Aluminum Alloy Layers Research Articles

PROPERTIES OF THE COMBINED COATING FOR THE RESTORATION OF WORN CYLINDER LINERS

The service life of the cylinder liner of an internal combustion engine after repair caused by wear of the internal working surface has a shorter service life than a new one. This circumstance necessitates the search for a method of applying a more wear-resistant coating. The possibility of using a combined coating to restore worn cylinder liners by applying a layer of aluminum alloy by cold gas-dynamic spraying followed by micro-arc oxidation of the working surface was investigated. (Research purpose) The research purpose is increasing the life of cylinder liners by applying a combined coating using cold gas-dynamic spraying and micro-arc oxidation of the inner working surface of the cylinders. (Materials and methods) Conducted studies on the adhesive and cohesive strength of the coating and comparative tribological tests to determine the suitability of the coating under study for the repair of cylinder liners. We performed studies according to the standards of OST 90148-74 and GOST 23.224-86, respectively. (Results and discussion) The values of adhesive and cohesive strength were determined for various modes of coating with cold gas-dynamic spraying on a cast-iron base. The optimal loading parameters for accelerated wear resistance tests were identified and the run-in rate, the factor and the wear intensity for the studied and reference coatings were calculated. It was established that the adhesive and cohesive strength is sufficient for the application of this method in practice, the wear resistance of the coated sample exceeds the wear resistance of the reference sample. (Conclusions) The combined coating has sufficient strength indicators and high wear resistance indicators compared to the standard, which makes their use in cylinder liners possible and appropriate, however, further investigation of the coating properties is necessary.

Numerical analysis on the energy absorbing characteristics of aluminum/CFRP hybrid tubes under quasi‐static crushing loading

AbstractIn this study, the axial crushing behavior of aluminum/carbon fiber reinforced plastic (CFRP) hybrid tubes are systematically investigated numerically based on a three‐dimensional (3D) progressive damage model. Experiments concerning hybrid tubes with 1/1 and 2/1 lay‐up configurations are performed first to validate the numerical model. Then, the effects of chamfer at the end, stacking configuration, aluminum‐CFRP bonding state and thickness ratio of individual layers on the energy absorption characteristics of aluminum/CFRP tubes are further numerically analyzed. The simulation results suggest that the 3D progressive damage model can effectively simulate the crushing failure process and reveal the energy dissipation mechanism of aluminum/CFRP hybrid tube under crushing. It is observed that increasing the thickness of the CFRP layer does not promote the energy absorption, but the best energy absorption effect can be obtained by using a 1:1 ratio for the thicknesses of the inner and outer aluminum alloy layers in 2/1 hybrid tube. Finally, the economic performance of 2/1 hybrid tube, 1/1 hybrid tube, and aluminum alloy tube as energy‐absorbing structures is theoretically examined. The balance between mass and cost of the 2/1 hybrid tube is proven to be evidently better than that of the conventional 1/1 hybrid tube.

Joining of aluminum and ceramic substrates by interposing molten aluminum–silicon alloy

AbstractThe effects of interposing a molten aluminum alloy layer between pure aluminum and silicon nitride on the strength of joining and properties of the joined sample were investigated. An aluminum‐based alloy containing 12 wt% silicon with a melting point lower than the 660°C melting point of pure aluminum was joined to pure aluminum and a silicon nitride substrate by using polymethylphenylsiloxane. A specimen with the same joining area (1600 mm2) and no alloy layer was prepared for comparison. In thermal cycling tests of Δ190 K, cooled at –40°C and heated at 150°C, the specimen without the alloy layer failed after 200 cycles, whereas the specimen with the alloy layer failed after 500 cycles. The bending strength of the sample with the alloy was approximately 1.5 times that of the sample without the alloy. These results indicate that the alloy layer facilitated the strong joining of the aluminum and substrate.

