Aluminum Alloy Surface Research Articles

Stability of Supehydrophobic Layers Formed by Organic Acids on the Surface of Aluminum Alloy 6063

The paper discusses the possibility of obtaining a uniformly inhomogeneous surface of aluminum alloy 6063 as a result of alkaline etching and laser processing. Further surface treatment with ethanol solutions of octadecylphosphonic (ODPA) and stearic acids leads to its superhydrophobization (SHP). The study of the degradation kinetics of SHP coatings in water and under conditions of neutral salt spray showed the high stability of ODPA films obtained on a laser-textured surface with an irregularities height of 9.82 μm. X-ray photoelectron spectroscopy (XPS) results showed that ODPA is chemisorbed on the alloy surface. High corrosion resistance of the surface with superhydrophobic layers confirmed by polarization measurements, electrochemical impedance spectroscopy (EIS) and corrosion tests.

Study on removal mechanism of oxide film in direct current straight polarity tungsten arc welding of aluminum alloy

The Direct Current Straight Polarity (DCSP) TIG welding process of 2219 aluminum alloy was realized by removing oxide film on aluminum alloy surface with the activating flux. The effect of activating flux removing 2219 aluminum alloy surface anode oxide film and welding slag distribution morphology under the action of welding arc were analyzed. The results showed that the activating flux can effectively remove the anode oxide film, and welding slag with discontinuous floccules was distributed on the basic surface of aluminum, which was easy to remove. The difference in thermal expansion coefficient between Al and Al2O3 oxide films caused Al2O3 oxide films to crack under the action of high-temperature electric arc in TIG welding, but the oxide films cannot be removed. However, the weld surface coated with fluoride activating flux, fluoride can permeate between the oxide film and the aluminum matrix from the place where the oxide film cracked, causing defects at the film/matrix interface, which was conducive to peeling off the oxide film on the weld surface.

Particle Generation from Aluminum Alloy Surfaces Irradiated by 355nm Pulsed Laser and Multi-shots Laser Pretreatment Method at Low Fluences

The studies focus on particle generation from aluminium alloy surfaces irradiated by a Q switched Nd:YAG laser at 355 nm wavelength at low fluencies. The particles number increase with laser fluence but reduces with pulse number. The average initial threshold laser fluence for particles generation is 26.64 mJ/cm2. Larger particle with a diameter more than 5μm are found for fluencies above 76.54 mJ/cm2. After 40 pulsed laser shots at 72 mJ/cm2, it can effectively reduce the generation of metal particles. Our results demonstrated that 7075 aluminum alloy has the best laser resistance and the method of multi-shots laser pretreatment can reduced the generated particles by 76.92%. The SEM results shows that laser pretreatment process lead the passivation effct which smoothed the microstructure on the initial surface. The XPS results shows that zinc aluminate was generated during laser pretreatment process which has good thermodynamic properties. This study has important value for reducing metal particle contamination due to laser irradiation on metal surface in high power laser facilities and improving the service life of optical components.

Influence of tartaric‐sulfuric acid anodic film on four‐point bending fatigue behavior of AA 7050‐T7451 samples

AbstractTartaric–sulfuric acid (TSA) anodizing is an electrochemical process used for generating an anodic layer on the surface of aluminum alloys for aerospace applications. It must provide corrosion resistance and ensure no detrimental effect on the required fatigue properties for structural applications. This work aimed at analyzing the properties of the anodic layer and evaluating its influence on the fatigue behavior of the AA 7050‐T7451. The film properties were analyzed using optical and scanning electron microscopies. The surface residual stress (SRS) field in the as‐machined and anodized conditions was evaluated by the X‐ray diffraction technique.The results showed that TSA induces an appreciable reduction in the fatigue life, especially at lower values of stress amplitude, due to the presence of defects at the interface between the substrate and the anodic film. No correlation was observed between the presence of the anodic layer and the development of a tensile SRS field.

