Aluminum Alloy Substrate Research Articles

Irradiation-enhanced Interactions at UO2/Al2O3/Al Interfaces

Combustion synthesis is used to prepare thin UO2 films on aluminum alloy substrates. This simple preparation method involves electrospraying uranyl nitrate + acetylacetone + 2-methoxyethanol solution on the substrate, followed by a short annealing at 350 or 550 °C. The irradiation of films with a 40Ar2+ ion beam (energy of 1.7 MeV and fluences of 7.7 × 1016 and 1.3 × 1017 ions/cm2) is conducted to investigate irradiation-induced restructuring processes. High-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) investigations show that the annealing temperature significantly influences the crystallinity and stability of materials during irradiation. A small amount of Mg in the alloy substrate diffuses into the amorphous Al2O3 interfacial layer between the film and the substrate. Local thermal spikes from the incoming ions facilitate the irradiation-induced mixing of immiscible Al2O3 and UO2 for the materials prepared at 350 °C. This mass diffusion produces relatively large cavities at the interface. Selective diffusion of a more significant amount of Mg for the materials prepared at 550 °C suppresses the mixing of the Al2O3 interlayer with the film but forms MgyU1–yO2±x solid solutions during irradiation. Local thermal heating triggers the precipitation of a discontinuous crystalline MgO layer close to the film surface. The enhanced and selective diffusion of Mg into the film makes the materials prepared at 550 °C more robust and mechanically stable than those prepared at 350 °C.

High entropy alloy thin films on SS304 substrates: Evolution of microstructure and interface modulated by energetic condensation in nanoscale

High entropy alloys (HEAs), as a novel material in the 21st century, possess several advantages, such as excellent corrosion & oxidation resistance and high mechanical properties. HEA thin films show these favourable properties with lower material costs than their bulk counterparts. Studying the HEA film-substrate interface represents challenges but is of extreme importance for the understanding of growth mechanisms with important implications for film adhesion. However, most HEA films were deposited on monocrystalline silicon substrates with limited practical applicability. Further, where commercial stainless steel, aluminium or titanium alloy substrates were used, the microstructure and chemistry at the interface were neglected. Here, we deposited AlCrFeCoNiCu0.5 HEA thin films on stainless steel 304 (SS304) substrates using cathodic arc deposition with different substrate biases. The crystallography and microstructure were investigated using an X-ray and electron-microscopy based chatacterization. A transition of an incoherent to semi-coherent interface was observed from 0 V to -50 V of the substrate bias. Energy dispersive spectroscopy demonstrated a transition of Cr2O3 to aluminum oxide across the interface. The nanoindentation tests revealed the significant improvement of mechanical properties of SS304 with HEA coatings. High-strength HEA (8.0 ± 0.2 GPa) thin films with semi-coherent interfaces were manufactured on SS304.

Fretting wear behavior of aluminum coatings

The aluminum bronze coating is a type of soft solid lubricant film with excellent performance. In this work, to improve the wear resistance and tribological behavior of the aluminum alloy, the aluminum bronze coatings were prepared on aluminum alloy substrates using the High- Velocity Oxygen Fuel (HVOF) system. Fretting wear tests were performed on the coatings at 200 °C with different frequencies to analyze the wear behavior. The worn surface was characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that as the frequency increased from 5 Hz to 15 Hz, the coefficient of friction increased from 0.653 to 0.929. It then decreased to 0.890 at 20 Hz. There was an overall trend of the coefficient of friction increasing and then decreasing. The worn surface’s morphology changed from pits to bulges. At a low frequency, the wear mechanism was abrasive wear with delamination. As the frequency increased, adhesive wear was observed and gradually became the dominant wear form. Oxidation occurred on the surface of the worn tracks caused by the high temperature and thermal effect of high-frequency micromotion. Due to the intensification of the oxidation phenomenon, oxidation films formed on the worn surface. The wear rate of the coating was significantly reduced. The oxide was identified as mainly CuO and Cu2O. The presented results confirmed that the aluminum bronze coating fabricated via HVOF exhibited a great resistance performance even at a high frequency.