Experimental Analysis of Circular Milling for Material Identification in Aerospace Industry

In the airplane design, thousand holes should be manufactured by machining leading this process in the first place for process optimization. Recently, the stack materials used in this application are sheet layers of Titanium alloy, Aluminum alloy and CFRP, which normally are machined under different cutting conditions. There are two main solutions when drilling stacks: using the more conservative ones or changing the parameters for each layer. In orbital drilling the forces are lower, with better quality but with longer machining time, compared to drilling, allowing the measurement and control of the process. Smart machining techniques can be applied for recognising and adapting the cutting parameters in real time, depending on a database for decision-making. In this paper, a technique is proposed to identify the cutting material based on the cutting and feed components of the machining force in a circular milling process. Experiments consist of machining separately Titanium and Aluminium alloy workpieces in a similar range of cutting speed and feed, measuring forces and the position of the cutting tool (X,Y, SP) using the machine-tool data. The results show that it is possible to identify the materials using the calculated tangential and radial force components in the tool referential frame because the values of specific cutting and feed force are significantly different for each material. An specific force map is used as a signature to distinguish the materials in real time machining which can be used for orbital drilling in the next step of the research.

Impact damage to fibre metal laminates under compression loading

The effect of in-plane compression loading on the low energy impact response of fibre metal laminates (FML) is investigated. A GLARE®-like FML consisting of bonded layers of aluminium alloy and glass-epoxy composite was impacted at different incident energy levels (up to ∼20 J) while under different axial compression strain levels (up to 8000 μe). Experimental testing and finite element (FE) analysis reveal that compression preloading increases (up to 50%) the maximum impact force experienced by the FML due to shortening of the impact contact time. The out-of-plane deformation of the FML, the amount of plasticity damage to the aluminium layers, and the shape and size of delamination damage to the glass-epoxy layer are dependent on the compression strain level. The FE model predicted the impact response and impact damage to the FML. The FE model is a validated numerical tool to analyse the low energy impact response of FMLs used in compression load-bearing structures.

The structural phase state and strength properties of the surface layer of AA6111-T4 aluminum alloy irradiated by the high-current electron beam

The effect of pulsed electron beam treatment on the structural phase state and strength properties of the AA6111-T4 aluminum alloy was studied. The irradiation led to the formation of a surface layer with a modified structural phase state. The results showed that an oversaturated aluminum-based solid solution is the main phase of the modified layer. Intermetallic phases which were found in the initial state of the alloy, weren’t detected in the modified layer using X-ray diffraction methods. The surface layer is characterized by the high-speed cellular crystallization structure with dimensions of 0.7 μm. The microhardness of the irradiated layer increased by more than 30%. Surface hardening parameters and mechanisms were clarified by investigation of the microstructural modification and the phase transformation both pre and post irradiation. It was shown that the grain boundary and solid solution hardening mechanisms play the key role in increasing the microhardness of the irradiated layer.

Investigation on graphene addition on the quasi-static and dynamic responses of carbon fibre-reinforced metal laminates

In this paper, graphene nanoplatelets (GnPs) were used with carbon fibre/epoxy composite to enhance the mechanical performance of fibre metal laminates (FMLs). The designed FMLs are composed of thin aluminium alloy layers alternating with carbon-fibre epoxy/GnP composite plies with a chemical treatment performed on the aluminium laminate to promote adhesion strength with the epoxy composite. Two different configurations of FMLs were investigated (i) composite plies with unidirectional carbon fibres (U-FMLs) and (ii) composite plies with plain carbon woven (W-FMLs). Samples were tested under dynamic loading (Charpy impact) and quasi-static loading (three-point flexure). The experimental results showed that FMLs with 0.3 wt% GnPs logged the best impact performance; the impact strength of W-FMLs and U-FMLs are respectively 18.2% and 25.2% higher than FMLs without GnPs. FMLs with 0.5 wt% GnPs recorded the highest enhancement in flexural strength, fracture strain and flexural modulus recording increments 23.1%, 19.3% and 48% for the W-FMLs, and 60.3%, 34.5% and 61.4% for the U-FMLs, respectively. Also, an in-depth microscopic analysis was conducted to understand the reinforcing mechanism of GnPs into FMLs. Moreover, a numerical model of a three-point flexural test was developed to show the ability of numerical tools to predict material behaviour at optimized costs. Johnson–Cook and Hashin damage models were used respectively for aluminium alloy and carbon fibre epoxy/GnP composite to accurately predict their deformation and damage modes.

