Article

Aluminium: The metal of choice

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Abstract

This article summarizes the importance of aluminium as the metal of choice for many applications. Aluminium is a lightweight, durable metal. It is silvery in appearance when freshly cut, is a good conductor of heat and electricity, and is easily shaped by moulding and extruding. Aluminium has two main advantages when compared with other metals. Firstly, it has a low density, about one-third that of iron and copper. Secondly, although it reacts rapidly with the oxygen in air, it forms a thin, tough and impervious oxide layer that resists further oxidation. This removes the need for surface-protection coatings such as those required with other metals, in particular with iron. All the indications are that the growth in the use of aluminium will likely accelerate. It is expected that in the near future the use of aluminium with specifically improved properties will grow in many applications, meeting the increased economic and ecological demands. Considering the entire life-cycle of an automobile, from the extraction of materials to the final disposal, including recycling and reuse applications, aluminium proves to be a potential alternative to steels in future automotive applications.

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... For instance, the elastic limit of the aluminum is 280 MPa. 51 Hence, the fabricated aluminum specimen is mechanically strained to a maximum tensile load of 160 MPa with a strain rate of 1 mm min −1 using a uniaxial tensile machine, as shown in Figure 6a. As a resultant of applied tensile force, the aluminum specimen experiences the strain (ε) and it is transmitted to the bonded flexible strain sensor in which electrical conductive network formed by the HEG nanofillers gets distorted. ...
... For instance, the elastic limit of the aluminum is 280 MPa. 51 Hence, the fabricated aluminum specimen is mechanically strained to a maximum tensile load of 160 MPa with a strain rate of 1 mm min −1 using a uniaxial tensile machine, as shown in Figure S1f. The resultant change in the electrical resistance value is simultaneously measured using a Keithley 2450 source measurement unit. ...
Article
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In recent times, flexible piezoresistive polymer nanocomposite-based strain sensors are in high demand in wearable devices and various new age applications. In the polymer nanocomposite-based strain sensor, the dispersion of conductive nanofiller remains challenging due to the competing requirements of homogenized dispersion of nanofillers in the polymer matrix and retaining of the inherent characteristics of nanofillers. In the present work, waterproof and flexible poly(vinylidene difluoride) (PVDF) with a polymer-functionalized hydrogen-exfoliated graphene (HEG)-based piezoresistive strain sensor is developed and demonstrated. The novelty of the work is the incorporation of polystyrene sulfonate sodium salt (PSS) polymer-functionalized HEG in a PVDF-based flexible piezoresistive strain sensor. The PSS-HEG provides stable dispersion in the hydrophobic PVDF polymer matrix without sacrificing its inherent characteristics. The electrical conductivity of the PVDF/PSS-HEG-based strain sensor is 0.3 S cm–1, which is two orders of magnitude higher than the PVDF/HEG-based strain sensor. Besides, near the percolation region, the PVDF/PSS-HEG shows a maximum gauge factor of 10, which is about two times higher than the PVDF/HEG-based flexible strain sensor and 5-fold higher than the commercially available metallic strain gauge. The enhancement in the gauge factor is due to the stable dispersion of PSS-HEG in the PVDF matrix and electron conjugation caused by the adherence of negatively charged sulfonate functional groups on the HEG. The developed waterproof flexible strain sensor is demonstrated using portable wireless interfacing device for various applications. This work shows that the waterproof flexible PVDF/PSS-HEG-based strain sensor can be a potential alternative to the commercially available metallic strain gauge.
... Aluminum is a metal that is lightweight and durable, silver when cut, good conductor of heat and electricity, and easily formed by molding and extrusion. Aluminum also has excellent thermal properties and corrosion resistance has its use in air conditioning, cooling and heat exchange systems [2]. Utilization of aluminum waste from used beverage cans to produce hydrogen gas. ...
... W = E x I x t (2) [16] Where -W = Mass -E = Valence -I = Current ...