Tribological properties of PEEK-based composite coating prepared by thermal spraying

To improve the friction wear performance of the aluminum alloy scroll disc of the scroll compressor under dry friction conditions, the C-MoS2-PTFE-PEEK coating was prepared on the surface of the 4032 aluminum alloy substrate by thermal spraying. The friction and wear performance of C-MoS2-PTFE-PEEK coating under dry friction conditions was investigated via friction wear test, hardness test, coating adhesion scratch test, x-ray diffraction analysis test, morphological characteristics, element distribution test, And XPS photoelectron spectrometer. Moreover, the frictional wear performance of the C-MoS2-PTFE-PEEK coating was compared with that of the anodic oxide film of 4032 aluminum alloy and the Ni-plated coating of 4032 aluminum alloy. The results show that the hardness of C-MoS2-PTFE-PEEK coating is 102.8 HV0.2. The C-MoS2-PTFE-PEEK coating has good lubrication properties under dry friction conditions due to the synergistic effect of MoS2 and PTFE, which can effectively resist deformation and reduce the coefficient of friction. The average friction coefficient under 5N, 10N, and 15N loads are 0.12, 0.15, and 0.23, respectively. The Graphite can effectively form a solid lubricating film, improve the adhesion resistance of the composite, and cause the shallow and small wear mark of C-MoS2-PTFE-PEEK coating; The wear rate and friction coefficient of C-MoS2-PTFE-PEEK coating under different loads are lower than that of the anodic oxidation film of 4032 aluminum alloy and the Ni-plated coating of 4032 aluminum alloy, showing excellent anti-friction and wear resistance. The wear mechanism of C-MoS2-PTFE-PEEK coating under different loads is mainly fatigue wear, adhesive wear, and abrasive wear.

Investigation of the morphologies of chelate flame-sprayed metal oxide splats

This paper reports an investigation of Er2O3 splats formed by metal–ethylenediaminetetraacetic acid (EDTA) complex particles that were applied onto aluminum alloy substrates by flame spraying. The splat morphologies and coating microstructures were analyzed under different conditions. The effects of the in-flight particle temperature of the carrier gases and the impact particle deposition temperature on solidification of the molten droplets were evaluated with a rotating dodecahedron stage operated at velocities of 30, 75, and 90 rpm and with different temperatures and angles of incidence. Various techniques were used to analyze the surfaces and cross sections of the splats and coatings formed under the different conditions. Most of the splats underwent transitions from disk shapes (ratio > 85 %) to irregular shapes (circularity of 0.61–0.80) with increasing rotational velocity. The spray process provided a coating with a porosity of 23.3 % at a powder flow rate of 20 g/min. The temperature reached during the chelate flame spraying (CFS) process and the condensing velocity of the deposited splat, rather than the in-flight particle temperature, were found to control the splat morphology. This synergistic condensation effect paves the way to successful deposition of high-temperature structural ceramic coatings such as Er2O3 with the CFS method.

Structure–Property Relationships in Epoxyurethane Polymers Based on Erythritol Dicarbonate

AbstractThe highly reactive erythritol dicarbonate (EDC) allows facile design and preparation of solvent‐ and catalyst‐free epoxyurethane polymers. Diglycidyl ether of bisphenol‐A (DGEBA) and oligo polyhydroxyurethanes are used to produce epoxyurethane polymers (o‐PHUs). The o‐PHUs are prepared using cyclic carbonates derived from erythritol and various diamines (aliphatic amine and polyether amine) or polyamines (diethylene triamine (DETA) and triethylne tetramine (TETA)). Active secondary amino groups derived from o‐PHUs polyamines form hydrogen bonds between urethane carbonyls in epoxy hybrid networks with the highest cross‐linking density (1293 mol m−3), glass transition temperature Tg (93 °C), and ultimate tensile strength (34 MPa). And the ether bond provides a significant potential for hydrogen bonding between hydroxyl group and ether oxygen, forming strong hydrogen bond cross‐linking between molecular chains, with cross‐linking density and ultimate tensile strength comparable to polyepoxyurethane derived from polyamines, except for a lower Tg (27 °C). In addition, these polyepoxyurethanes have superior adhesion to wood, aluminum alloy, and polymethyl methacrylate (PMMA) substrates. This versatile oligo PHUs would provide a wide range of fabrication options for adhesive epoxyurethane polymers.