Impact-under-load damage tolerance of a fibre metal laminate

The effect of in-plane loading on the low energy impact damage tolerance of a fibre metal laminate (FML) is experimentally investigated. The FML consisted of stacked layers of aluminium alloy (AA2024-T3) and S2-glass/epoxy (GFRP) composite. The FML was impacted in the transverse direction at increasing energy levels (up to ∼ 20 J) while preloaded in tension or compression at different levels of elastic strain (up to 8000 με). The amount of impact-induced damage and the post-impact compressive strength of the FML were both dependent on the type and magnitude of the preload. The FML sustained plasticity damage and cracking to the aluminium layers; fibre damage, matrix cracking and delamination cracking within the GFRP layer; and debonding cracking between the metal and composite layers under impact loading. The amount of impact damage to the FML increased with the tension and compression strain levels, with more damage created under the tension preload condition. The post-impact compressive strength of the FML also decreased with increasing preload strain, with the reduction being greater for tension compared to compression. The research provides new insights into the impact damage tolerance of FMLs used as load-bearing structural materials.

Microstructure and properties of layered metal/rubber composites subjected to cyclic and impact loading

The paper is devoted to investigation of microstructure and mechanical properties of five-layered metal/rubber composites. The composites were produced by hot bonding of alternating low carbon steel or/and aluminum alloy and rubber layers. Metal/rubber composites can be used as vibration and sound absorbing material in constructions of high-speed trains. In order to study mechanical properties of five-layered metal/rubber composites, impact cyclic and fatigue tests of the obtained composites with different structure was carried out. The tear test results indicated that adhesion bond strength of steel/rubber joint is higher than one of aluminium/rubber joint for the reason of activating and passivating effect of oxide films at interfaces. The impact test results shown that layered architecture of the composite with steel (60 vol%) and rubber (40 vol%) component provides holding of composite‘s impact strength at the level of monolithic low carbon steel with reducing the weight of steel products on 30%. The increased resistance of metal-rubber composites to fatigue fracture at ambient temperature under 100,000-cyclic bending was established. Grain-subgrain refinement, increase in dislocation density and fragmentation of large inclusions were realized on the outer steel and aluminium layers of composites under cyclic loading. The microstructure transformation led to strengthening of composites.

The features of the structural state and phase composition of the surface layer of aluminum alloy Al-Mg-Cu-Zn-Zr irradiated by the high current electron beam

The structural and phase changes in the surface layer of the 1933 aluminum alloy caused by the irradiation of a high-current relativistic electron beam are studied. The impact of the electron beam leads to the formation of a remelted surface layer with surface relief and microcracks. The structural phase state of this layer is determined by the complex impact of the electron beam and the kinetics of melt crystallization under ultrafast cooling. Via X-ray diffraction studies and the results of energy dispersive X-ray microanalysis it became possible to make a conclusion that submicron sizes of magnesium oxide are present in the remelted layer. MgO inclusions are distributed homogeneously in the remelted layer. The presence of MgO inclusions leads to hardening of the surface layer of the alloy. The nature of formation of MgO during the impact of a pulsed electron beam are discussed

Optimization of multilayer thermal protection system by using phase change material under aerodynamic heating

