Aluminum Alloy Substrate Research Articles

Assessment of non-uniform residual stress field of the thermal sprayed stainless steel coatings on aluminium substrates by the integral hole drilling method

Thermal spray is one of the most used techniques to produce coatings on structural materials. Such coatings are used as protection against high temperatures, corrosion, erosion and wear. The combined action of high pressures, temperatures and spraying conditions give rise to non-uniform residual stresses. The latter plays an important role in coating design and process parameters optimization. The present work highlights the influence of coatings thickness on the evolution of residual stresses in layered materials. Therefore, thick stainless steel coatings (ASTM 301) of different thicknesses are manufactured by wire arc spraying on aluminium alloy substrates (ASTM 2017A). For a better bond strength, a Ni–Al bond coat is first deposited. Furthermore, a numerically supported hole drilling strain gage method for residual stress field evaluation is proposed. Required calibration coefficients, for the strain–stress transformation formalism based on the integral method, are computed through finite element calculations using Abaqus software. The results indicate that the maximum residual stresses, for all thicknesses, are tensile and range from 140 to 275 MPa. The bond coat does not seem to affect the stress field. Also, it was found that the mean equivalent Von-Mises stress decreases with increasing coating thickness; hence reducing the interfacial adhesion energy of the sprayed materials.

Characterization of bonding quality of a cold-sprayed deposit by laser resonant ultrasound spectroscopy

Resonant ultrasound spectroscopy was utilized to determine the mechanical properties of a planar interface between a cold-sprayed iron deposit and an aluminum alloy substrate. The measurements were done at room temperature and with a thermal cycle from room temperature to 500 °C. The properties of the interface were assessed by analyzing the resonant frequencies of a sandwich-like sample by means of a numerical model. While the as-sprayed deposit at the room temperature exhibited a perfect adhesion to the substrate, the thermal cycle led to deterioration of the properties due to precipitation of FeAl3 along the interface and subsequent cracking. The modal analysis enabled localization of the damage zone along the interfaces and simulating its temperature evolution during the cooling run.

Covalent surface modification of LY12 aluminum alloy surface by self-assembly dodecyl phosphate film towards corrosion protection

The goal of this work was to prepare a layer of dodecyl phosphate (DDPO4) film on LY12 aluminum alloy substrate for corrosion protection using self-assembly technique. The prepared DDPO4 Film properties were characterized by X-ray photoelectron spectroscopy (XPS), water contact angle measurement, and electrochemical measurement. Experimental results indicated that DDPO4 was successfully assembled on aluminum alloy substrate via covalent bond attachment. The modified surface was hydrophobic due to the DDPO4 attached to the oxide surface and a hydrocarbon tail-up orientation. Accelerated corrosion test showed that the DDPO4 modified LY12 aluminum alloy substrate exhibited excellent corrosion resistance in an electrolyte containing 0.01 M Cl− + 0.01 M SO42−, and no apparent corrosion pits were observed after an exposure of 96 h. The charge transfer resistance of the DDPO4 covered aluminum alloy was ∼100 times larger than that of the blank aluminum alloy.

Tailored Crosslinking Process and Protective Efficiency of Epoxy Coatings Containing Glycidyl-POSS.

Versatile product protective coatings that deliver faster drying times and shorter minimum overcoat intervals that enable curing at faster line speeds and though lower energy consumption are often desired by coating manufacturers. Product protective coatings, based on silsesquioxane-modified diglycidyl ether of bisphenol-A (DGEBA) epoxy resin, are prepared through a glycidyl ring-opening polymerization using dicyandiamide (DICY) as a curing agent. As silsesquioxane modifier serves the octaglycidyl-polyhedral oligomeric silsesquioxane (GlyPOSS). To decrease the operational temperature of the curing processes, three different accelerators for crosslinking are tested, i.e., N,N-benzyl dimethylamine, 2-methylimidazole, and commercial Curezol 2MZ-A. Differential scanning calorimetry, temperature-dependent FT-IR spectroscopy, and rheology allow differentiation among accelerators’ effectiveness according to their structure. The former only contributed to epoxy ring-opening, while the latter two, besides participate in crosslinking. The surface roughness of the protective coatings on aluminum alloy substrate decreases when the accelerators are applied. The scanning electron microscopy (SEM) confirms that coatings with accelerators are more homogeneous. The protective efficiency is tested with a potentiodynamic polarization technique in 0.5 M NaCl electrolyte. All coatings containing GlyPOSS, either without or with accelerators, reveal superior protective efficiency compared to neat DGEBA/DICY coating.

