Al Sheet Research Articles

Aluminum sheet induced flower-like carbon nitride anchored with silver nanowires for highly efficient SERS detection of trace malachite green

The sensitive detection of malachite green (MG) in aquaculture wastewater is necessary for its residual poses a great threat to the living systems. Herein, the flower-like C3N4 (f-C3N4) nanostructure induced by Al sheet in the hydrothermal process is constructed. Subsequently, Ag nanowires (AgNWs) supported on Al/f-C3N4 and the strong interaction between AgNWs and Al/f-C3N4 are confirmed by XPS, Raman spectroscopy, UV–vis diffuse reflectance and fluorescence spectroscopy. Importantly, the portable Al/f-C3N4/AgNWs substrate shows the outstanding SERS response for MG, which is attributed to enhanced electromagnetic effect of AgNWs on large amount of corrugated and creviced regions in the flower-like Al/f-C3N4 and the charge transfer among the components. Also, the prepared Al/f-C3N4 nanostructure provides large specific surface area and abundant “N” active sites for AgNWs, and the high enrichment ability of Al/f-C3N4 towards MG molecules by the strong π-π stacking interaction. The detection limit of Al/f-C3N4/AgNWs for MG is as low as 8.38 × 10−12 mol L−1. The substrate can be reproduced and reused for at least 7 cycles, and the activity can still be kept after laid up for 49 days. Importantly, it unfolds a good sensitivity and selectivity for MG in actual water sample. Results indicate that the Al/f-C3N4/AgNWs substrate has a promising potential in practical application for trace detection of MG.

High-performance and long-cycle life of triboelectric nanogenerator using PVC/MoS2 composite membranes for wind energy scavenging application

Triboelectric nanogenerator (TENG) is a new energy technology, which can effectively convert ambient various mechanical energy into electricity by coupling effect of triboelectrification and electrostatic induction, yielding self-powered microelectronic devices. However, the surface charge density of triboelectric materials and the performance degradation and failure of TENG caused by wear are the key bottlenecks for its practical application. Here, we propose a high-performance and long-life TENG for harvesting wind energy that uses polyvinyl chloride/molybdenum disulfide (PVC/MoS2) composite membranes and polyamide (PA) membranes as matching triboelectric materials, and aluminum (Al) sheets with micro-nano structures as electrodes. Adding a small amount of MoS2 with excellent lubricating properties can not only effectively increase the surface charge density of composite films but also improve its wear resistance, which enhances the output performance and extends the life time of the TENG. The optimized TENG can generate an output voltage, current and maximum power up to 398 V, 40 μA and 1.23 mW, respectively, which can power tens of commercial light-emitting diodes (LEDs) and a water thermometer. Moreover, the friction coefficient of PVC after the doping of 2.5 wt% MoS2 is 0.29, which is 19.4% lower than that of pure PVC film, providing a new way to improve the surface charge density and the durability of triboelectric materials.

Resistance element welding of 7075 aluminum alloy to Ti6Al4V titanium alloy

In this paper, Al/Ti joints are produced by resistance element welding (REW). A hole is made in the Al sheet and a welding element (Ti6Al4V rivet) is inserted into the hole followed by resistance welding to create a metallurgical bond between the Ti rivet and Ti sheet. The mechanical properties, fracture mode, microstructure, and hardness distribution of the joints are analyzed. The REW joints show higher tensile-shear load and energy absorption than present riveted joints. The maximum peak load and energy absorption of the REW joints improved with the increasing of rivet diameter. The failure mode for Al/Ti REW joints transits from interfacial to pullout mode, and then to fully pullout mode with increasing welding current. The nugget microstructure mainly consists of acicular α′ phase martensite. A discontinuous intermetallic compound layer is formed at the Ti/Al interface, and it consists of TiAl2, TiAl, or a mixture thereof.