• MTPSs using PCM for insulation are numerically studied. • The addition of PCM helps MTPS fulfill the thermal requirements. • PCM proportion plays a major role in the mass optimization result. • The contents of the two insulation layers affect the system differently. • The optimized designs in terms of mass and size is related to the type of PCM. A multilayer thermal protection system (MTPS) capable to work constantly during multiple launches is important for the new generation of reusable re-entry vehicles to significantly reduce launch costs and protect instruments from overheating. In this paper, phase change material (PCM) is introduced into the MTPS for the optimization purpose in terms of heat performance and structure design. The transient heat transfer characteristics of the system under aerodynamic heating is numerically analyzed, and 2D models using different insulation materials are compared to optimize the system, with respect to temperature distribution, areal density and overall thickness. The finite volume method with the enthalpy-porosity technique is used to resolve the involved multilayer heat transfer problem and the phase transition process. The thermal radiation between the system and the environment, the heat conduction through multi layers, and the convective phenomenon occurring in the PCM section are all considered. The calculation result confirms that the addition of PCM can successfully decrease the temperature of each part in the system below their maximum temperature limits (the C/SiC, Saffil and aluminum alloy layers lower than 1923.15 K, 1873.5 K and 450 K, simultaneously), accordingly help to find the optimal designs with a lighter mass and a smaller size.

Research on the Performance of Diamond-Like Carbon Coatings on Cutting Aluminum Alloy: Cutting Experiments and First-Principles Calculations

The purpose of this study is to investigate the cutting performance of amorphous carbon (a-C) coatings and hydrogenated amorphous carbon (a-C:H) coatings on machining 2A50 aluminum alloy. First-principles molecular dynamics simulation was applied to investigate the effect of hydrogen on the interaction between coatings and workpiece. The cross-section topography and internal structure of a-C and a-C:H films were characterized by field emission scanning electron microscopy and Raman spectroscopy. The surface roughness of the deposited films and processed workpiece were measured using a white light interferometer. The results show that the a-C-coated tool had the highest service life of 121 m and the best workpiece surface quality (Sq parameter of 0.23 μm) while the workpiece surface roughness Sq parameter was 0.35 and 0.52 μm when machined by the a-C:H-coated and the uncoated tool, respectively. Meanwhile, the build-up edge was observed on the a-C:H-coated tool and a layer of aluminum alloy was observed to have adhered to the surface of the uncoated tool at its stable stage. An interface model that examined the interactions between H-terminated diamond (111)/Al(111) surfaces revealed that H atoms would move laterally with the action of cutting heat (549 K) and increase the interaction between a-C:H and Al surfaces; therefore, Al was prone to adhere to the a-C:H-coated tool surface. The a-C coating shows better performance on cutting aluminum alloy than the a-C:H coating.

Effects of Laser Shock Peening on the Mechanical Behaviors and Microstructure of Friction Stir Processed 2A14 Aluminum Alloy

The influence of laser shock peening (LSP) on the microstructures and mechanical behaviors of the friction stir processed (FSPed) 2A14 aluminum alloy was investigated. Microhardness and tensile measurements, as well as wear test, were taken to analyze the changes in mechanical characteristics. The vibration fatigue experiments were also conducted, while the vibration fatigue life of the specimens with different treatments was compared and the fracture morphologies were observed by scanning electron microscopy. The microstructures before and after LSP were observed with electron backscattered diffraction and transmission electron microscopy. The analysis results evidenced that LSP significantly improved the mechanical properties of the FSPed specimens. Meanwhile, LSP increased the dislocation density and promoted the precipitation of the second phases on the surface layer of the FSPed 2A14 aluminum alloy, while their interactions improved the stability of the dislocation structures, which contributed to the improvement of the mechanical behaviors.

The fracture properties of fiber metal laminates based on a 3D printed glass fiber composite

Fiber Metal Laminates (FML) are structures that contain a sequential arrangement of metal and composite materials, which are of great interest to the aerospace sector due to the superior mechanical performance. The traditional manufacturing process for FML involves considerable investment in manufacturing resources depending on the design complexity of the desired components. To mitigate such limitations, 3D printing enables direct digital manufacturing to create FML with customized configurations. In this work, a preliminary mechanical characterization of additively-manufacturing-enabled FML has been investigated. A series of continuous glass fiber-reinforced composites were printed with a Markforged system and placed between layers of aluminum alloy to manufacture hybrid laminate structures. The laminates were subjected to tensile, interfacial fracture toughness, and both low-velocity and high-velocity impact tests. The results showed that the FMLs appear to have a good degree of adhesion at the metal-composite interface, although a limited intralaminar performance was recorded. It was also observed that the low and high-velocity impact performance of the FMLs was improved by 9–13% relative to that of the constituent elements. The impact performance of the FML appeared to be related to the fiber fracture, out of plane perforation and interfacial delamination within the laminates. The present study can provide an initial research foundation for considering 3D printing in the production of hybrid laminates for static and dynamic applications.