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The production of hydrogen gas as an alternative fuel cell which is a renewable energy, is now in great demand by utilizing waste aluminum beverage cans and added water using NaOH catalyst by electrolysis process. The research method will be carried out by inserting 1 gram of aluminum pieces into a tube and 300 ml of distilled water followed by a NaOH catalyst. Both faucets are opened to release air during the filling process. The faucet is closed when the height of the solution in both tubes is the same. Then turn on the DC flow, then adjust the voltage according to the variable. The filling period is recorded until the specified reaction time. The results of the gas volume obtained are recorded, and the hydrogen obtained is determined by the flame test. From the research it can be concluded that the hydrogen gas produced from the reaction can be identified by means of a flame test. The characteristics of hydrogen gas appear in flames which tend to disappear in the air. At Al 5 gr Weight : 5 M NaOH concentration is the largest volume of hydrogen. The reaction time of 150 minutes will produce a lot of hydrogen gas. The largest volume of hydrogen gas lies at a voltage of 20 volts.
... Aluminum alloys are widely used in the aviation and automotive industries, shipbuilding and instrumentation, rocket technology and construction [2], for example, aluminum alloys make up to 30 -35 % of aircraft materials. In modern aircraft, aluminum is used literally everywhere: in the fuselage, flaps, wing and tail structures, etc. [3]. ...
Article
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Despite being widely used in such industries as chemical, aviation and food ones, aluminum and its alloys are known to beprone to localized corrosion, and this remains a problem to be solved, especially when it comes to pitting corrosion. Therefore,there is a necessity to detect traces of corrosion at the earliest stages and to quantify the extent of corrosion damage. Thesimplest solution for assessing the overall corrosion rate is to use the gravimetric method, which, however, does not provideinformation for assessment of localized corrosion. This paper is devoted to the consideration of the possibilities of usingthe method of confocal laser scanning microscopy (CLSM) for assessing corrosion resistance using high-purity aluminum.The CLSM method, due to its high resolution (especially along the vertical axis), enables to obtain quantitative data on thevolume of corroded metal, determine the depth of corrosion damage including building their profilograms, and analyze themorphology of the surface damaged by corrosion. Owing to the high sensitivity of the CLSM method, corrosion losses weredetected within 21 days, contrary to the standard gravimetric method, which failed to determine the loss of metal even after160 days of corrosion testing
... 9,10 The preparation of the bonding surfaces is of special importance since each type of surface impurities may disturb the required quality level of the joint. 11 Due to the tendencies of Al and Cu to oxidize under ambient conditions, [12][13][14] it is recommended that the cleaning of the contact surfaces of these metals should be performed immediately before the welding procedure. In addition to the superficial impurities, the quality of an Al/Cu joint may be affected by the impurities present in the volumes of Al and Cu, which, apart from affecting the conductivity of the basic materials, might also induce a production of various compounds at the very joint during the welding procedure, subsequently increasing the local contact resistance upon applying the Al/Cu bonding elements. ...
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The objective of this research is to consider the effects of certain parameters of the friction-welding process on the morphology of an aluminum/copper joint. The effect of the following parameters was monitored: the operating time, the operating pressure, the forging time and the forging pressure. The speed was constant during the binding process and reached 1500 min-1. The preparation of the welding materials was performed in accordance with the industrial production conditions. With the SEM-EDS analysis, it was found that the morphology of the Al/Cu interface slightly changes when we change the distance from the rotation axis, irrespective of the combination of the friction-welding parameters. Apart from this, the joined effects of the operating pressure of 48 MPa and the forging pressure of 160 MPa caused a morphological change of the Al/Cu interface, while the forging time at the moment of the combined pressurizing effect significantly influenced the modification of the Al/Cu interface shape within a very narrow time interval of only a few seconds.
... Protective layers based on silicide-aluminide phases prepared from the liquid phase were studied by various authors [1][2][3][4] and were shown to exhibit the potential of acting as protective layers where titanium and its alloys are used in high-temperature applications. [5][6][7][8][9][10][11][12][13] The principle of the method is based on the high affinity of silicon and aluminium to titanium. ...
Article
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The method of coating with silicon from the liquid phase (also called the hot-dip method) was presented by several authors who indicated that this was an effective and inexpensive technique capable of producing Ti-Al-Si layers on titanium. and titanium-alloy substrates that are rich in ternary phases. The present study examines the effects of the preparation conditions on the structure and properties of the layers. These layers provide excellent protection from high-temperature oxidation, even at a temperature of 950 degrees C. It was proved with SEM and X-ray analyses that the original tau(2) ternary phase almost completely decomposed into pure Ti5Si4 and TiSi silicides at the temperature of 950 degrees C. The formed layer, consisting of silicide sub-layers, exhibited superior protective properties in high-temperature applications.