Preparation of superhydrophobic composite coating on 2024 aluminum alloy and its stability and corrosion resistance

2024 aluminum alloy is treated by anodic oxidation process. After that, the anodized aluminum is coated with ZnO particles sol to form a sol coating. Taking advantage of the porous characteristics of the anodized aluminum, the sol coating and the anodized aluminum are closely combined to construct a superhydrophobic composite coating after heating treatment. The experimental results show that the superhydrophobic composite coating has protrusions of various shapes and holes interlacedly distributed to form a micro-nano hierarchical structure, and its morphology is obviously different from that of the anodized aluminum. The superhydrophobic composite coating is composed of Al, O, S, Zn, Si and C elements. Meanwhile, Zn, Si and C elements are derived from the sol coating. The contact angle of the superhydrophobic composite coating reaches 151.2°, which has good resistance to wear and impact damage. The superhydrophobic composite coating has the lowest corrosion current density of 3.79 × 10−6 A/cm2, which is more than an order of magnitude lower than that of 2024 aluminum alloy substrate, showing good corrosion resistance. The superhydrophobic composite coating relies on the micro-nano hierarchical structure with low surface energy which can effectively block the intrusion of corrosive media and increase corrosion resistance to provide an ideal protection for 2024 aluminum alloy substrate.

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.

Influence of Surface Roughness of Aluminum Alloy Substrate on Tensile Adhesive Strength of Plasma-Sprayed Yttria-Stabilized Zirconia Coatings

The adhesive mechanism of thermal sprayed ceramic coating is not clear because of the complicated profile of the blasted surface and the microstructure of the coating. In particular, little research has been carried out on the adhesive mechanism on light metal substrates. The objective of this study was to investigate the effect of surface roughness on the adhesive strength of yttria-stabilized zirconia coatings applied by atmospheric plasma spraying on an aluminum alloy (JIS A5052) substrate. Tensile adhesive and interfacial indentation tests were performed to evaluate their bonding properties. The substrates were blasted at three different pressures and seven different blast angles using fused alumina abrasives of three different particle sizes. Our measurements revealed that the tensile adhesive strength decreased with increasing substrate roughness (root mean square slope, RΔq). After the tensile strength tests, the fracture surfaces were observed using an FE-EPMA analyzer and analyzed using an X-ray fluorescence analyzer. It was found from elemental analysis that the fractured part shifted to the substrate with increasing RΔq. It was concluded that the tensile adhesive strength decreased with increasing surface roughness owing to the low strength of the substrate.

Antibacterial anodic aluminium oxide-copper coatings on aluminium alloys: preparation and long-term antibacterial performance

Anodic aluminium oxide-copper (AAO-Cu) coatings were prepared on the aluminium (Al) alloy substrates to attain excellent antibacterial performance and mechanical stability. The nanoporous AAO interlayer was obtained by anodic oxidation with an outer Cu layer deposited by electroplating. The intermediate zone (∼2 μm thick) of the AAO-Cu coating plays a significant role in the coating properties. The interlocking effect in the AAO-Cu intermediate zone significantly enhances the coating adhesion and curbs the coating defoliation. The antibacterial tests show that the AAO-Cu zone provides excellent antibacterial ability even when the outer Cu coating was removed. The sustained antibacterial rate of the AAO-Cu intermediate zone against E. coli exceeded 95%. The Cu ions released from the embedded Cu in the nanoporous AAO structure ensure a long-term antibacterial capability. This coating system can be promoted in a large wide range of antibacterial products in public.

Effects of frequency on the fretting wear behavior of aluminum bronze coatings

The aluminum bronze coating is a type of soft solid lubricant film with excellent performance. In this work, to improve the wear resistance and tribological behavior of the aluminum alloy, the aluminum bronze coatings were prepared on aluminum alloy substrates using the High-Velocity Oxygen Fuel (HVOF) system. Fretting wear tests were performed on the coatings at 200 °C with different frequencies to analyze the wear behavior. The worn surface was characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that as the frequency increased from 5 Hz to 15 Hz, the coefficient of friction increased from 0.653 to 0.929. It then decreased to 0.890 at 20 Hz. There was an overall trend of the coefficient of friction increasing and then decreasing. The worn surface's morphology changed from pits to bulges. At a low frequency, the wear mechanism was abrasive wear with delamination. As the frequency increased, adhesive wear was observed and gradually became the dominant wear form. Oxidation occurred on the surface of the worn tracks caused by the high temperature and thermal effect of high-frequency micromotion. Due to the intensification of the oxidation phenomenon, oxidation films formed on the worn surface. The wear rate of the coating was significantly reduced. The oxide was identified as mainly CuO and Cu2O. The presented results confirmed that the aluminum bronze coating fabricated via HVOF exhibited a great resistance performance even at a high frequency.