Laser metal deposition of copper on diverse metals using green laser sources

Green laser sources are advantageous in the processing of copper due to the increase of absorptivity compared with more commonly available infrared lasers. Laser metal deposition of copper with a green laser onto various substrate metals namely copper, aluminium, steel and titanium alloy was carried out and observed through high-speed imaging. The effects of process parameters such as laser power, cladding speed and powder feed rate, and material attributes such as absorptivity, surface conditions and thermal conductivity are tied together to explain the size and geometry of the melt pool as well as the fraction of the power used for melting material. The copper substrate has the smallest melt pool with a high angle, followed by aluminium, steel and titanium alloy. The incorporation times for powder grains in the melt pools vary based on the substrate materials. Its dependency on material properties, including surface tension forces, melting temperatures and material density, is discussed. Oxide skins present on melt pools can affect powder incorporation, most significantly on the aluminium substrate. The lower limits of the fraction of power irradiated on the surface used purely for melting were calculated to be 0.73%, 2.94%, 5.95% and 9.78% for the copper, aluminium, steel and titanium alloy substrates, respectively, showing a strong dependence on thermal conductivity of the substrate material. For a copper wall built, the fraction was 2.66%, much higher than a single clad on a copper substrate, due to reduced workpiece heating. The results of this paper can be transferred to other metals with low absorptivity such as gold.

Eco-friendly conversion coating for the protection of aluminium alloys in the food/beverage canning industries

In view of environmental and health challenges associated with conversion coatings derived from heavy metal ion compounds, this work reports the development and performance of water extracts of Hibiscus sabdariffa (HS) calyces (Hibiscus flower), as a starting green inhibitor in the development of environment friendly, non-carcinogenic conversion coating on aluminium alloy for application in the canning and food packaging industries. Gravimetric analyses revealed that the coating developed sluggishly, a coating weight of about 3 mg was attained after 30 mins of treatment in the coating bath. Fourier transform infrared spectroscopy (FTIR) analyses showed that the coating solution and the coating materials stripped from the aluminium alloy substrate had identical functional groups which were either shifted down or upfield in the FTIR spectra of the coating. However, scanning electron microscopy (SEM) examination revealed that the thin coating developed on aluminium mapped the grain and sub grain boundaries of the substrate. Whereas, within the detection limits of the EDS, the coating is composed essentially of carbonaceous compounds of aluminium and its oxides as well as those of the other elements present in the substrate and in the coating solution. These compounds are probably hydrated. The corrosion performance and adhesion characteristics of the HS coating were better than for the ‘bare’ aluminium alloy substrate.

Specialties of deformation and damage of the topocomposite on a ductile substrate during instrumental indentation

We studied the nature of deformation and damage of topocomposites with instrumental indentation. The topocomposite is considered as a layered system consisting of a solid thin coating coherently bonded to a substrate of a ductile solid material. The object of the study is a topocomposite that consists a coating of titanium nitride deposited by magnetron sputtering in vacuum on a substrate of aluminum alloy. Comparing the balance of energy spent at all stages of indentation using model and experimental diagrams of indentation, the contribution of work dissipated on the deformation to the layered system, on the interfacial delamination at the coating-substrate interface and on the formation of through circular cracks in the coating is estimated. The research results can be used for a qualitative estimation of the efficiency of functional surfaces of machine parts hardened with coatings and for calculating the characteristics of deformation and damage.

Experimental and numerical study of laser surface alloying of Al<SUB align="right">xCu<SUB align="right">0.5FeNiTi high entropy alloy

High entropy alloy possesses superior properties such as high hardness, wear-resistance, thermally stable, high strength to weight ratio, etc. required in industries. The development of high entropy alloy is critical due to the high segregation possibilities of multi-component systems. Processing of high entropy alloy can be done using laser surface alloying. This work reports 3D simulation and, subsequently, an experimental comparison of laser surface alloying process. Such a comparison is crucial to understand the influence of process parameters on bead geometry formation for better process optimisation. This work deals with the processing of AlxCu0.5FeNiTi high entropy alloy over aluminium alloy (AA1050) substrate. The quality parameters (dilution percent, aspect ratio, and bead angle) obtained from experimental and numerical studies are compared. The calculated melt pool depth and width are in a good agreement with the experimental results. An error of 1.72%, 13.95%, and 6.09% in dilution percent, aspect ratio, and bead angle is reported.