... 6 Chloride ions are greatly absorbed on the natural oxide film and cause deep ruptures into the surface. 7 The generation of these ruptures and the dissolution of the oxide phases disrupt the film continuity and cause the propagation of corrosion. To overcome the corrosion-related problems, the interaction of the surface and corrosive environment must be disconnected. ...
Article
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Micro-arc oxidation (MAO) is an attractive process for the fabrication of protective coatings on aluminum alloys used in many industrial applications, such as automotive, structural and aerospace. However, improvements in the corrosion resistance of aluminum alloys upon covering their surfaces with MAO coating may not be sufficient for extending the service life of the components utilized in harsh environments. In the present study, the MAO coating formed on a 6061 aluminum alloy was sealed using a stearic acid treatment. In the scope of the present study, the surface and cross-sectional microstructures and the phases of the MAO coatings were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, respectively. The wettability and surface roughness of the samples were measured by goniometer and profilometer, respectively. The corrosion resistance was assessed by long-term immersion in 3.5 % of mass fractions NaCl solution. Finally, it is concluded that sealing of the MAO coating by stearic acid treatment significantly improved the corrosion resistance of the 6061 quality aluminum alloy as compared to the untreated state and the unsealed MAO state.
... Metals such as steel represent an integral part of our lives in several areas in which they operate (Badr, 2009;Gándara, 2013). They are abundant, have excellent mechanical properties, easily recyclable and relatively low cost. ...
... Aluminium is the most abundant metal in the Earth's crust and the second most commonly used metal in the world. Because of its lightness, electrical conductivity and corrosion resistance, it is used in a variety of products, including vehicles, buildings, furniture, cans, electronic gadgets and many others (Freiría Gándara, 2013). The aluminium industry is among the highest energy intensive industries, with a consumption of around 4 % of the global electricity output (Tyabji and Nelson, 2012) and thus produces large amounts of greenhouse gas (GHG) emissions. ...
Article
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The aluminium industry is one of the largest emitters of greenhouse gases (GHG) and accounts for approximately 1 % of global GHG emissions. A large portion of emissions are indirect emissions, due to the large GHG footprint of consumed electricity, while direct energy and process-related emissions are also significant. The aluminium is widely used in packaging, transportation, the building sector and for various other purposes. This study focuses on aluminium slugs, which are semi products made from aluminium alloys and are used as tubes and containers in the pharmaceutical, food and cosmetic industries. Since the aluminium industry is among the largest GHG emitters, a Life Cycle Assessment (LCA) was performed to evaluate the environmental impact of aluminium slug production. Environmental impact assessment was performed using OpenLCA software, the Ecoinvent 3.1 database and self-collected plant data. The study includes the environmental impact of anode production, electrolysis and slug production. The functional unit for the study is 1 t of aluminium slug at the company exit gate. Besides GHG emissions and the related GHG footprint associated with slug production, acidification potential and photochemical oxidation potential are further assessed. Various opportunities for GHG emission reduction are further investigated in accordance with the longer-term company strategy. If more aluminium scrap were used and carbon capture performed, the GHG footprint could be reduced by 65 % compared to the base case.
... Aluminum and its alloys have enormous applications in the automotive, electrical as well as in the aerospace industries [1,2]. Due to this, the surfaces of aluminum and its alloys are often exposed to reactive liquids and oils in various situations, which can induce surface tarnishing, corrosion and fouling thereby reducing their time-span of usefulness. ...
... Recycling does not degrade the aluminium properties since it has the same atom structure. Highly recyclable properties of aluminium make it a choice for sustainable material [7]. Fig. 1 shows how the aluminium is conserved and recycled. ...
Article
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Recycling of industrial waste is a subject of great importance today in any sector and more so in the aluminium industry. Aluminium recycling could sustain material resources, reduce the usage of energy, ease greenhouse gas emission and save the environment. This study examines the usage of direct hot extrusion of aluminium chip in the recycling of aluminium, focusing on the end product, properties and processing route. The process directly converts the new scrap of aluminium chips generated from industries to aluminium-based composite or aluminium alloys. The properties of the extrudates depend on the process parameters and the alloying elements added to the aluminium chips. High shear strain is required to disperse the oxide layer on the surfaces of the chip, thus permitting a contact between the newly exposed aluminium chips, and is consolidated to form a solid semi-finished product. The technique can be done through various process combinations and routes. The selection of process combination and routes depends on the product type and properties, degree of contamination of chip and size. The technique is proven as a viable method for aluminium recycling.