The Mechanical Properties of Fiber Metal Laminates Based on 3D Printed Composites.

The production and mechanical properties of fiber metal laminates (FMLs) based on 3D printed composites have been investigated in this study. FMLs are structures constituting an alternating arrangement of metal and composite materials that are used in the aerospace sector due to their unique mechanical performance. 3D printing technology in FMLs could allow the production of structures with customized configuration and performance. A series of continuous carbon fiber reinforced composites were printed on a Markforged system and placed between layers of aluminum alloy to manufacture a novel breed of FMLs in this study. These laminates were subjected to tensile, low velocity and high velocity impact tests. The results show that the tensile strength of the FMLs falls between the strength of their constituent materials, while the low and high velocity impact performance of the FMLs is superior to those observed for the plain aluminum and the composite material. This mechanism is related to the energy absorption process displayed by the plastic deformation, and interfacial delamination within the laminates. The present work expects to provide an initial research platform for considering 3D printing in the manufacturing process of hybrid laminates.

Dispersion curves and identification of elastic wave modes for fiber metal laminates

The current work is devoted to the problem of the validation of dispersion curves and numerical simulations of fundamental Lamb wave and shear horizontal elastic wave modes for fiber metal laminates (FML). In the present study, two types of FM laminates are considered. In the first case, the studied composite material consists of 7 layers: one layer is made of aluminum alloy AW-6060 while the rest of the layers are made of carbon/epoxy resin. In the second case, the FML is constructed of one layer of aluminum alloy and the rest six layers are made of glass/epoxy. In order to extract the dispersion curves for the fundamental S0, SH0, and A0 modes, as well as higher modes from the range 5 up to 1000 [kHz], the stiffness matrix method, is employed. In the first case the computations are performed for the following cross-ply stacking sequences: [Al, ±5°6], [Al, ±15°6], [Al, ±25°6], … , [Al, ±85°6]. Next, the FEM simulations of elastic wave propagation are performed in the case of plates, which are made of analyzed FML composites. In the first studied FML material, the fundamental symmetric mode S0 is generated while in the second case the fundamental antisymmetric mode A0 is excited. It occurred that in the case of aluminum alloy/carbon fibers the generation of the pure fundamental symmetric mode S0 is very difficult. In addition, the fundamental symmetric mode S0, the shear horizontal SH0, and the antisymmetric A0 wave modes are also present. In the case of aluminum alloy and carbon/epoxy, the pure antisymmetric mode A0 can be relatively easily generated. However, a significant dispersion phenomenon is visible. For the aluminum alloy and glass/epoxy, the obtained results are experimentally verified.

Modeling and analysis of thin-walled Al/steel explosion welded transition joints for shipbuilding applications

The study presents an analysis of S355J2+N steel and AA5083 aluminum alloy welded structural joints using explosion welded transition joints of reduced thickness. The transition joint thickness reduction significantly hinders the welding of the joints due to the risk of damage to the Al/steel interface as a result of the high temperatures during welding. Numerical modeling of the welding process is performed to determine safe welding parameters for the transition joint. The numerical analysis is supported by measurements of the temperature areas by a thermographic method. Welded structural joints are analyzed to determine the welding influence on the mechanical properties and microstructure of the transition joints. On this basis, a number of tests are carried out, including microhardness distribution measurements, strength tests of joints in two welding configurations and strength tests of the microspecimens of transition joints. Moreover, an experimental and numerical analysis of strain and stress distributions is carried out in combination with the use of the finite element method and digital image correlation, which allow us to identify the critical areas of the joints with regards to their strength. The results of the microstructural and strength tests carried out using macro- and microspecimens show softening of the aluminum alloy layers. However, the AA5083 and AA1050 layer softening as a result of welding did not reduce the load capacity of the transition joints, which could determine the strength of the dissimilar Al/steel welded structural joints.