The Effect of Plume Generated on the Microstructural Behavior of the Weld Mixed Zone in High-Speed Laser Dissimilar Welding

Dissimilar laser welding has been researched to combine the excellent anticorrosion and high strength properties of Ti and the low weight and cost of Al. However, when welding dissimilar Al and Ti sheets, many kinds of intermetallic compound are easily generated. Therefore, intermetallic compounds and differences in material properties make joining such dissimilar metals very difficult. Previous studies clarified that ultra-high welding speed could suppress the weld defects. To elucidate the mechanism of Al and Ti dissimilar laser welding, material behavior of the weld fusion zone and components of fume generated during the ultra-high speed welding process were observed and analyzed using energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high speed cameras, and a spectrometer. The results show that the atom movement of Al and Ti in the weld plume affects the behavior of elemental components distributed in the weld fusion zone.

Technical note: Unresolved aspects of the direct vapor equilibration method for stable isotope analysis (<i>δ</i><sup>18</sup>O, <i>δ</i><sup>2</sup>H) of matrix-bound water: unifying protocols through empirical and mathematical scrutiny

Abstract. The direct vapor equilibration laser spectrometry (DVE-LS) method has been developed for obtaining matrix-bound water stable isotope data in soils, the critical zone, and bedrock, deriving therefrom subsurface water flow and transport processes and, ultimately, characterizing, for example, groundwater recharge and vulnerability. Recently, DVE-LS has been increasingly adopted due to its possible high sample throughput, relative simplicity, and cost-efficiency. However, this has come at the cost of a non-unified standard operation protocol (SOP), and several contradictory suggestions regarding protocol details do exist which have not been resolved to date. Particularly, sample container material and equilibration times have not yet been agreed upon. Beside practical constraints, this often limits DVE-LS applicability to interpreting relative isotope dynamics instead of absolute values. It also prevents data comparability among studies or laboratories, and several previous comparisons of DVE-LS with other, more traditional approaches of water extraction and subsequent stable isotope analysis yielded significant discrepancies for various sample matrices and physical states. In a series of empirical tests, we scrutinized the controversial DVE-LS protocol details. Specifically, we tested 10 different easily available and cost-efficient inflatable bags previously employed or potentially suitable for DVE-LS sample collection and equilibration. In storage tests similar to the DVE-LS equilibration process but lasting several weeks, we quickly found heat-sealed bags made of laminated aluminum (Al) sheets to be superior by several orders of magnitude over more frequently used freezer bags in terms of evaporation safety and accompanying adverse isotope effects. For the first time, Al-laminated bags allow the applied equilibration time to be adapted exclusively to sample requirements instead of accepting reduced data quality in a trade-off with material shortcomings. Based on detailed physical considerations, we further describe how to calculate the minimum available container headspace and sample-contained liquid water volume and how their ratio affects analytical precision and accuracy. We are confident that these guidelines will expand DVE-LS applicability and improve data quality and comparability among studies and laboratories by contributing to a more unified, physically well-founded SOP based on more appropriate components.

Experimental investigations on the influence of ‘chimney-effect’ on fire response of rainscreen façades in high-rise buildings

In recent years, external wall fires (or façade fires) are occurring due to mixed contribution of exterior cladding and continuous insulation in the chimney like construction of rainscreen façades. In the present work, a new experimental setup is developed and demonstrated for the initial screening of façade assembly at a lab-scale. It incorporates the real physics for investigating the fire hazards of flammable polymeric materials and the chimney effect together. Different combinations of exterior cladding (Al-45, Al-45 Class 0, Al-45 Class B) and continuous insulation (Expanded polystyrene, Polyisocyanurate and Mineral wool) with and without chimney are selected for studying their fire behaviour. The pressure differential combining with re-radiation inside the cavity led 3–6 times higher mass burning rate, flame height and temperature in tests with chimney effect to that of without for the same combination of products. With chimney, secondary fire sources are generated due to the dripping of products which further enhanced the burning and spread rate. A critical width of the chimney (13–50 mm) is established at which maximum vertical fire spread was noticed. Furthermore, the visual observations indicated that the products having thin outer Al sheets are prone to 30% early structural failure. Comparison of results with large-scale tests validated the usefulness of the current setup as an intermediate test between small and large scale for studying fire behaviour of façade materials.