... The TGA curve of HVOF thermal spray aluminium coated PBO fibres is shown in Figure 5. 15 ...
Article
This novel research work reports the possibility of using a high-performance polymer fiber as a potential reinforcement in a suitable metal matrix for the development of composites. The manufacturing route is an additive process using High-Velocity Oxy-Fuel Thermal-Spray technique. Continuous strands of Poly-benzobisoxazole and para-aramid were used as high-performance polymer reinforcement in a uni-directional configuration, and Zinc metal was used as matrix material. The developed Thermal-Spray composites were subjected to mechanical tensile test and characterized by Scanning Electron Microscopy and Optical Microscopy. The results of the tensile tests revealed a substantial increase in the tensile properties and the investigation of Scanning Electron Microscopy and optical images showed a good deposition of matrix material on the reinforcing polymer fibers. The testing and characterization results were conclusive of the fact that Poly-benzobisoxazole and para-aramid can be used as an effective reinforcement even at low volume content for high strength structural applications.
... Aluminum (Al) is widely used in the aerospace, architectural construction, and marine and chemical industries, as well as many domestic uses, because it is light, conductive, and corrosion-resistant metal [1]. Primary Al is produced from bauxite ore through Bayer's process; however, this method is not applicable in the processing of low-grade bauxite because of low alumina extraction and massive red mud production [2]. ...
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Filamentous fungi have been proved to have a pronounced capability to recover metals from mineral ores. However, the metal recovery yield is reduced due to toxic effects triggered by various heavy metals present in the ore. The current study highlights the fungal adaptations to the toxic effects of metals at higher pulp densities for the enhanced bio-recovery of aluminum from low-grade bauxite. In the previous studies, a drastic decrease in the aluminum dissolution was observed when the bauxite pulp density was increased from 1 to 10% (w/v) due to the high metal toxicity and low tolerance of Aspergillus niger and Penicillium simplicissium to heavy metals. These fungi were adapted in order to increase heavy metal tolerance of these fungal strains and also to get maximum Al dissolution. A novel approach was employed for the adaptation of fungal strains using a liquid growth medium containing 5% bauxite pulp density supplemented with molasses as an energy source. The mycelia of adapted strains were harvested and subsequently cultured in a low-cost oat-agar medium. Batch experiments were performed to compare the aluminum leaching efficiencies in the direct one-step and the direct two-step bioleaching processes. FE-SEM analysis revealed the direct destructive and corrosive action by the bauxite-tolerant strains due to the extension and penetration of the vegetative mycelium filaments into the bauxite matrix. XRD analysis of the bioleached bauxite samples showed a considerable decline in oxide minerals such as corundum and gibbsite. Results showed a high amount of total Al (≥ 98%) was successfully bioleached and solubilized from low-grade bauxite by the adapted fungal strains grown in the presence of 5% pulp density and molasses as a low-cost substrate. Graphical abstract
... Aluminum materials are resistant to corrosion caused by water and road salts, even if they are unpainted or uncoated. Aluminum is stainless and corrosion resistant, such as steel, if the paint is scratched or removed (Stojanovic et al. 2018;Gándara, 2013). ...
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Objective: In this study, it is aimed to evaluate the effect of the glass ceiling syndrome in female health care professionals on their organizational justice perception and to examine the factors affecting organizational justice perception and glass ceiling syndrome.
... The maximum load which can be applied for testing is determined by the elastic limit of the specimen under investigation. For instance, the elastic limit of the aluminium is 280 MPa [47]. Hence, the fabricated aluminium specimen is mechanically strained to the maximum tensile load of 160 MPa with the strain rate of 1 mm min −1 using a uniaxial tensile machine (UTM). ...
