluminum (Al) alloy surfaces are prone to serious corrosion in humid and salt-laden environments, which promotes the development of numerous protective approaches. Although the amorphous state is more conducive to improve corrosion resistance compared with the crystalline state, it still faces coating design problems like insufficient adhesive strength and flaking-off tendency. Here, we propose a strategy of femtosecond laser-assisted oxygen-rich doping to in situ create a dense high-quality passivation layer on Al alloy surfaces. With respect to the femtosecond laser processing in traditional air ambience, the material surface modifications within the oxygen-rich environment demonstrate some distinctiveness. For the ridge area of the laser ablation grooves, the oxidation surface is separated into two layers: the outer region presents a loose and porous appearance similar to the observations in the air ambience, while the inner region exhibits complete and homogeneous oxidation, especially associated with the continuous distribution of the amorphous substance, in sharp contrast to the nanoscale discrete amorphous formation in the air case. Simultaneously, the high degree of material oxidization with the amorphous phase is also developed on the wallside area of the groove valleys, which is much different from the incomplete oxidation in the air ambience. As a result, the measured corrosion current decreases by 49 times to a value of Icorr = 1.19 × 10-10 A/cm2 relative to the laser treatment in the air environment. Such a method offers the prospect for elevating the anticorrosion performance of metal surfaces.

Mechanically Durable and Fluorine‐Free Ni–Cr Alloy‐Based Highly Hard Superhydrophobic Coating on Al Alloy

Superhydrophobic coatings, known for their water‐repelling properties, play an important role in corrosion resistance and self‐cleaning applications. This study addresses the pressing need for eco‐friendly and durable fabrication methods for metal surfaces, particularly Al alloys, recognized for their inherent low mechanical properties. The innovative electroplating technique successfully fabricates superhydrophobic coatings on Al alloy surfaces, incorporating a high‐hardness Ni–Cr alloys layer and a low‐surface‐energy stearic acid layer. The resulting coatings exhibit outstanding mechanical durability, corrosion resistance, and self‐cleaning capabilities. With a water contact angle of 165° and a corrosion protection efficiency of 98.6%, these coatings offer a substantial improvement over traditional methods. Moreover, the Leeb hardness of the coated alloy experiences an impressive 83% increase compared to pristine Al alloy. This universally applicable approach opens avenues for developing mechanically robust superhydrophobic coatings on various metallic substrates, with broad implications for engineering applications.

High corrosion-resistant octanoic acid vapor-phase modified Ce-LDH surface film of aluminum alloy

The cerium salt modified LDH coating (Ce-LDH coating) was produced on AA5052 Al alloy surface by in-situ hydrothermal synthesis. The vapor phase assembly of octanoic acid (OA) was adopted to improve the further hydrophobicity of Ce-LDH layer. The octanoic acid modified Ce-LDH coating (VOA-Ce-LDH coating) was successfully prepared on AA5052 Al alloy. It indicates that the VOA-Ce-LDH coating has excellent anti-corrosion protection with a protection efficiency of 96.95%. VOA-Ce-LDH coating contains two different layers. The outer layer is an octanoic acid (OA) vapor phase assembly layer and a Zn-Al LDH layer. The inner layer is Al(OH)3 (aluminum hydroxide) layer. The physical barrier layer of OA and the corrosion ion trapping function of LDH give the good anti-corrosion protection of the modified coating. This study is helpful for the development of vapor phase corrosion inhibitors and LDH coating for corrosion protection on metal materials.

Constructing quasi-vertical carbon nanotubes fiber bridging on aluminum alloy with micro-channels to improve adhesive bonding with carbon fiber reinforced polymer composites

The poor wettability and compatibility, and weak mechanical interaction of bonding interface are main concerns for adhesive bonding of aluminum (Al) alloy and carbon fiber reinforced polymer (CFRP) composite, limiting its high strength developing and industrialization. In this study, the united treatments of anodizing, chemical vapor deposition (CVD) and resin pre-coating (RPC) were adopted to construct the quasi-vertically distributed carbon nanotube (CNT) fiber bridging for reinforcing the adhesive bonding joints. The results exhibited that better surface properties including morphology, roughness and wettability were obtained after anodizing. CNTs could be in-situ grown via the novel CVD method in the channels or micro-cavities formed by anodizing treatment. Acetone-diluted epoxy resin solution enabled to flow into the root of micro-cavities or the gap of growing CNT fibers to reduce potential void defects. Single lap shear test results indicated that Al-CFRP composites treated by anodizing, CVD and RPC performed up to 136.1 % increment in strength compared to the base. While the original debonding failure on Al alloy surface was changed into the complete delamination failure of CFRP composites, verifying the stronger bonding interface and strength. Thus, the novel united treatments were effective and might be an alternative solution in developing high-performance Al-CFRP composites.