The Improved Mechanical Anisotropy of a Commercial Al–Cu–Mg–Mn–Si (2017) Aluminum Alloy by Cross rolling

The optimized thermomechanical process is an effective way to improve and control the properties of metallic alloys. Herein, the influence of unidirectional cold rolling and cross cold rolling on the texture and mechanical properties of a commercial AlCuMgMnSi (2017) alloy is investigated. The Al sheets successfully prepared by the three cold rolling methods have different dominant texture components, and show different texture transformation routes during solution and aging treatments. In addition, the influence of the rolling direction on the texture of the 2017 alloy is discussed. The cross‐rolled sheets subjected to artificial aging show the strongest yield strength of ≈366 MPa and ultimate tensile strength of ≈426 MPa, as well as excellent mechanical anisotropy. Its in‐plane anisotropy (IPA), , and Δr values are 0.7%, 0.576, and 0.042, respectively. The effects of texture and precipitates on the anisotropy of aged 2017 alloys are also discussed separately. This work may help to understand the relationship between rolling direction and the mechanical anisotropy of aluminum alloys and provide a basis for industrial production.

Investigation of residual stresses in planar dissimilar magnetic pulse welds by neutron diffraction

Residual stresses are investigated for the first time in a dissimilar AA1050–DP450 steel magnetic pulse weld using neutron diffraction. Close to the joint interface, tensile residual stresses are observed in the Al sheet and compressive residual stresses are identified in the steel sheet. At the interface, longitudinal tensile stresses are dominant on the aluminum side and transverse and normal stresses show similar behavior. On the steel side, normal stresses remain small, and longitudinal and transverse residual stresses have a similar trend. It was identified that close to this tensile region in aluminum, residual stresses in steel become more compressive. These residual stress distributions essentially result from (i) the respective yield strengths of Al and steel and (ii) the high strains and high strain rates borne by both alloys due to the impact of the Al flyer sheet on the steel sheet during the process. The asymmetrical shape of the rectangular joint line entailed a lower magnitude of residual stresses along the short side of the weld.

Electrochemical synthesis of Ti–Al–V alloy by chlorination of Ti2O3 and V2O3 in AlCl3-containing molten chloride salt

Abstract The current study proposes a novel method of preparing Ti–Al–V alloy by electrochemical co-deposition by adding Ti2O3 and V2O3 into the molten salt system. The influence of chlorination of Ti2O3 and V2O3 in KCl–LiCl–MgCl2–AlCl3 melt was studied by inductively-coupled plasma emission spectrometer (ICP-AES) and X-ray diffractometer (XRD). The results revealed that the optimal chlorination temperature ranged from 600 °C to 700 °C and the main chlorination products were TiCl3, VCl3, and Al2O3 byproduct. The electrochemical behavior of Ti3+, V3+ and Al3+ in a molten AlCl3-containing chloride salt was investigated by cyclic voltammetry. The stepwise reduction in the cathode could be given as: V3+→V2+, Ti3+→Ti2+, V2+→V, Ti2+→Ti, Ti2+/V2+/Al3+→Ti–Al–V alloy. The electrolytic products were also characterized by XRD and scanning electron microscopy (SEM), equipped with energy dispersive spectroscopy (EDS). The results demonstrated that, as metallic Al was used as an anode, a dendritic Al3Ti alloy and Al sheet were obtained after the addition of Ti2O3 into the KCl–LiCl–MgCl2–AlCl3 melt. However, the presence of both Ti2O3 and V2O3 resulted in fishbone-like Al3Ti, Al3Ti0.8V0.2 and Al3Ti0.666V0.333 alloys, as well as dense granules of metallic Al.

Formation of Nanoporous Gold Film on Ti by Anodization in Oxalic Acid

Abstract A nanoporous gold (NPG) film was formed on a Ti sheet or sputter-deposited thin Ti film by the anodization of a thin gold film on the Ti substrates in oxalic acid. A remarkably low anodic current of the Ti sheet compared with that of the Al sheet indicates that Ti is a stable substrate for the NPG film formed by the anodization. It is also confirmed that the preanodization of the Ti sheet significantly improves the adhesion of the NPG film to Ti. By increasing the anodic potential, NPG film was formed on sputter-deposited thin Ti film with a thickness of 130 nm.