Article
In the background of designing a polymer nanocomposite based flexible strain sensors, homogenized dispersion of nanofillers remain challenging due to the trade-off between upholding of inherent characteristics of nanofillers and stable dispersion of nanofillers in the polymer matrix. This study provides an approach of balancing the stable dispersion of nanofillers and maintain the inherent characteristics of nanofibers by the method of polymer functionalization. Herein, two oppositely charged polymers polystyrene sulfonate sodium salt (PSS) and poly-diallyl-dimethyl-ammonium chloride (PDDA) are used separately to functionalize the multiwalled carbon nanotubes (CNT) and it dispersed in poly (vinylidene difluoride) (PVDF) polymer matrix to get flexible nanocomposite strain sensor to investigate both electrical conductivity and the gauge factor. PSS functionalized CNT (PSS-CNT) shows better dispersion than the PDDA-CNT in PVDF matrix. Besides, the electrical conductivity of PVDF/PSS-CNT (0.44 ± 0.02 Scm⁻¹) is about 28 times higher than the PVDF/PDDA-CNT, and the gauge factor of PVDF/PSS-CNT (9.8 ± 0.3) is 2-fold higher than the PVDF/PDDA-CNT. The stable dispersion of PSS-CNT is due to the repulsive nature existing between the individual CNTs caused by the attachment of charged polymer functional groups as same as intrinsic functional groups of the pristine CNT. This work signifies the role of synergy between the charged particles in the functional groups and charged nature of the filler influencing the performance of flexible strain sensors. The detailed investigation using various techniques reveals significance of selection of suitable polymers for functionalization by showing its influence in the context of designing the high-performance flexible strain sensor.
... Parmi les nombreux attributs et qualités expliquant sa popularité croissante, on cite sa malléabilité, sa résistance à l'oxydation et sa faible densité (Gourier-Fréry et Fréry, 2004). On le trouve sous forme combinée dans différents minéraux, principalement la bauxite (Gándara, 2013). Il est également utilisé dans l'industrie et se retrouve de ce fait dans les aliments, les produits cosmétiques, et même les médicaments (Exley et House, 2011). ...
Article
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Omniprésent dans notre vie quotidienne, l’aluminium (Al) est l’un des éléments traces métalliques les plus dangereux pour la santé humaine. Nous y sommes exposés quotidiennement, par l’alimentation, l’application d’antitranspirants, l’utilisation d’antiacides, la vaccination, etc. L’exposition est donc inévitable, et chaque jour des taux modérés de ce métal pénètrent dans l’organisme et sont capables de s’accumuler dans certains organes. Malgré cela, la majorité de la population humaine n’est pas à risque évident de toxicité aluminique, puisque notre corps est équipé de plusieurs mécanismes qui ne permettent pas une absorption et une accumulation faciles, et facilitent son élimination. Par conséquent, une très faible quantité d’Al atteindra les différents organes et tissus (poumons, foie, cerveau, etc.). Une exposition élevée à l’Al entraîne des effets toxiques pulmonaires, gastro-intestinaux, cardiovasculaires, hématologiques, musculosquelettiques, neurologiques, hépatopancréatiques, etc. Les populations les plus exposées sont les patients dialysés, les consommateurs d’antiacides à long terme, et les professionnels de l’Al.
... Aluminium is among the most prevalent and widespread metals in our environment (Hardisson et al., 2017). It is widely used in commercial as well as domestic applications (kitchenware) Gándara, (2013). Humans are exposed to aluminium from various sources, such as diet, which accounts for 95% of body aluminium, drinking water, air, cosmetics, and medical drugs, primarily antacids (Skalny et al., 2021). ...
Article
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Neurodegeneration leads to the loss of structural and functioning components of neurons over time. Various studies have related neurodegeneration to a number of degenerative disorders. Neurological repercussions of neurodegeneration can have severe impacts on the physical and mental health of patients. In the recent past, various neurodegenerative ailments such as Alzheimer’s and Parkinson’s illnesses have received global consideration owing to their global occurrence. Environmental attributes have been regarded as the main contributors to neural dysfunction-related disorders. The majority of neurological diseases are mainly related to prenatal and postnatal exposure to industrially produced environmental toxins. Some neurotoxic metals, like lead (Pb), aluminium (Al), Mercury (Hg), manganese (Mn), cadmium (Cd), and arsenic (As), and also pesticides and metal-based nanoparticles, have been implicated in Parkinson’s and Alzheimer’s disease. The contaminants are known for their ability to produce senile or amyloid plaques and neurofibrillary tangles (NFTs), which are the key features of these neurological dysfunctions. Besides, solvent exposure is also a significant contributor to neurological diseases. This study recapitulates the role of environmental neurotoxins on neurodegeneration with special emphasis on major neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease.
... Aluminum is the second most widely used metal in the world [64]. Hence, many researchers have paid a great deal of attention to optimizing its consumption for various purposes [65][66][67][68]. ...