ИЗМЕРЕНИЕ И ПРОГНОЗИРОВАНИЕ ТЕМПЕРАТУРЫ ОБРАЗЦОВ МАТЕРИАЛОВ ПРИ ЭКСПОНИРОВАНИИ В РАЗЛИЧНЫХ КЛИМАТИЧЕСКИХ ЗОНАХ

The relation between standard meteorological parameters and surface temperature of samples exposed directly to the sun and in a sheltered environment has been studied using 6–8-year timeframe. The following materials have been used: KMKU-3.150.U0.1 carbon fiber reinforced polymer, KMKS-4.175.Т10 glass fiber reinforced polymer, and D16-AT aluminum alloy substrate with black and white EP-140 epoxy coating . Outdoor weathering has been conducted at Gelendzhik and Moscow testing sites of the All-Russian Institute of Aviation Materials (VIAM). It has been shown that it′s possible to use a multilinear model to estimate the temperature of the materials′ surfaces during their weathering in different climatic regions. The following parameters for 1–12 months’ timeline have been used to estimate samples’ temperature at different locations: air temperature, total solar radiation, solar declination, and solar hour angle.

Исследование взаимодействия цинковых припоев со сплавами алюминия при нанесении трением

Nowadays, due to the search for more efficient and steady processes of aluminum combination and the products that cannot be manufactured using flux, the issue of application of flux-free soldering methods for aluminum-based alloys is highly relevant. The lack of the description of the processes and mechanisms of flux-free soldering by the technique of friction of the solder on the aluminum surface makes it urgent to study and describe them in detail. To carry out the study, the authors produced zinc-based alloys and prepared solder rods using the hot pressing method. Using the technique of friction of a rod against the surface of the heated aluminum substrate, the authors identified minimum temperatures of the setting of zinc solders of different compositions with aluminum surfaces. The experiment proves that these temperatures correlate with the liquidus temperatures of these alloys and have similar values. The dependence of minimum setting temperatures on the Al and Cu content in the solder was obtained. The authors studied the influence of the state of the base metal surface on the spreading area of the Zn-4%Al zinc solder during friction application. The experiments determined the zones of solder spreading over the surface of the AD31 aluminum alloy substrate, depending on the roughness of the base metal surface. The study identified that minimum setting temperatures of solders have similar values against the liquidus temperatures of these alloys, and the adding of copper to a solder reduces these temperatures, on average, by 20° С per each percent of added copper. The flowing of Zn–4%Al solder over the AD31 aluminum alloy surface reaches the largest values when treating the surface with rough-grain abrasive cloths, and the flowing effect decreases with the decrease in roughness.

Tailored alumina coatings for corrosion inhibition considering the synergism between phosphate ions and benzotriazole

This work looked into the synergism between sodium phosphate (SP) and benzotriazole (BT) on the morphology and the corrosion properties of Al–Mg–Si alloy processed via plasma electrolytic oxidation (PEO). To achieve this goal, the fabrication of the coatings was performed at a current density of 100 mA/cm2 for 180 s using alkaline-silicate electrolytes with SP and BT as additives. The addition of SP and/or BT to the electrolyte would lead to change the diameter of the micropores, where a nearly defect-free coating was obtained in the coating processed from electrolyte with SP and BT. Based on the experimental results, it was confirmed that SP and BT additives have some kind of synergism, which can make the coating more compact and effectively improved the corrosion properties of the aluminum alloy substrate.

Production of Phosphorescent Coatings on 6082 Aluminum Using Sr0.95Eu0.02Dy0.03Al2O4-δ Powder and Plasma Electrolytic Oxidation

In this study, a new approach for producing phosphorescent aluminum coatings was studied. Using the plasma electrolytic oxidation (PEO) process, a porous oxide coating was produced on the Al6082 aluminum alloy substrate. Afterwards, activated strontium aluminate (SrAl2O4: Eu2+, Dy3+) powder was filled into the cavities and pores of the PEO coating, which resulted in a surface that exhibits long-lasting luminescence. The structural and optical properties were studied using XRD, SEM, and photoluminescence measurements. It was found that the treatment time affects the morphology of the coating, which influences the amount of strontium aluminate powder that can be incorporated into the coating and the resulting afterglow intensity.