Effect of sintering routes on CIP/EIP – Al2O3 composite magnetic abrasive for chemo-mechanical magneto-rheological finishing of aluminium 6061

In magnetorheological fluid-based finishing processes, the lower gripping of abrasives in between ferromagnetic particle’s chain structure limits its finishing speed, resulting in a lower material removal rate and desired surface standard. In addition, tool ageing has significantly impacted these finishing processes at a higher speed. To improve the efficiency of finishing processes, composite magnetic abrasives are fabricated by using powder metallurgy techniques via both microwave and conventional processing (sintering) routes. Comparison studies were performed on these samples based on ferromagnetic materials (CIPs and EIPs) used and sintering at 950°C under fixed element composition. A newly advanced chemo-mechanical magneto-rheological finishing (CMMRF) process for aluminium alloy surface polishing was also proposed, combining mechanical abrasion and chemical action for the performance evaluation of composite magnetic abrasives. Most notably, the microwave processed composite magnetic abrasive outperformed conventionally processed samples in terms of magnetic and rheological properties. The composite magnetic abrasives significantly increased the rate of material removal from the metal surface while reducing the tool ageing effect. The surface profile and observation show that a nearly defect-free surface was produced at higher speeds using these composite magnetic abrasives compared to simply mixed abrasives based results.

Surface Roughening Behavior of the 6063-T4 Aluminum Alloy during Quasi-in Situ Uniaxial Stretching.

Owing to orange-peel defects, the industrial application of light alloy structural members is significantly restricted. In this study, a quasi-in situ axial tensile experiment was conducted on a 6063-T4 aluminum alloy sample. The surface morphology and microstructure evolution of the tagged area were scanned simultaneously using laser scanning confocal microscopy and electron backscattered diffraction, and the surface roughening behavior of the polycrystal aluminum alloy surface, caused by deformation, was quantitatively analyzed. As the concave–convex features at the surface appear in pairs with increasing global strain, the width of the concave features increases, whereas that of the convex features decreases gradually, resulting in the initially increasing surface roughness, which subsequently remains unchanged. During the stretching process, the small-sized grains in the 37~102 μm range show weak strain localization and the highest coordination of deformation. The deformation mode of medium-sized grains in the 114–270 μm range tends to grain deflection, and others tend to slip.

The effect of surface functional groups on the wettability of graphene oxide coated alumina substrate: Molecular dynamics simulations

In this article, molecular dynamic simulation was used to simulate the wetting process of graphene oxide coated alumina substrate. By changing the density of hydroxyl and epoxy groups on the surface of graphene oxide, the influence mechanism of two functional groups on the wetting process of water molecules was explored. From the simulation results, the increase of hydroxyl density can enhance the wettability of the substrate and reduce the wettability angle from 64.32° to 54.20°. By calculating the formation of the hydrogen bond in the wetting process, it is found that hydroxyl can significantly raise the hydrogen bond lifetime in the system. This increasing effect is particularly prominent in the observation of the hydrogen bond between water molecules and graphene oxide. The hydrogen bond lifetime increases from 2.20 ps to 12.77 ps. The result also reflects the reason why hydroxyl increases the wettability of the substrate. In addition, the increase of hydroxyl density also brings changes in hydrogen bond behavior and the number of hydrogen bonds. Under the condition of high epoxy density, most of the hydrogen bonds between water molecules and the substrate exist in the form of single hydrogen bonds, and the number is small. When the hydroxyl density increases, double-hydrogen bond, triple-hydrogen bond and single hydrogen bond appear in the model. In this process, the number of hydrogen bonds between the water droplet and the substrate is also increasing. Temperature is an important influence on the formation and lifetime of the hydrogen bond. High temperatures can promote the formation of the hydrogen bond between alumina and water molecules. In addition, it can also decrease the lifetime of all types of hydrogen bonds. Through the free energy perturbation theory, we get the free energy of different models in the wetting process. The results show that high hydroxyl density can improve the free energy of the wetting process, reduce the ability of spontaneous desorption and increase the stability of wetting. High temperatures can reduce the free energy and lead to the occurrence of desorption behavior. This article reveals the wetting mechanism of water molecules on graphene oxide coated alumina substrate, mainly reveals the influence of hydrogen bond and the change of free energy in the wetting process, which lays a theoretical foundation for the application of graphene oxide wetted coating on the aluminum alloy surface.