Article
This study has two major aims, first, to compare the electrocoagulation (EC) system for Ni²⁺ removal from aqueous solution using direct current (DC) versus alternating current (AC), and second, to optimize the process for each type of current. For this purpose, four variables of current density, initial nickel concentration, initial pH of the solution, and reaction time, alongside three responses of remaining nickel, energy consumption, and electrode (aluminum) consumption, were considered. Accordingly, 30 experiments designed by the response surface methodology (RSM) based on the central composite design (CCD) were carried out for each mode. The statistical analysis revealed that the quadratic models proposed by the Design Expert are reliable to predict the outcomes. As quantitative results for the DC and AC modes, the average amount of the remaining nickel was 44.06 and 43.91 mg/L, energy consumption was 34.9 and 29.2 kWh/kg Ni removed, and electrode consumption was 2.3 and 1.2 kg Al/kg Ni removed, respectively. Thus, the transition from conventional DC to AC waveform coagulation led to a more than 16% reduction in energy consumption and approximately 47% depletion in electrode consumption.
... Aluminum, a corrosion-resistant metal, has light weight and density, high electrical and thermal conductivity, and high ductility and is easily deformable. For this reason, it is used in aerospace industries, transportation industries, packaging and food industries, building and construction, electrical industries, a wide range of home household and appliances, machinery and equipment, and monetary currency like aluminum coins [11,13]. ...
Article
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Aluminum poisoning has been reported in some parts of the world. It is one of the global health problems that affect many organs. Aluminum is widely used daily by humans and industries. Residues of aluminum compounds can be found in drinking water, food, air, medicine, deodorants, cosmetics, packaging, many appliances and equipment, buildings, transportation industries, and aerospace engineering. Exposure to high levels of aluminum compounds leads to aluminum poisoning. Aluminum poisoning has complex and multidimensional effects, such as disruption or inhibition of enzymes activities, changing protein synthesis, nucleic acid function, and cell membrane permeability, preventing DNA repair, altering the stability of DNA organization, inhibition of the protein phosphatase 2A (PP2A) activity, increasing reactive oxygen species (ROS) production, inducing oxidative stress, decreasing activity of antioxidant enzymes, altering cellular iron homeostasis, and changing NF-kB, p53, and JNK pathway leading to apoptosis. Aluminum poisoning can affect blood content, musculoskeletal system, kidney, liver, and respiratory and nervous system, and the extent of poisoning can be diagnosed by assaying aluminum compounds in blood, urine, hair, nails, and sweat. Chelator agents such as deferoxamine (DFO) are used in the case of aluminum poisoning. Besides, combination therapies are recommended.
... Protective layers based on silicide-aluminide phases prepared from the liquid phase method were studied by various authors [1][2][3][4] and have been demonstrated to possess the potential of acting as protective layers where titanium and its alloys serve in high-temperature applications [5][6][7][8][9][10][11][12][13]. The principle of the method is based on high affinity of silicon and aluminium to titanium. ...
Article
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Metoda křemíkování z kapalné fáze je jednoduchá a efektivní metoda pro přípravu vrstev tvořených intermediálními fázemi Ti-Al-Si na titanu a slitinách titanu, založených na reakci vzorků ponořených do tavenin Al-Si. Tyto vrstvy mají uplatnění především při vysokoteplotních aplikacích jako ochranné vrstvy. Touto metodou lze připravit kompaktní, masivní vrstvy bez pórů a trhlin, při teplotách 650 °C po dobu 60 min lze připravit vrstvy s tloušťkou 60 μm. V tomto příspěvku jsou shrnuty důležité poznatky o vlastnostech vrstev připravených metodou křemíkování z kapalné fáze.
... Aluminum 7075-T6 has been chosen as the fixed material for the designated structure frames. This is because Aluminum 7075-T6 is said to be used where high strength is critical and where good corrosion resistance is not important [27]. ...
... The TGA curve of HVOF thermal spray aluminium coated PBO fibres is shown in Figure 5. 15 ...