Study of high-speed-impact-induced conoidal fracture of Ti alloy layer in composite armor plate composed of Ti- and Al-alloy layers

In order to understand the mechanism of conoidal fracture damage caused by a high-speed fragment-simulating projectile in titanium alloy layer of a composite armor plate composed of titanium- and aluminum-alloy layers, the ballistic interaction process was successfully simulated based on the Tuler–Butcher and GISSMO coupling failure model. The simulated conoidal fracture morphology was in good agreement with the three-dimensional industrial-computed-tomography image. Further, three main damage zones (zones I, II, and III) were identified besides the crater area, which are located respectively near the crater area, at the back of the target plate, and directly below the crater area. Under the high-speed-impact conditions, in zone II, cracks began to form at the end of the period of crack formation in zone I, but crack formation in zone III started before the end of crack formation in zone II. Further, the damage mechanism differed for different stress states. The microcracks in zone I were formed both by void connection and shear deformation. In the formation of zone I, the stress triaxiality ranged from −2.0 to −1.0, and the shear failure mechanism played a dominant role. The microcracks in zone II showed the combined features of shear deformation and void connection, and during the formation process, the stress triaxiality was between 0 and 0.5 with a mixed failure mode. Further, the microcracks in zone III showed obvious characteristics of void connection caused by local melting. During the zone III formation, the triaxiality was 1.0–1.9, and the ductile fracture mechanism was dominant, which also reflects the phenomenon of spallation.

Laser-interference pulse number dependence of surface chemistry and sub-surface microstructure of AA2024-T3 alloy

The laser-based treatment of a metal surface is an intrinsically non-chemical technique that can alter both the topology and chemistry of surfaces. A laser-based treatment for coating and joining applications can offer alternative surface preparations to the chemically-based surface preparation techniques, which are subject to severe environmental protection and hazardous-waste management considerations. In this study, the surface chemistry and sub-surface microstructural changes are investigated for a novel surface processing method using laser interferometry produced by two beams of a pulsed Nd:YAG laser. The two-beam laser-interference allowed the structuring of the surface at length scales much less than that of the laser beam spot. Surface chemistry changes in the oxide layer of AA 2024-T3 aluminum alloy rolled sheet due to laser processing were investigated using x-ray photoelectron spectroscopy (XPS). Near surface microstructural changes have been investigated with scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS), and scanning transmission electron microscopy (STEM) as a function of number of interfering laser shots. SEM microstructure pictures of the top surface shows the minimization of surface defects, as all of the sharp features from a rolled sheet surface were smoothed by laser-structuring. STEM images indicate that the laser-interference processing reduced the formation of CuMn-rich precipitates over a 500–800 nm depth from the top surface. XPS data indicated that the Al oxide layer is modified compared to that of the baseline specimen and that the oxide thickness increases with the number of shots per spot. The additional thicker oxide on Al alloys is expected to increase the corrosion resistance of the coated Al 2024.

Interlaminar Shear Strength and Failure Analysis of Aluminium-Carbon Laminates with a Glass Fiber Interlayer after Moisture Absorption.

This article presents selected aspects of an interlaminar shear strength and failure analysis of hybrid fiber metal laminates (FMLs) consisting of alternating layers of a 2024-T3 aluminium alloy and carbon fiber reinforced polymer. Particular attention is paid to the properties of the hybrid FMLs with an additional interlayer of glass composite at the metal-composite interface. The influence of hygrothermal conditioning, the interlaminar shear strength (short beam shear test), and the failure mode were investigated and discussed. It was found that fiber metal laminates can be classified as a material with significantly less adsorption than in the case of conventional composites. Introducing an additional layer of glass composite at the metal-composite interface and hygrothermal conditioning influence the decrease in the interlaminar shear strength. The major forms of damage to the laminates are delaminations in the layer of the carbon composite, at the metal-composite interface, and delaminations between the layers of glass and carbon composites.