Multi-Perspective Evaluations of Laser-Removal Quality of Acrylic Polyurethane Coatings on Aluminum Alloy Substrate

Evaluation systems for objects after laser removal have not been systematically established, yet they have great significance for repairing engineering coating materials. In general, this paper mainly focused on the surface quality after laser removal, which was simulated by thermal models and characterized by microscopic, residual chemical compositions, and wettability. The laser removal threshold was considered to be a key indicator to regulate removal precision. Here, the thermal model was used to explore the threshold was 15 J/cm2, and the ablation P was 308 W at 100 kHz. Besides, the surface structure was observed through simulation before experiments. It also predicted the effect of laser power and overlapping on surface roughness, and therefore provided the theoretical reference for experiments. Then, two groups of samples were set up of the surface of acrylic polyurethane coatings on 2024 aluminum alloy with and without anodizing treatment, respectively. After the coatings were removed, microscopic morphologies demonstrated a wavy undulation structure with little residue. Meanwhile, the increments of roughness were less than 0.5 μm and the surfaces were with nice wettability. Evaluating the surface quality from the above aspects is meaningful and helpful for the non-destructive cleaning of aircraft skin coatings.

Joining Stainless-Steel AISI 304 and High-Strength Aluminum Alloy AA 6082 by Brazing Using Al-Ge-Si Foils

An Al-40.0Ge-3.4Si wt.% alloy foil with a thickness of 50 ± 5 μm, obtained via an ultrafast solidification method, is described in this work. A complete wetting of the aluminum alloy substrate with a wetting angle of 0° is observed, and the formation of a drop with a wetting angle of 30 ± 5° is observed on the steel substrate. Similar and dissimilar brazed joints of aluminum alloy AA 6082 and stainless-steel AISI 304 are obtained. The microstructure of the AA 6082/AA 6082 brazed seam is homogeneous and contains particles of an Al7Fe2Si system intermetallic compound and particles of an Al-Ge eutectic composition. The brazed seam of the AISI 304/AISI 304 joint is formed due to the formation of the Al8Fe2(Si, Cr) intermetallic compound reaction layer on the steel surface. The proposed scheme for the AISI 304/AA 6082 brazed joint formation is given. The brazed seam represents the Al8Fe2(Si, Cr) reaction layer on the steel surface, the thickness of which depends on the holding time during brazing, and the aluminum matrix of which has particles of a composition close to an Al-Ge eutectic. The obtained results could be used for the optimization of time–temperature brazing modes in order to improve the mechanical characteristics of AISI 304/AA 6082 dissimilar joints.

Creep Crack Growth Behavior during Hot Water Immersion of an Epoxy Adhesive Using a Spring-Loaded Double Cantilever Beam Test Method.

Double cantilever beam (DCB) tests were conducted by immersing the specimens in temperature-controlled water while applying a creep load using a spring. By introducing a data reduction scheme to the spring-loaded DCB test method, it was confirmed that only a single parameter measurement was sufficient to calculate the energy release rate (ERR). Aluminum alloy substrates bonded with an epoxy adhesive were used, and DCB tests were performed by changing the initial load values, spring constants, and immersion temperatures for two types of surface treatment. The initial applied load and spring constant had no effect on the ERR threshold. In contrast, the threshold decreased with the increasing immersion temperature, but even in the worst case, it was 15% of the critical ERR in the static tests. Using the creep crack growth relationship, it was revealed that there were three phases of creep immersion crack growth in the adhesive joints, and each phase was affected by the temperature. The spring-loaded DCB test method has great potential for investigating the combined effects of creep, moisture, and temperature, and this study has demonstrated the validity of the test method. The long-term durability of adhesive joints becomes increasingly important, and this test method is expected to become widespread.