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In the quest of novel, reasonable and effective reinforcement, it is very hard to find rare combination of materials which attempts to accord and benefit each other. The exhausted waste spent catalyst from petroleum industries is experimented as a reinforcement obliging to the concept of reuse and recycle. In this investigation, aluminium metal matrix nano composite is to be synthesized by double stir casting method. Pure aluminium and Spent Alumina Catalyst (SAC) is chosen as matrix and primary reinforcement respectively. Nano CuO is added as secondary reinforcement to enhance the mechanical properties of aluminium spent alumina catalyst composite. The composites are synthesized as such, 10% SAC is reinforced to pure aluminium and the amount of nano CuO is varied 0.5%, 0.75%, 1%. Microstructural characteristics of cast composites and tensile samples is studied under Scanning Electron Microscope. There is no clogging of reinforcement materials (nano CuO and SAC) in the aluminium matrix. The mechanical properties of the composites are determined and compared with pure aluminium. There is an impact of dual reinforcement on aluminium matrix which is evident by the improvement in the mechanical properties of the composite. The optimum composition is Al + 10%SAC +1%nano CuO, which resulted in maximum increase in hardness (77%) and tensile strength (78%).
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The present study mainly aspires for assessing the damping characteristics of the nickel electrodeposited A356.2 alloy. Surface modification of the base A356.2 alloy is carried out through nickel electrodeposition by employing a customary stirred watts bath. The damping behaviour of both nickel plated and un-plated aluminium alloy is studied using a dynamic mechanical analyzer (Perkin Elmer-DMA 8000) at three dissimilar frequencies viz. 1, 5 and 10 Hz over a continuous temperature oscillating from the ambient temperature to 150 °C. Nickel plating surface morphology is investigated by employing a scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. The nickel plated specimen’s showcased elevated damping capacities irrespective to the increasing frequencies and temperatures in comparison with the un-plated alloy test specimens. The associated methodologies are reviewed.
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Aluminium is a widely used metal in every sphere of human endeavour. Hence, its corrosion comes as no amazement. Globally, studies are being conducted to suppress this unwanted action of corrosion. Chemical inhibitors are the focus but besides chemical inhibitors, plant extracts could as well be used to inhibit the mechanism of corrosion. Polymeric inhibitors fall under this category. It is believed that these chemical inhibitors should be employed in industrial purposes. They will save millions and produce little to no toxic emission. From findings, the various techniques employed in investigation of corrosion inhibition are weight loss (the fundamental and most common method), electrochemical impedance spectroscopic (EIS) measurements and potentiodynamic polarization.
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In this manuscript a chromium free eco-friendly chemical conversion coating is evaluated for the aluminium components used for the development of optical and electro-optical instruments. Coating is developed for, safer chemical bath, to minimize surface gloss and to enhance surface protection of the aluminium component. Coating process is evaluated for bath formulation and operating parameters. Process is simple and eco-friendly since bath is formulated using minimum and less environmental hazardous chemicals if compared with known similar processes. Developed coating is characterized for optical (reflectance), surface micro-structure (micro-image & roughness), and environmental effects (sea-water corrosion, pH-effect and temperature effect).
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A new experimental study has been conducted on the electrical conduction characteristics of commercially available good conductors subjected to saline water corrosion. More specifically, the corrosion behaviour of two commercially available electrical conductors, namely aluminium and copper in 3.5% sodium chloride solution is first studied at standard room temperature using conventional gravimetric as well as optical micrographic analyses. The corroded conductors are then investigated to determine the effect of exposure time in the corrosive environment on the change in their material properties related to electrical conduction. Measurements of both the dc and ac properties of the conductors are realized in order to analyze them in a comparative fashion, which include material resistivity as well as permittivity and impedance as a function of a wide range of applied frequency. Corrosions of different nature are encountered for the two conductors when exposed to the same corrosive environment, which is, however, verified to cause significant changes in the frequency responses of the materials, especially in the low frequency range.
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Besides advanced nano steels, polymers and ceramics, recently also light metals, i.e., Al, Mg and Ti based materials, have been recognized as future materials for different kinds of advanced applications. Al and its alloys have an acceptable price, excellent corrosive resistance, good mechanical and other physical properties. Therefore, they are also used in the powder-metallurgy (P/M) field. The P/M technology of Al materials is very demanding and has its own specifics compared to the sintering technology of iron and steel. A relatively large quantity of Al-based alloy powder is formed during the sand blasting of slugs and discs in the Talum Al factory, Kidričevo, Slovenia. Therefore, we analysed and investigated its practical usability for a production of advanced products using P/M technology. The formed Al-based powder was compared with the commercially available Al-based powders that are generally used for conventional sintering technology. In the first part of this paper we explain which types of Al-based powders are used for the production of sintered parts, what the required parameters are and why we considered them. Then, the results of theoretical thermodynamic analyses and investigations of the morphological and microstructural characteristics of the selected commercial Al-based powders are given, as well as their comparison with the Al powder formed during the sand blasting and its potential for P/M applications.