On the PEO treatment of cold sprayed 7075 aluminum alloy and its effects on mechanical, corrosion and dry sliding wear performances thereof

The plasma electrolytic oxidation (PEO) process was used to deposit an alumina coating on a cold sprayed 7075 aluminum alloy to improve the surface properties. The phase compositions, microstructures, basic mechanical properties, as well as the corrosion and the dry sliding wear resistance of cold sprayed 7075 aluminum alloy before and after PEO treatment, were investigated. The results show that a single-layered dense alumina coating with a thickness of ~15–20 μm and hardness of 1353 HV0.01 is realizable on the cold sprayed 7075 aluminum alloy by PEO treatment aided by an aluminate electrolyte. The corrosion current density and wear rate of the alumina PEO coating were 6.27 × 10−7 A/cm2 and 1.22 × 10−6 mm3/N·m respectively, which were three and two orders of magnitude lower compared to the uncoated rolled 7075 aluminum alloy (T6) substrate, thus highlighting the excellent wear and corrosion resistance of the PEO treated cold sprayed Al alloy surface.

Non-Evaporable Getter Ti-V-Hf-Zr Film Coating on Laser-Treated Aluminum Alloy Substrate for Electron Cloud Mitigation

For improving the vacuum and mitigating the electron clouds in ultra-high vacuum chamber systems of high-energy accelerators, the deposition of Ti-V-Hf-Zr getter film on a laser-treated aluminum alloy substrate was proposed and exploited for the first time in this study. The laser-treated aluminum surface exhibits a low secondary electron yield (SEY), which is even lower than 1 for some selected laser parameters. Non-evaporable getter (NEG) Ti-V-Hf-Zr film coatings were prepared using the direct current (DC) sputtering method. The surface morphology, surface roughness and composition of Ti-V-Hf-Zr getter films were characterized and analyzed. The maximum SEY of unactivated Ti-V-Hf-Zr getter film on laser-treated aluminum alloy substrates ranged from 1.10 to 1.48. The X-ray photoelectron spectroscopy (XPS) spectra demonstrate that the Ti-V-Hf-Zr coated laser-treated aluminum alloy could be partially activated after being heated at 100 and 150 °C, respectively, for 1 h in a vacuum and also used as a pump. The results were demonstrated initially and the potential application should be considered in future particle accelerators.

Stability and corrosion property of oil-infused hydrophobic silica nanoparticle coating

ABSTRACT Hydrophobic SiO2 nanoparticles were sprayed onto the aluminium alloy substrate followed by the infusion of PFPE oil. Surface morphologies were observed by scanning electron microscopy and 3D laser confocal microscopy. The water contact angle and the polarization curve were measured before and after long-term immersion tests. The results showed that higher SiO2/PS proportion with lower content of polystyrene can enhance the water contact angle of the SiO2 nanoparticle coating. The water contact angle of the oil-infused surface is barely affected by corrosive immersion periods and the value keeps at a level of 110°∼120°. The oil-infused surface exhibits stable and superior corrosion resistance with the absence of obvious cathode and anode currents on polarization curves after corrosive immersion for 30d. In contrast, the negative shift of E corr by about 300 mV and the increase of i corr by 3 orders of magnitude occur for the superhydrophobic coating.

Application of a pulsed atmospheric arc plasma jet for low‐density polyethylene coating

AbstractThe development of a method for deposition of low‐density polyethylene (LDPE) on rotating three‐dimensional aluminum alloy substrates is presented. LDPE powder with an average diameter of 50 m is dispersed with nitrogen as a carrier gas. This suspension is injected into a plasma plume generated by a pulsed atmospheric arc plasma jet (PAA‐PJ). The optimized PAA‐PJ operating parameters are a pulse frequency of 63 kHz, a power of 1,500 W, a plasma gas (mixture of nitrogen with 3.3% hydrogen) flow of 54 SLM (standard litre per minute), a carrier gas flow of 9 SLM, and a powder rate of up to 5 g/min. The plasma head is moved at 200 mm/s, and the substrate is rotated at 10 rev/min. The net deposition rate reaches 2.5 g/min. A homogeneous, high‐quality film with 1‐mm thickness is deposited on an approximately 100 cm2 substrate surface.