3D X‐Ray Diffraction Characterization of Grain Growth and Recrystallization in Rolled Braze Clad Aluminum Sheet

Braze clad on aluminum (Al) sheets has enabled fast and convenient brazing assembly of complex heat exchangers. However, there are details in the brazing process that are not fully understood. Herein, 3D X‐ray diffraction (3DXRD) is used to investigate the grain position, size, and orientation before and after controlled atmosphere brazing (CAB). The outcomes are presented as maps of center‐of‐mass positions with relative grain size distribution and color‐coded grain orientations. The results show that, for braze clad Al sheets exposed to CAB simulation, it is possible to distinguish grains from the solidified AlSi alloy from those in the core Al alloy. It is also possible to distinguish new grains obtained through recrystallization during CAB. Hence, the study shows that stretching of the rolled Al sheet by 6% provides enough stored energy in the core material so that recrystallization occurs during CAB and, in addition, provides conditions for AlSi alloy grain growth into the core material. While the phenomenon is well known, it is poorly understood for processes in connection with brazing of mechanically formed Al alloy components in heat exchanger assemblies, and these results demonstrate the potential for gaining deeper insights through 3DXRD.

Influence of Fe and Mn on the Microstructure Formation in 5xxx Alloys-Part I: Evolution of Primary and Secondary Phases.

The increasing demands for Al sheets with superior mechanical properties and excellent formability require a profound knowledge of the microstructure and texture evolution in the course of their production. The present study gives a comprehensive overview on the primary- and secondary phase formation in AlMg(Mn) alloys with varying Fe and Mn additions, including variations in processing parameters such as solidification conditions, homogenization temperature, and degree of cold rolling. Higher Fe alloying levels increase the primary phase fraction and favor the needle-shaped morphology of the constituent phases. Increasing Mn additions alter both the shape and composition of the primary phase particles, but also promote the formation of dispersoids as secondary phases. The size, morphology, and composition of primary and secondary phases is further affected by the processing parameters. The average dispersoid size increases significantly with higher homogenization temperature and large primary particles tend to fragment during cold rolling. The microstructures of the final soft annealed states reflect the important effects of the primary and secondary phase particles on their evolution. The results presented in this paper regarding the relevant secondary phases provide the basis for an in-depth discussion of the mechanisms underlying the microstructure formation, such as Zener pinning, particle stimulated nucleation, and texture evolution, which is presented in Part II of this study.

Microstructure, texture and mechanical properties of sandwiched ARB6/2/6 2N Al fabricated by accumulative roll bonding

Two-cycle accumulative roll bonding (ARB) process was applied to produce sandwiched 2N–Al (99.2% purity) sheets (referred as ARB6/ARB2/ARB6) initially containing 2-cycle ARB processed core-layers (shorted as ARB2 layer) with coarse grains and 6-cycle ARB processed outer-layers (shorted as ARB6 layer) with fine grains. The ARB6/ARB2/ARB6 (shorted as ARB6/2/6) sheets were further annealed at various temperatures. The effect of annealing process on the microstructures and mechanical properties of the sandwiched samples were systematically studied and compared with a conventional 6-cycle ARB processed 2N Al sample (shorted as ARB6). The grain size in the ARB2 layer is larger than that in the ARB6 layers in ARB6/2/6 due to the lower strain in the ARB2 layer. During annealing, the grain growth rate in the ARB6 layers is faster than that of the ARB2 layer. The ultimate tensile strength and uniform elongation of ARB6/2/6 are 219 MPa and 2.4%, respectively. It is found that ARB6/2/6 have similar normalized strengths to ARB6, but the normalized elongation of ARB6/2/6 is much larger than those of ARB6, which is in consistent with other materials with heterogeneous structures.