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The properties of the secondary AlSi5Cu1Mg alloy, modified with Sb, Sr or Na, used as a cast housing for the automotive industry were investigated. The alloy was prepared from secondary aluminium and the properties of the material from the castings were determined. Presented here are the results of the mechanical tests of the as-cast and heat-treated material (T6), metallographic investigations and EDS analyses of the intermetallic phases based on Fe as well as electrochemical corrosion tests in a solution of 3 % NaCI. In the microstructure and with respect to the corrosion resistance of the alloys, modified with Sb, Sr or Na, no important differences were observed. The tests confirmed that the mechanical properties of cast-on bars from secondary aluminium AlSi5Cu1Mg were suitable for the application, only the microporosity of the castings needs to be eliminated through the selection of the proper casting parameters.
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The use of surface behavior diagrams can frequently enhance the understanding of quantitative x‐ray photoelectron and Auger electron spectroscopic measurements. These diagrams have been used to study (1) the adsorption of nitrilotris methylene phosphonic acid (NTMP), a hydration inhibitor, from aqueous solutions onto aluminum surfaces prepared for adhesive bonding and onto steel surfaces, and (2) the subsequent hydration/corrosion of the oxide or metal when exposed to moist environments. The results show that NTMP coverage increases with inhibitor solution concentration until saturation (monolayer) coverage is achieved. At the same time, NTMP displaces the water initially adsorbed on the oxidized surface. Subsequent exposure of the treated surfaces to moisture results in a slow dissolution of the NTMP, exposing amorphous Al 2 O 3 or Fe 2 O 3 , which rapidly hydrates to AlOOH or FeOOH. Further hydration of the aluminum samples occurs as Al(OH) 3 grows on the surface. These findings indicate that the dissolution of the adsorbed inhibitor is the rate‐limiting step in the hydration/corrosion of oxide‐covered metal surfaces which, in the case of aluminum, is the mechanism of failure of adhesive bonds in a humid environment.
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The Edison Welding Institute (EWI) has recently developed an automotive structures roadmap, with an objective to gain a high level, global view of the drivers and directions of the automotive structures market. The roadmap was developed through dozens of in-person interviews with senior technical staff, designers, materials, researchers, and managers within the original equipment manufacturers (OEM). The National Highway Transportation and Safety Administration (NHTSA) has proposed changes to Federal Motor Vehicle Safety Standard (FMVSS) No. 216, Roof Crush Resistance. There is consensus within the automotive industry that if serious greenhouse gas legislation comes into force at the federal or state level, it could require 60 to 80 mpg fuel economy. The majority of automotive engineers, in light to the high focus on weight reduction, believe that the industry will make a dramatic change toward unibody design.
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The aims of this study were to determine in-vehicle carbon monoxide (CO) levels in major commuting modes in the Metropolitan Area of Mexico City (MAMC) and to identify the main factors affecting the variation in these CO concentrations. CO concentrations were measured inside public and private transport vehicles during the winter of 1991 in Mexico City. Measurements were taken along several commuting routes, during the morning and evening rush hours. Significant differences in CO concentrations were found between different transport modes. The highest CO concentrations were found inside autos and collective taxis, while metro trains, trolleybuses and buses had lower concentrations. In-vehicle CO concentrations in Mexico City were much higher than those reported for previous studies in the U.S.A.
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An aluminum matrix containing titanium carbide particles was fabricated by in situ process in which a carbonaceous gas reacts with titanium in a liquid melt to form TiC.The tensile and yield strength increased by up to 18% after the formation of TiC in the Al alloy matrix. The hardness increased by up to 20%. The abrasive and sliding wear resistance increased with the in situ formation of TiC particles.
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The importance of materials in developing new and improved aerospace systems for the twenty-first century is discussed. Both airframe and engine applications are presented. The materials considered in this paper range from metals such as aluminum, titanium, magnesium, and the superalloys, to intermetallics and metal matrix composites. They also include organic composites covering the spectrum from thermostats to thermoplastics and the emerging molecular level composites. Consideration is also given to ceramics, including reinforced ceramics, refractory metals, and carbon/carbon composites. It is included that we have now left the 'Basic Materials Age' and have entered the 'Era of Engineered Materials'.