Microstructure, mechanical property and corrosion resistance of FeCoCrNi-M high-entropy alloy coatings on 6061 aluminum alloy prepared by laser cladding

To improve the comprehensive surface performance of 6061 aluminum alloys and reduce the influence of Al dilution behavior on the coating quality, FeCoCrNi-M (M = Mn, Cu, Ti, −) high-entropy alloy coatings were prepared by a double-layer laser cladding method. The FeCoCrNi, FeCoCrNiMn and FeCoCrNiCu coatings all consisted of a single face-centered cubic (FCC) phase. The FeCoCrNiTi coating consisted of FCC, body-centered cubic (BCC), Laves and AB-type phases. The addition of Mn or Cu decreased the hardness of the FeCoCrNi coating from 209 HV to 188 or 165 HV, and increased the wear rate from 1.16 × 10−4 mm3/N·m to 1.62 × 10−4 or 3.01 × 10−4 mm3/N·m. The addition of Ti increased the hardness to 908 HV and decreased the wear rate to 2.32 × 10−5 mm3/N·m. The current density of the FeCoCrNi coating (6.37 × 10−8 A/cm2) in 3.5 wt% NaCl solution increased with Cu or Mn addition (2.15 × 10−7 or 3.26 × 10−7 A/cm2), but decreased with Ti addition (1.15 × 10−8 A/cm2). FeCoCrNi-M coatings significantly enhanced the hardness, corrosion resistance and wear resistance of the aluminum alloy substrate.

Properties of Cold Sprayed Titanium and Titanium Alloy Coatings after Laser Surface Treatment.

Additive manufacturing (AM) has seen remarkable development in recent years due to relatively high efficiency of the process. Cold spraying (CS) is a particular method of AM, in which titanium and titanium alloy powders are used. CS is a very competitive technology enabling the deposition of coatings, repairing machine parts, and manufacturing new components. For specific applications, the surface of cold-sprayed materials may require further processing. This paper reports an attempt to employ laser surface treatment (LST) of cold-sprayed coatings on an aluminium alloy substrate. The influence of laser beam interaction time on the coatings' properties was analysed. The microstructure was investigated and observed employing scanning electron microscopy (SEM). To evaluate residual stress after CS and LST, the sin2ψ technique was used. Investigations were also performed on Vickers hardness, contact angle, and surface roughness. Significant changes in the surface morphology of the coatings and elevated residual stress levels dependent on the laser beam interaction time were observed. Increased Vickers hardness was recorded for titanium alloy Ti6Al4V. LST also led to increased surface hydrophilicity of the modified materials Ti and Ti6Al4V.

Stable cladding of high reflectivity pure copper on the aluminum alloy substrate by an infrared-blue hybrid laser

• A coaxial infrared-blue hybrid laser was adopted in cladding pure copper on the AlSi7M-g alloy substrate, which can make up for the forming instability of infrared laser and blue laser. • Hybrid laser can bring about a larger molten pool size, a slower cooling rate and a coarser microstructure. • The improvement in cladding stability under hybrid laser is closely related to the great increase in total laser absorption rate of the high reflectivity alloy and the reduction in fluctuation of absorption rate. A coaxial infrared-blue hybrid laser system was adopted in the cladding of high reflectivity pure copper on an AlSi7Mg alloy substrate, and the cladding stability, molten pool size and microstructure of the cladded samples by three types of laser sources (infrared, blue and their hybrid sources) were compared. The infrared-blue hybrid laser was validated to compensate for the forming instability of a high-power infrared laser and a low-power density blue laser. In addition, the heat accumulation in the cladding process with the hybrid laser was more obvious and the cooling rate was slower (1.36 × 10 4 K/s), which led to a coarser microstructure (1.56∼2.42 μm). Therefore, the hybrid laser can bring about stability and a larger molten pool size in cladding pure copper on the aluminum substrate, which is closely related to the great increase in the total laser absorption rate of the high reflectivity alloy and the reduction in the fluctuation of the absorption rate.