A stable and plug-and-play aluminium/titanium dioxide/metal-organic framework/silver composite sheet for sensitive Raman detection and photocatalytic removal of 4-aminothiophenol

The sensitive detection and rapid removal of 4-aminothiophenol (4-ATP, a poisonous pesticide) demand special design to potential substrates. Herein, a metal-organic framework (ZIF-8) and Ag nanoparticles were fabricated one by one on the TiO2 coated Al sheet, and thus the Al–TiO2-ZIF-8-Ag sheet with sandwich structure was successfully synthesized. The cost-effective Al–TiO2-ZIF-8-Ag sheet (3.7 wt% Ag) possessed a low detection concentration of 1 × 10−9 M towards 4-ATP, and surface-enhanced Raman scattering (SERS) analytical enhanced factor (AEF) of the Al–TiO2-ZIF-8-Ag was 2.6 × 106, which was higher than other similar substrates. Furthermore, 4-ATP can be selectively and repeatedly detected on the Al–TiO2-ZIF-8-Ag even through it was in real samples. It indicated that the Al–TiO2-ZIF-8-Ag was a very active and stable SERS materials for the monitoring of 4-ATP. Importantly, the substrate exhibited faster and more efficient photocatalytic activity for 4-ATP degradation. The SERS and photocatalytic mechanisms of 4-ATP on the Al–TiO2-ZIF-8-Ag substrate were proposed. The cost-effective Al–TiO2-ZIF-8-Ag sheet with double function is plug-and-play, and could be used in the detection and treatment of pollutants in wastewater.

Spot welding of Al-Cu sheets using the electromagnetic pulse for improving the quality of joints

The aim of the present research is to join Al and Cu sheets using the electromagnetic spot welding (EMSW) by placing a perforated insulator mask between the sheets. For this purpose the key parameters of voltage (V), thickness of mask (tm ), thickness of driver (td ) and diameter of mask hole (D) were considered in order to improve the mechanical properties of Al-Cu spot weld, simultaneously. In order to evaluate the quality of spot welds, the microstructure of weld interface was studied by optical and scanning electron microscopy (SEM). The improvement of mechanical properties of Al-Cu spot welds was achieved by applying the optimal values of significant parameters. The microstructure analysis of Al-Cu spot weld at the desirable values of parameters indicated that the interface defects and intermetallic layers were reduced to a minimum value.

A virtual materials testing approach to calibrate anisotropic yield functions for the simulation of earing during deep drawing of aluminium alloy sheet

We present a pragmatic and computationally efficient scheme to combine polycrystal-plasticity models based on crystallographic texture with phenomenological yield functions into a multilevel modelling framework for consideration of the anisotropic materials response during finite-element (FE) simulations of forming operations. Materials tests are conducted virtually using the visco-plastic self-consistent (VPSC) polycrystal-plasticity model to provide the stresses and strain ratios in uniaxial tension, plane-strain tension and under balanced biaxial conditions. These anisotropic materials data are then utilized to calibrate an advanced phenomenological yield function, viz. Yld2011–27p due to Aretz and Barlat, to simulate the anisotropic materials behaviour during subsequent sheet metal forming operations, here, deep-drawing. Since the simulated materials data can be used just as experimental values, no special fitting procedure for the yield function is required and validation of the simulation results is straightforward. Moreover, the followed modelling scheme enables to combine materials data obtained from experimental and virtual tests in a so-called hybrid approach. The modelling scheme was validated by FE-simulations of the earing behaviour of various Al sheet alloys, including AA 1200-O, AA 3104-H19, AA 5182-O and AA 5050A-H44, with distinctively different textures. Since earing is almost entirely controlled by crystallographic texture, analysis of the earing behaviour provides for a meaningful but demanding proof-of-principle for the current hierarchical modelling scheme.