Design and superhydrophobic performance analysis of the rectangular-groove microstructure coated by nanocoatings

Nanocoatings and microstructure fabrication are two key methods to obtain superhydrophobic surfaces. However, the robustness of the nanocoating surfaces is weak and the post-processing of the microstructure surfaces is complicated, and neither of them is ideal for practical useable surfaces. This paper integrates two process technologies and manufactures a rectangular-groove microstructure coated by nanocoatings to obtain a robust superhydrophobic surface. Microscale rectangular groove structures are periodically etched on the surfaces of aluminum alloy by wire electric discharge machine (WEDM), then the nanocoatings were uniformly sprayed on the surfaces of the microstructure. The robustness and superhydrophobicity of the microstructure surfaces with nanocoatings are verified by surface wettability, robustness, weather resistance and chemical durability experiments. Experimental results indicate that microstructure surfaces with nanocoatings are more robust than smooth aluminum alloy surfaces sprayed by nanocoatings. The hydrophobic properties of the nanocoated microstructure surfaces are also much better than that of the uncoated microstructure surfaces.

Study the Influence of CNTs Deposited by Laser on the Surface of Al 2024 Alloy

Laser powder deposition (LPD) has been relied on to improve the surface properties of materials. Nowadays, an excellent reinforcement for aluminum and aluminum alloys could be carbon nanotubes (CNTs). The surface of aluminum alloy 2024 (Al Cu4Mg1) is coated with double-walled and multiwalled carbon nanotubes (DWCNTs, MWCNTs) using laser preplaced powder deposition with pulsed Nd:YAG to evaluate its effect on enhancing hardness and corrosion resistance. The laser power, pulse duration, scanning speed, and frequency, were controlled to complete this task. Since the best DWCNT deposited layer was obtained at the optimal process conditions, the Vickers micro-hardness and corrosion resistance of the coated Al 2024 surface improved in the readouts. The results showed that DWCNT improved specific essential surface attributes, namely hardness, abrasive wear resistance, and corrosion resistance, more than MWCNTs, according to the findings. Although MWCNTs have less penetration, their dispersion on the surface is superior to DWCNTs.

The influences of internal interactions and functional groups on the adsorption of graphene and graphene oxide with alumina substrate

Molecular dynamics is used to simulate the adsorption process of graphene and graphene oxide fragments with different sizes on the (0001) crystal plane of Al2O3. The results reveal that the influence of internal interaction and functional groups on graphene and graphene oxide adsorbed by the alumina surface. From the atomic simulation, it can be found that the Coulomb interaction between graphene and the substrate can enhance the interaction between graphene oxide and the substrate after oxidation. It also promotes the spontaneous adsorption of graphene oxide to the substrate, and its influence on the process is much greater than that of the van der Waals force interaction. Before graphene was oxidized, the Coulomb interaction and van der Waals force interaction inhibited the desorption of graphene, but the Coulomb interaction was relatively weak. In addition, the increase of the size of graphene and graphene oxide can reduce the adhesion energy and desorption free energy, resulting in the instability of adsorption state, which is more unfavorable to the occurrence of the adsorption process. In graphene oxide, the oxidized carbon atom bears most of the potential energy and induces the instability of the structure. Its three functional groups, carboxyl, hydroxyl and epoxy, play a role in reducing the overall potential energy of graphene oxide and stabilizing the structure of graphene. Therefore, compared with pristine graphene, graphene oxide with a high degree of oxidation can form a much stable coating on the alumina substrate. By means of multiscale modelling and simulation, this article may theoretically contribute to the application of graphene coating on the aluminum alloy surface and gives guiding opinions for enhancing the strength of graphene coating.