A self-regulated shielding layer induced by an electrolyte additive for alkaline Al-air batteries.

Aqueous Al-air batteries (AABs) are considered promising electrochemical energy devices due to their high-energy density, high-capacity density, and stable discharge voltage. However, the self-corrosion, passivation, and parasitic hydrogen precipitation side reactions in the aqueous electrolyte degrade the performance of these batteries, limiting their development. To overcome the problems related to the use of AABs, we introduce ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) as an additive to the alkaline electrolyte. EDTA-2Na adsorbs strongly to the Al anode interface creating a protective layer capable of inhibiting water-induced parasitic reactions. In fact, in the presence of the additive, the hydrogen evolution tests have shown that the hydrogen evolution rate decreased from 0.70 to 0.30 mL cm-2 min-1. In addition, the electrochemical tests indicated an inhibition efficiency of 55%, the full-cell discharge tests suggested an increase in the specific capacity density of the battery from 943.6 to 2381.7 mA h g-1 and the anode utilization increased from 31.6% to 80.9%, greatly improving the performance of the battery. Surface characterization of the Al alloy surface was also carried out to investigate the adsorption of EDTA-2Na on it. This electrolyte modification strategy provides a promising option for modulating the anode/electrolyte interface chemistry to achieve high-performance AAB.

Ultrathin Water-Responsive Zwitterionic Hydrogel Brush Coatings for Long-Term Corrosion Protection.

Preventing metal corrosion has usually been associated with water-repellent coatings that inhibit the penetration of aggressive chloride ions. Contrary to this conventional wisdom, we engineered ultrathin superhydrophilic zwitterionic hydrogel brushes rooted in a nanoporous anodic aluminum oxide (AAO) substrate that effectively hampered the adsorption of hydrated chloride ions (Cl-·H2O) on the Al alloy surface. The hydrogel brush coating enhanced corrosion resistance by 3 orders of magnitude, with corrosion current density declining from 1.518 to 1.567 × 10-3 μA cm-2. Despite suffering from long-term salt-spaying tests, zwitterionic hydrogel brush coating retained 2 orders of magnitude of corrosion resistance. Direct Raman spectroscopic evidence manifested that interfacial water comprised both highly ordered hydrogen-bonded water and disordered water containing hydrated Cl- ions. Under the hydration effect of zwitterionic hydrogel brushes, an interfacial disordered water structure dynamically transformed into a hydrogen-bonded water film. We correlated the structure and quantities of interfacial water with the corrosion current density and chloride adsorption. Hydrogen-bonded water improved by zwitterionic hydrogel brushes weakened the affinity and adsorption of hydrated Cl- ion water on the oxide film, resulting in excellent corrosion protection. Therefore, employing localized hydration tuning strategies, these findings are anticipated to generally empower ordered interfacial water to enhance metal corrosion resistance through precise interfacial engineering.

Nano-SiO2 based anti-corrosion superhydrophobic coating on Al alloy with mechanical stability, anti-pollution and self-cleaning properties

Improving the corrosion resistance of widely used Al alloys is important for expanding their industrial and marine applications. Structural fragility and preparation cost have always been key factors for restricting anticorrosive application of extensively-reported superhydrophobic surface. In order to try and fight that, combining with polyurethane (PU) adhesion agent, 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) was encapsulated around nano-SiO2 ceramics for robust coating in place of conventional structure preparation strategy on Al alloy surface. Such low-cost one-step air-spraying SiO2@PFDTES@PU coating was prepared by 0.03 g nano-SiO2 ceramics addition, 100 μL PFDTES and 0.25 g PU with the highest water contact angle of 168.34° ± 2.72°, a rolling angle of 4.02° ± 2.08°, and a propylene glycol oil contact angle of 156.52° ± 3.35°. FE-SEM, laser confocal microscopy, EDS and XPS were used to investigate micro-nano morphology and chemical composition of the coating. Meanwhile, the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements showed that as-prepared coating exhibited larger capacitive arc diameter, enhanced charge transfer resistance, larger |Z|0.01Hz value, positive shifting Ecorr and significantly reduced Icorr, thus demonstrating a significantly improved corrosion resistance. In addition, sandpaper friction experiment was used to evaluate the mechanical stability of the fabricated superhydrophobic coating. Ultimately, its resistance to solid/liquid contamination and self-cleaning ability were also systematically assessed. This work provides strong technical supports for industrial and marine applications for such low-cost, wear-resistant and anti-corrosion coating.