A patterned aluminum/reduced graphene oxide/silver sheet for detection and degradation of malachite green in water

A patterned reduced graphene oxide/silver nanoparticles assembled on Al sheet was facilely fabricated using layer-by-layer assembly combined with thermal reduction. The plug-and-play composite sheet shows stable and reproducible performance for SERS detection and catalytic degradation for a toxic malachite green. • A patterned RGO and Ag nanoparticles were facilely assembled on Al sheet. • The sheet was highly active for detection and degradation towards malachite green. • The cost-effective sheet with double functions was stable and reproducible. • The patterned RGO was very significant to the high performance of the sheet. In this work, a patterned reduced graphene oxide (RGO)/silver nanoparticles on Al sheet was prepared using layer-by-layer assembly technique. The morphology, structure and composition of the Al/RGO/Ag were investigated using SEM, XRD and XPS. It showed that there existed a strong interaction among Al, the patterned reduced graphene oxide and Ag nanoparticles in the Al/RGO/Ag sheet, which made the patterned Al/RGO/Ag sheet be as a sensitive SERS material for rapidly monitoring trace malachite green with good reproducibility and high stability. Also, the plug and play Al/RGO/Ag sheet exhibited high and stable catalytic degradation activity for malachite green. The constructed bifunctional sheet will provide some references for designing those materials used in detection and degradation of contaminants in wastewater.

Fatigue Strength of Rivet Resistance Spot Welding Technique in Comparison with Self-Piercing Riveting for Multi-material Body-in-White Structure

Cost-efficient multi-material design requires suitable joining techniques, ideally with low investment cost by re-using existing assembling lines. The recently developed resistance rivet spot welding (RRSW) technique combines mechanical joining with spot welding and enables cost-efficient joining of aluminum (Al) to steel for multi-material body-in-white structures. Here, the static and fatigue strengths of different hybrid Al-steel specimens made by RRSW were measured and compared to other state-of-the-art joining techniques, such as self-piercing riveting (SPR) and RSW. The static strength of RRSW matched or exceeded that of SPR regardless of the sheet thickness, whereas the fatigue strength of the RRSW joints showed a strong dependency on the thickness of the steel sheets. For thinner steel sheets, the fatigue of the RRSW-joined metal sheets was lower in comparison with SPR. Fatigue cracks were initiated in thin steel sheets around the weld nugget. By contrast, for thicker steel sheets, the fatigue strength of RRSW matched or exceeded that of SPR. With a thicker material combination of 1.5 mm steel and 1.0 mm Al, fatigue cracks occurred only in the Al sheet in both SPR and RRSW. For suitable steel sheet thickness, RRSW is thus a durable technique to join steel and Al.

Flexible/Bendable Acoustofluidics Based on Thin-Film Surface Acoustic Waves on Thin Aluminum Sheets.

In this paper, we explore the acoustofluidic performance of zinc oxide (ZnO) thin-film surface acoustic wave (SAW) devices fabricated on flexible and bendable thin aluminum (Al) foils/sheets with thicknesses from 50 to 1500 μm. Directional transport of fluids along these flexible/bendable surfaces offers potential applications for the next generation of microfluidic systems, wearable biosensors and soft robotic control. Theoretical calculations indicate that bending under strain levels up to 3000 με causes a small frequency shift and amplitude change (<0.3%) without degrading the acoustofluidic performance. Through systematic investigation of the effects of the Al sheet thickness on the microfluidic actuation performance for the bent devices, we identify the optimum thickness range to both maintain efficient microfluidic actuation and enable significant deformation of the substrate, providing a guide to design such devices. Finally, we demonstrate efficient liquid transportation across a wide range of substrate geometries including inclined, curved, vertical, inverted, and lateral positioned surfaces using a 200 μm thick Al sheet SAW device.

Stationary Shoulder Friction Stir Assisted Scribe Technique for Dissimilar Joining

Abstract We report on implementation of a stationary shoulder in dissimilar joints of Al-steel and Al-carbon fiber reinforced polymer (CFRP) using friction stir assisted scribe technology (FaST). Viable joint strength similar to the conventional FaST process was demonstrated in Al-Steel. A significant improvement in as-welded surface roughness for both Al-steel and Al-CFRP cases was also achieved. Interrupted lap shear tests performed on Al-steel joints and a corresponding computational model indicate the joint failure typically occurs in Al sheet via a crack that originates at the steel hook tip on the loading side. A similar fracture path was observed in an Al-CFRP joint.