Microstructure and tribological behavior of plasma spray Ni60 alloy coating deposited on ZL109 aluminum alloy substrate

This paper investigated the microstructure and tribological behavior of Ni60 alloy coating prepared on the surface of aluminum alloy (ZL109) by plasma spray. The ANSYS software was applied to compare the deformation and temperature of nickel-based alloy coating deposited on aluminum alloy piston with the thickness of 300 µm, 400 µm and 500 µm. X-ry diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) were used to characterize the phase, microstructure and chemical composition of Ni60 alloy coating. Besides, fractal theory was used to study the geometric morphology of materials. The tribological properties of the coating were investigated under oil-lubrication at 100 °C through the circular cyclic test with Si3N4. The result shows that the piston skirt deformation was the smallest when the coating thickness was 300 µm. Multiple phases such as chromium carbide and Ni3Fe phases were contained in the coating, and Si element was dispersed in the Ni60 alloy powders with the form of silicon oxide, which enhanced the hardness and oxidation resistance of the coating. The porosity of the coatings prepared under three power conditions (P = 40 kW, P = 50 kW and P = 45 kW) were 1.58%, 1.47% and 0.97%, respectively. When the load increased from 80 N to 100 N, the depth and width of the wear scar increased and the wear volume added from 1.54 × 108 μm3 to 3.45 × 108 μm3. The friction coefficient of the coating increased with the increment of load. By comparison, the coating with moderate spraying power has less weight loss and better wear resistance under higher wear load.

Research Progress and Challenges in Laser-Controlled Cleaning of Aluminum Alloy Surfaces.

Aluminum alloys have been widely utilized in automobiles, aircraft, building structures, and high-speed railways industries due to their excellent structural and mechanical properties. Surface oxide film removal prior to aluminum alloy welding and old paint removal prior to repainting aluminum alloy surfaces are critical factors in ensuring the welding quality and service life of aluminum alloy products. Because of its unique advantages, such as environmental protection and precision control, laser-controlled cleaning has great application potential as a surface cleaning technology in removing oxide films and paint layers on aluminum alloy surfaces. In this paper, the mechanism of laser cleaning of oxide films and paint layers on aluminum alloy is discussed. Furthermore, the impact of various processing parameters such as laser beam power, energy density, scanning speed, and so on is analyzed in detail. After laser cleaning, the corrosion resistance, welding performance, adhesive performance, and other properties of the aluminum alloy are optimized. This paper also discusses several real-time detection technologies for laser cleaning. A summary and the development trend are provided at the end of the paper.

Wear Investigation of Aluminum Alloy Surface Layers Fabricated through Friction Stir Welding Method

In this research paper, an effort was made to investigate the dry sliding wear rate of friction stir welded AA6262/AA5456 composite performed by the Taguchi approach. Wear experiments are carried out by selecting suitable process parameters such as load (LD), sliding speed (SS), and sliding distance (SE) to recognize the individual and combination effects of parameters. Orthogonal array L27 mode is applied to make numbers of experiments to find the extreme and minimum wear amount. The experimental works are conducted on Pin on Disc (POD) apparatus and measured the weight of samples before and after test for calculating wear rate (WR) and then various analyses are performed such as ANOVA, interaction plot between parameters, and regression model with support of MINITAB software. The results revealed that maximum wear rate is found as 0.01215 mm3/Nm at LD of 50 N, SE of 600 m, and SS of 4 m/s, whereas minimum 0.00414 mm3/Nm at the grouping process parameters which are LD of 30 N, SE of 400 m, and SS of 6 m/s. From the observation of ANOVA, the most significant factor is identified as load, followed by sliding distance, sliding speed, and combination of each parameter. The load is considered as main parameter which contributes about 83.75% to achieve the maximum wear rate of developed AA6262/5456 composites. The contribution of sliding distance and speed are 3.75% and 1.85%, respectively.