An effective micro-arc oxidation (MAO) treatment on aluminum alloy for stronger bonding joint with carbon fiber composites

The micro-arc oxidation (MAO) treatment was used in this study to modify aluminum (Al) alloys to improve bond strength with carbon fiber reinforced polymer (CFRP). Various porous surfaces of Al alloy with better hardness, roughness and wetting were created. Void defects were reduced via using resin pre-coating (RPC) technique to guide high-viscosity epoxy into the holes, CNTs fiber bridging was constructed to improve bonding interface and epoxy adhesive layer. Combined treatments of “Na2SiO3 + KOH solution” MAO, RPC and introducing CNTs on Al alloy surface yielded 21.34 MPa, up to 156.1% increment over base strength. Original de-bonding failure on Al alloy surface was altered into dominant fiber tearing failure of CFRP composites, indicating the reinforced bond strength and stronger adhesive joint. MAO was the first try and proved as a feasible treatment for bond strength improvement, which could provide an alternative to manufacture high-performance Al-CFRP composites in industrial production.

Crater array generated on Al alloy surface by nanosecond laser: Surface characteristics and bonding strength

The strength of aluminium (Al) alloy adhesive joints is critical for aerospace and automotive applications. This work uses an infrared nanosecond laser to create a crater array (CA) and thereby modify the substrate bonding area and enhance the strength of 7075-T6 Al alloy joints bonded by epoxy resin adhesives. We study how the parametrisation (crater overlap ratio β and pulse energy density Ф) of the CA affects the surface texture features (surface roughness Sa and fractional increase Sdr in surface area), wettability, chemical properties, and shear strength τ. The mechanism by which CA affects τ is revealed by the surface characteristics and failure modes. Sandblasted specimens were used as a reference. The results show that, for laser treatment, Sdr, Sa, and τ are closely related to β but not to Ф. When β = 30 % or 60 %, the CA surface is superhydrophilic. Regardless of β and Ф, the substrate absorbs carbon-containing pollutants from the air, so that the contact angle of the CA surface gradually increases over time until, 15 days after the laser treatment, the CA surface becomes hydrophobic. Zn, Cu, and Fe are uniformly distributed over the alloy surface, whereas C, O, Mg, and Al are unevenly distributed. The C content decreases with increasing β but is not correlated with Φ. The O content increases with the increasing β and Φ. When β = 30 %, the area of cohesive failure in the substrate bonding area is maximal. When β ≤ 0, the untreated area outside the craters is susceptible to adhesive failure. When β ≥ 60 %, the substrate bonding area is covered by a thin layer formed by molten residue, which is susceptible to substrate failure. Laser treatment is more effective than sandblasting in modifying the texture, wettability, and chemical properties of the bonding area, which can further improve the bonding strength. The maximum strength of the bonded joint obtained by laser treatment is 26.89 MPa at Φ = 21.6 J/cm2 and β = 30 %, which is 16.2 % stronger than sandblasting.

Effect of nanosecond pulsed laser parameters on texturing formation of metallic surface: Experiment and modelling

The laser ablation process is an indispensable tool in precision micromachining for fabricating micro/nanostructures with specific geometries and regulating physicochemical properties on target surfaces. However, the absence of studies on the effect of laser parameters on texturing formation and surface microstructure makes process control and the optimization of surface texturing challenging. In this study, a nanosecond pulsed laser process was employed to create the micro-texturing on the Al alloy surface, emphasizing the effect of process parameters on surficial grain structures and texturing formation. A three-dimensional (3D) heat transfer model based on the finite element (FE) method was developed to numerically visualize the shape-dimensional evolution of micro-texturing during laser ablation. A simplified but effective moving laser heat source model was proposed to predict the dynamic spatial and temporal distributions of heat generation and transfer. Material removal, which was dominated by surface evaporation in the pulsed laser process, was achieved using the element deletion method. Under various laser parameters, the model-predicted cross-sectional groove profiles agreed well with experimental measurements. In addition, the effects of laser power and scanning speed on the groove morphologies were investigated. The experimental findings and numerical models established in this study will provide guidance for precisely controlling pulsed laser parameters to achieve desired texturing structures and dimensions.