Measurement of the residual stress in chromium nitride coatings deposited on an aluminum alloy substrate using arc ion plating method

Chromium nitride (CrN) coatings were deposited on Al alloy substrates using the arc ion plating method with different bias voltages and different thicknesses. The residual stresses of these samples were measured via x-ray diffraction using the sin2 ψ method because the CrN crystals in the coatings were nonoriented. The stress gradient across the CrN coating was calculated from the curved 2θ-sin2 ψ diagram. In the case of CrN coatings deposited at low bias voltage, the compressive residual stress that formed at the substrate interface was larger than the stress at the surface of the CrN coating. Conversely, in the case of CrN coatings deposited at high bias voltage, the compressive residual stress on the surface of the CrN coating was larger than the stress on the interface with the substrate. In CrN coatings deposited at high bias voltage, very large compressive residual stress on the CrN coating surface decreased with increasing coating thickness.

Effects of Zn powder on alloying during friction surfacing of Al–Mg alloy

The present study investigated the effect of zinc powder on the microstructure and mechanical properties of Al–Mg alloy friction surfaced on an AA5052 aluminum alloy substrate. The zinc powder was applied to the coating through insertion of the hole in the Al–Mg aluminum alloy consumable rod. The addition of Zn powder greatly increases the thermal stability of the coating and reduces kinetic of grain growth. Considering a linear approximation between the grain size and the heat treatment time, the grain growth rate in the coating containing Zn and Zn free is approximately 0.55 μm/h and 1.46 μm/h, respectively. Based on the XRD results in pre heat treatment condition of sample containing Zn powder, in addition to the iron-rich particles and Mg2Si, the MgZn and Mg7Zn3 particles formed. The longtime solid solution and aging treatment result in the AlMg4Zn11 precipitates in the coted sample. After 8 h heat treatment, the coating hardness reaches 70.14 BHN, which shows an increase of 14% as compared to before heat treatment.

Evaluation of laser cleaning for defouling of marine biofilm contamination on aluminum alloys

The environmental friendliness short-pulsed laser removal of marine biofilm contamination developed on the surfaces of aluminum alloy substrates was innovatively applied. Natural biofilms were formed using a seawater immersion method. The surface state was evaluated by considering the cleaning effectiveness and the harm exerted on the aluminum alloy substrate surfaces. The cleaning quality was analyzed using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FT-IR). The laser-induced damage/change to the substrate surface was evaluated using laser scanning confocal microscopy (LSCM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The results indicate that a nanosecond laser can be successfully used to quickly remove marine biofilm contamination from the surface of an aluminum substrate by instantaneous thermal ablation. No clear thermal damage can be found on the laser-cleaned aluminum surface at a lower laser fluence (1.08 J/cm2). In addition to the cleaning of marine biofilm contamination, a higher laser fluence (4.14 J/cm2) can also contribute to the formation of a hierarchical micro- and nanostructured oxidized layer. It is composed of amorphous-nanocrystalline phases.

Corrosion Characterization of Resistance Spot-Welded Aluminum and Steel Couple

Abstract The corrosion resistance of resistance spot-welded (RSW) Al–steel couples of varying combinations of 6016-T4 aluminum alloys and steel substrates, including with and without adhesive at the faying interface, has been successfully evaluated and compared with corresponding self-pierce riveted (SPR) couples. The corrosion resistance of resistance spot-welded Al–steel couples has performed well in cyclic corrosion testing (GMW 17026), and the results are comparable to or better than that of self-pierce riveted couples. SPR couples are more susceptible to galvanic corrosion than resistance spot-welded couples based upon experimentally measured electrochemical potentials from actual joints. The presence of adhesive acts significantly to reduce galvanic corrosion between aluminum alloy and stleel substrates, and moreover, tensile lap-shear strength significantly increased with structural adhesive for both RSW and SPR joining systems. However, despite the presence of adhesive, the lap-shear strength was reduced by more than 50% after cyclic corrosion testing to strength levels comparable to the lap-shear strength of couples having no adhesive and tested in ambient conditions.