Study on the superhydrophilic modification and enhanced corrosion resistance method of aluminum alloy distillation desalination tubes

In low temperature multi-effect distillation (LT-MED) seawater desalination system, the (super-)hydrophilic surface modification of aluminum alloy distillation desalination tube is effective in improving the performance of the desalination system and reducing the cost. However, the poor corrosion resistance of desalination tubes under (super-)hydrophilic surface modification is a bottleneck that limits the application of desalination tubes. This research breaks this technical bottleneck and proposes a simple, economical and industrially applicable method that jointly enhances hydrophilicity and corrosion resistance on aluminum alloy distillation desalination tubes. This method combines a concentrated anodizing electrolyte, pyrophosphoric acid, with an eco-friendly corrosion inhibitor, Na2MoO4, and prepares a superhydrophilic anodic oxide film with substantially enhanced corrosion resistance. The research shows that the concentration of Na2MoO4 in electrolyte plays a crucial role in the corrosion resistance of the superhydrophilic anodic oxide films: under the condition of ensuring the superhydrophilic surface of aluminum alloy (contact angle <5°), as Na2MoO4 concentration (0– 0.5 mol/L) increases, the higher the concentration of Na2MoO4 in the electrolyte, the better the corrosion resistance of the prepared superhydrophilic anodic oxide film. When adding 0.5 mol/L Na2MoO4 to 70 wt% pyrophosphoric acid electrolyte, compared with the superhydrophilic anodic oxide film without the addition of Na2MoO4, the prepared superhydrophilic film has its corrosion potential increased by 0.451 V, corrosion current density reduced by nearly four times, and corrosion inhibition efficiency increased from 25 % to 80 %. This research reveals the mechanism by which the corrosion inhibitor Na2MoO4 enhances the corrosion resistance of superhydrophilic anodic oxide film through adsorption of the porous layer, thickening of the barrier layer and Mo(+VI) incorporating. This paper provides a new idea and method for developing aluminum alloy desalination tubes with both stable superhydrophilicity and excellent corrosion resistance.

Laser-Induced Slippery Liquid-Infused Surfaces with Anticorrosion and Wear Resistance Properties on Aluminum Alloy Substrates.

Slippery liquid-infused surfaces (SLISs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and wear resistance. In this work, we used a simple laser processing technology to prepare a SLIS on the aluminum alloy (7075) surface. The superhydrophobicities of the modified surface and the oil film formed by liquid injection make the corrosive medium difficult to directly contact the surface and thus have a significant effect on corrosion resistance. The water and oil repellent SLIS exhibits durable corrosion resistance and excellent tribological properties compared with the SHS. The anticorrosion and wear resistance performances provided by the composite film have been assessed by multiple methods including the electrochemical test, immersion test, and friction wear test. The results indicate that compared to the bare surface, laser-ablated surface (LAS), and fluoroalkyl silane-modified SHS, the SLIS composite coating has better corrosion resistance and wear resistance, which is of great significance to expand the potential applications of 7075 aluminum alloys. The work provides a research basis for expanding the practical application of SLISs in complex environments.

Combined use of blackbody and infrared radiation for accurate measurement of temperature field of aluminum alloys

Temperature is considered a critical factor in improving the quality of workpieces in the manufacturing of aluminum alloys. To improve the temperature measurement accuracy of aluminum alloys and realize on-line measurement, this paper proposes a method for measuring the temperature field of aluminum alloys with infrared radiation combined with blackbody spots calibration. Since the emissivity of aluminum alloys changes with the surface characteristics of an object, there is a certain difference between the directly measured temperature using the infrared thermal imager and the actual temperature of the aluminum alloy surface. For this purpose, a correction method of infrared radiation temperature field of aluminum alloy based on image mapping theory was established. The uniform and non-uniform temperature fields of the aluminum alloy workpiece were designed, and the temperature field of the aluminum alloy plate was reconstructed based on the image mapping theory and the blackbody spots temperature. The study reveals that accurate measurement of the temperature field of aluminum alloys can be achieved based on infrared radiation combined with blackbody spots online calibration, and the maximum error is 1.5 K. Therefore, the method is suitable for industrial applications of aluminum alloys where emissivity varies with temperature.