A high corrosion-resistant waterborne epoxy resin coating improved by addition of multi-interface structured zinc phosphate particles

In the present study, a three-dimensional multi-interface structured zinc phosphate particle with large specific surface area was prepared by regulating the zinc phosphate crystal growth process, which was applied to develop a waterborne epoxy resin coating with better corrosion resistance. The results reveal that the multi-interface structured zinc phosphate particles could well coalesce with epoxy resin. Compared with the waterborne coating doped with and without two-dimensional zinc phosphate sheets, the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating has highest corrosion potential, lowest corrosion current density and the highest low-frequency impedance, which indicates the obvious benefits of multi-interface structured zinc phosphate particles on corrosion resistance. Moreover, the electrochemical properties tests on the waterborne epoxy resin coatings immersed in salt solution for 3000 h demonstrate that the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating almost has no changes but the other waterborne epoxy resin coatings decrease obviously. The surface characterization on the corroded waterborne epoxy resin coatings reveal that the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating possesses the relative integrated surface, while the inner corrosion has occurred in other coatings. The waterborne epoxy resin coatings with different additives sprayed on Al alloy surface could obtain the adhesion strength between 6.21 and 6.81 MPa, and the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating possesses the maximum value. Even after the salt solution immersion for 3000 h, the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating still remains the adhesion strength above 6.21 MPa. Such excellent corrosion resistance should be ascribed to the cooperation of strengthened physical inhibition effect, decreased polar channel and complexation reaction by multi-interface structured zinc phosphate particles.

Facile Fabrication of High‐White and Robust Superhydrophobic Ni/Al2O3 Composite Coating on Al Alloy

This work presents a facile method to fabricate high‐white and robust superhydrophobic film on Al alloy surface. Ni/Al2O3 film with appropriate roughness and high‐white surface is constructed on the Al alloy by a simple chemical bath method via placing the Al alloy into the Ni2+ aqueous solution. Then the surface energy is reduced by spin‐coating the stearic acid (STA) to achieve excellent superhydrophobicity. As expected, the reflectivity, self‐cleaning, corrosion resistivity, and mechanical durability of Al alloy after modification have all displayed dramatic enhancements. The reflectance of the modified Al alloy is far above the pristine Al alloy at all wavelengths (200–2,000 nm). This high‐white film with remarkable reflectivity can effectively reduce its surface temperature and improve visibility in practical applications. Finally, a champion water contact angle of 161° and corrosion resistivity of 97.6% are attained by coating Ni/Al2O3‐STA composite film on Al alloy. The Leeb hardness of superhydrophobic film‐coated Al alloy is enhanced from 325 to 461 after coating superhydrophobic film on Al alloy. This work provides a framework for the development of superhydrophobic Al alloy with high‐whiteness and robustness.

Influence of synergistic effect of phosphate on corrosion resistance of self-assembled superhydrophobic composite film on 6061 aluminum alloy surfaces

Aluminum (Al) alloys are used in a wide range of applications due to their advantages. However, the existing corrosion protection methods have insufficient protection ability and cannot achieve long-term protection. In this paper, reactive protective film on the surface of aluminum alloys using 1-hydroxyethyl-1,1-diphosphonic acid (HEDP) molecules. Then, Lauric acid/Graphene (LA/rGO) film is used to prepared on the surface of HEDP film. SEM, XRD, EDS, Raman, XPS and WCA were conducted to analyze physical and chemical features of coatings. The total resistance of the film reaches 1.0 × 1020 Ω·cm2, in a salt spray test using 5wt% NaCl as the corrosion medium, corrosion spots appeared on day 28 with a corrosion inhibition efficiency of 99.99%. Theoretical studies with quantum chemical calculations have shown that HEDP/LA/rGO composite films can be adsorbed on Al alloy surfaces through P-O-Al and P-O-C chemical bonding. The influence of phosphate synergistic effect on the corrosion resistance of the self-assembled superhydrophobic composite film on the surface of 6061 aluminum alloy is discussed. This study presents a scientific and innovative design concept to develop coatings with excellent corrosion protection for aluminum alloy, and then extend their application to certain areas.

Improved anti-adhesive wear performance of rail/armature pair via interfacial energy modulation for electromagnetic launching applications

The prevention of adhesive wear between rail (made of high-strength Cu alloy) and armature (made of 7075 Al alloy) in the electromagnetic launching system is challenging due to the strong adhesion forces that arise from the interaction of asperities. Here, we propose a novel approach to enhance the anti-adhesive wear performance of rail through interfacial energy modulation between rail/armature pair for electromagnetic launching applications. Our findings indicate that the interfacial energy of the rail/armature pair can be significantly reduced by magnetron sputtering a W thin film onto the Al alloy surface. A lower coefficient of friction and a substantial alleviation in adhesion and mechanical damage of the Cu alloy are thus obtained. Molecular dynamics simulations reveal that the immiscibility and low interfacial energy of the Cu/W pair result in the formation of an amorphous interfacial layer during friction, facilitating countermotion at the contacting surfaces, thus in turn enables the low friction. The concept proposed in this work is further validated by real electromagnetic launching tests.