Effect of Cu2+ on the corrosion behavior and mechanism of Al-2 %Zn coatings in 3.5 % NaCl solution

• Effect of the reduction of Cu 2+ on the corrosion behavior and mechanism of Al-2%Zn coating in NaCl solutions was reported. • Impact of reduction reaction of more Cu 2+ is more pronounced, resulting in a negative shift in corrosion potential and a decrease in cathodic Tafel slope. • General corrosion morphology changes to localized as the concentration of Cu 2+ increases to 110 μg/L. • The corrosion products film plays a shielding effect when the concentration of Cu 2+ is below 50 μg/L. A layer of Al-2%Zn coating was sprayed on 5083 aluminum alloy substrate. The effect of Cu 2+ on the corrosion behavior and mechanism of the coating in 3.5 wt.% NaCl solution was investigated using electrochemical techniques and surface analysis. The experimental results show that when the concentration of Cu 2+ is lower than 50 μg/L, an inductive semicircle appears in the electrochemical impedance spectrum at the beginning of immersion. When Cu 2+ concentration is 110 μg/L, no inductive semicircle was detected, indicating that the degradation process was promoted in the presence of Cl - . XPS and EDS analysis shows that Cu are formed in the corrosion process. With the increase of Cu 2+ concentration, the reduction of Cu 2+ to Cu gradually plays an important role in the cathodic reaction, while the reduction of oxygen is relatively weak, leading to the reduction of the cathodic slope and the negative shift of the mixed potential. The corrosion products film on the surface will cover the corrosion pits and plays a shielding effect due to the active dissolution of the coating. When the concentration of Cu 2+ exceeds 50 μg/L, this effect disappears and the surface morphology changes to obvious local corrosion morphology, including flaking and cracking.

Study on the Influence of Graphene Content Variation on the Microstructure Evolution and Properties of Laser Additive Manufacturing Nickel-Based/SiC Composite Cladding Layer on Aluminum Alloy Surface.

A Ni25-10% SiC-X% graphene (mass fraction X = 0, 0.5, 1.0, 1.5) composite cladding layer was prepared on a 6063 aluminum alloy substrate using laser cladding in order to enhance the comprehensive performance of the aircraft refueling interface. The effect of the graphene content on the organization and properties of nickel-based silicon carbide composite cladding layers was investigated by laser melting. The macroscopic morphology, microstructure, hardness, elemental changes, corrosion and wear resistance of the cladding layer were studied by optical microscopy, scanning electron microscopy, a hardness tester, an X-ray diffractometer, an electrochemical workstation and an M-2000 frictional wear tester. The results indicated that the nickel-based clad layer without graphene incorporation had the worst forming, with a large number of pores and cracks in the cladding layer. Because graphene agglomerated easily, cracks were regenerated when the content of graphene was higher than 0.5%. The material phases of the cladding layer without graphene incorporation were mainly: Al3Ni2, Fe3Si and SiC. Due to the addition of graphene, the clad layer of specimen 2 was refined and a large number of hard phases, such as CrC and Cr23C6, were generated, which led to the increase in the hardness of the clad layer. When the content of graphene was further increased, the number of hard phases such as CrC and Cr23C6 produced in the cladding was relatively reduced due to the agglomeration of graphene, and the hardness of the cladding was reduced. As the impermeability of graphene reduces the diffusion of corrosive media to the substrate, the generation of hard-phase Al3Ni2 in the cladding layer makes the corrosion resistance of the cladding layer increase with the increase in graphene mass fraction. The result is that, when the content of graphene was 0.5%, the overall performance of the clad layer was the best, where its average hardness was increased by 40%, the average coefficient of friction was reduced by 12.7% and the wear rate was reduced by 60%.

Comparative Mechanical Study of Pressure Sensitive Adhesives over Aluminium Substrates for Industrial Applications.

The use of adhesives for fixing low-weight elements is showing increasing interest in the industry, as it would reduce the weight of the assembly, costs, and production time. Specifically, the application of pressure-sensitive adhesives (PSAs) to join non-structural naval components to aluminium substrates has not yet been reported. In the present work, a study of the mechanical behaviour of different double-sided PSAs applied on bare aluminium alloy substrates is performed. The influence of surface roughness, surface chemical treatments, and the matrix of the adhesives is studied through different mechanical tests, such as shear, T-peel, and creep. The application of an adhesion promoter improved the mechanical behaviour. Low roughness substrates provided better performance than ground samples. Acrylic foam adhesives were subjected to creep tests, whose results were fitted to a simple mathematical model, predicting the fracture time as a function of the applied load.