Effect of the overlap ratio on surface properties of 7B04 aluminum alloy for aviation during laser derusting

Due to the harsh service environment of military aircraft, aluminum alloy on aircraft is prone to corrosion. Maintenance personnel need better rust removal methods to ensure the smooth progress of the flight mission. In this paper, the rust layer on the surface of 7B04 aluminum alloy was cleaned by nanosecond pulsed laser and mechanical grinding. Then the effects on surface morphology, surface roughness, surface hardness, residual stress and corrosion resistance of aluminum alloy were analyzed to determine an improved derusting method and optimize laser cleaning parameter based on the overlap ratio (η). Results showed that mechanical grinding not only did not remove rust completely but also damaged the matrix. When the laser scanning speed was 5650 mm s−1, η was 80%, the rust of the sample was completely removed without damaging the matrix. At the same time, the hardness and corrosion resistance of surface were improved and the appropriate increase of roughness was conducive to the repair of surface coating. When the scanning speed increased and the overlap ratio decreased, there was rust residue which can not meet the requirements of rust removal. When the scanning speed decreased and the overlap ratio increased, the rust was completely removed and the corrosion resistance of the surface was enhanced, but it caused excessive ablation damage to the matrix. And the above two cases will increase the difficulty of coating repair.

Electrodeposition of silane/reduced graphene oxide nanocomposite on AA2024-T3 alloy with enhanced corrosion protection, chemical and mechanical stability

Hydrophobic silane/reduced graphene oxide (rGO) nanocomposites were successfully constructed on an AA2024-T3 aluminum alloy surface using a facile co-electrodeposition process. The composition and morphology were characterized by ATR-FTIR, XRD, Raman spectroscopy, EDX, XPS and SEM. The results revealed that the implanted GO nanosheets were partially reduced and successfully covalently bonded with silanol groups to fabricate a more compact and denser coating. Electrochemical measurements demonstrated that the electrodeposited silane/rGO nanocomposite markedly decreased the corrosion rate of the AA2024-T3 alloy in 3.5 wt% NaCl solution. The protection efficiency was maintained over 96% after 120 h of exposure, presenting excellent chemical stability. Meanwhile, a sand paper abrasion test was performed to evaluate the mechanical robustness and the contact angle was reduced by only 4.5° after 150 abrasion cycles. The excellent anti-corrosion property and mechanical robustness, along with the feasible electrodeposition procedure, show its great potential for industrial applications.

Mechanical property and structure of polycarbonate /aluminum alloy hybrid prepared by ultrasound-assisted hot-pressing technology

ABSTRACT Polycarbonate/aluminum alloy hybrids were prepared using a homemade ultrasound-assisted hot pressing molding (UAHPM) technique, and their properties and structures at the plastic-metal interface were also investigated. The aluminum alloy surface was chemically etched and anodized to form micron and nano-holes structures. The joint strength of 21.58 MPa was achieved at the optimum molding process by optimizing the process parameters of ultrasonic hot compression molding. The specific structure and morphology of the polycarbonate/aluminum hybrid material bonding layer were observed by field emission scanning electron microscopy (FE-SEM) using the ultrathin sectioning technique, and the plastic embedding depth reached about 3.8 µm under the optimal process conditions. X-ray photoelectron spectroscopy (XPS) analysis revealed that the bonding layer not only has a micro-nano interlocking structure but also forms an Al-O-C chemical bonding interaction. The plastic in the bonding layer was exposed by dissolving the aluminum alloy of the joint, and the filling form of the plastic in the micro-nanoholes was directly observed.

Improvement in signal sensitivity and repeatability using copper nanoparticle-enhanced laser-induced breakdown spectroscopy

In the present work, the sensitivity and repeatability of the emission spectra have been investigated using nano-enhanced laser-induced breakdown spectroscopy (NELIBS). The colloidal solution of copper nanoparticles was produced by using the laser ablation technique at the fundamental wavelength of Nd: YAG laser at 100 mJ and deposited on the surface of standard aluminum alloy in different concentrations. With varying laser irradiances (10 GW/cm2 to 35 GW/cm2) and nanoparticles surface concentration (6.4 μL/cm2 to 57.7 μL/cm2), emission spectra were acquired from laser-induced plasma. On average the signal enhancement up to 50 times was achieved at a laser irradiance of 28.3 GW/cm2 and at NPs concentration of 45 μL/cm2. A decrease in relative standard deviations (RSD) from 28% to 16% for manganese and 18% to 10% for aluminum emission lines was achieved at laser irradiance of 10.5 GW/cm2 and surface concentration of 19.2 μL/cm2.