Electrical Conductivity Of Aluminum Research Articles

Carbon nanotubes/aluminum interface structure and its effects on the strength and electrical conductivity of aluminum

The contradiction between strength and electrical conductivity of pure aluminum (Al) hinders its wide applications in electrical engineering. In this study, an attempt was made to overcome this limitation by adding carbon nanotubes (CNTs) into Al matrix using friction stir processing (FSP) method. The results showed that CNTs were singly distributed in Al matrix and strong bonded CNTs/Al interfaces without chemical reaction as well as impurity contamination were formed. Interestingly, it was found that the axis of CNTs tended to be parallel to Al (111) planes, which provided a geometric basis for the formation of semi-coherent CNTs/Al interfaces. These semi-coherent CNTs/Al interfaces possessed an extremely low electrical resistivity, which weakened the total electron scattering generated by all CNT/Al interfaces. Meanwhile, strong bonded CNTs/Al interfaces effectively hindered dislocations movement, inducing an improvement of 84 % and 50 % in yield strength and tensile strength of Al respectively. As a result, the strength of Al was significantly improved without losing its electrical conductivity. This study provides a new strategy for breaking through the contradiction between strength and electrical conductivity of Al and then producing CNTs/Al nanocomposites with high strength and high electrical conductivity.

The design of the electromagnetic aluminum mold of periodic action

This publication discusses a set of issues on computer modeling of electromagnetic and thermal processes in an induction crystallizer of an aluminum melt, in which forces are created between the melt and the inductor coil, compressing the column of liquid material and preventing direct contact of the melt with the crucible walls. In known induction systems using electromagnetic pressure on molten metal, for crystallization, the parameters of the inductor are selected so that, with sufficient force, the temperature does not rise due to internal sources of heat release with sufficient water cooling of the surface. In the proposed work, heat removal mainly occurs through contact with a water-cooled support surface. The aim of the work is to determine the process parameters at which the required electromagnetic force is formed on the melt wall, taking into account the change in the current density at the interface between the solid and liquid phases of aluminum. When determining the parameters of induction crystallizers, the temperature dependences of the thermophysical properties were used. Variants of the inductor realization are investigated, which makes it possible to cover the entire volume of the melt, inside which significant changes in the electrical conductivity of aluminum and the power of internal heat sources are observed. Obtaining a cylindrical shape of the ingot, in contrast to the known electromagnetic crystallizers, is achieved by determining the design of the inductor, which provides a decrease in the repulsive electromagnetic force acting on the side surface of the melt in height. The results of the study showed the possibility of using the crystallizer at various ratios of the height and diameter of the melt column, and the intensity of cooling. The efficiency of the process for aluminum increases with an increase in the radius of the melt column, which also leads to a decrease in shape distortion in the region of the upper end.

The Effect of a Small Copper Addition on the Electrical Conductivity of Aluminum

Adv. Eng. Mater. 2020, 22, 6, 2000058 In the above author byline, the author's name Chunjee Xu was misspelled. It should read: Chunjie Xu. The authors apologize for any inconvenience caused.

Corrosion of indium doped E-AlMgSi aluminum conductor alloy (Aldrey)

The effect of impurities on the electrical conductivity of aluminum has been studied in detail. The electrical conductivity of aluminum is 65.45% of that of copper. The tensile strength of aluminum wire is 150–170 MPa which, at equal conductivity, is about 65% of the strength of copper wire. This strength of aluminum wire is sufficient for bearing the wire’s own weight but may be too low in case of snow, ice or wind overloads. One way to improve the strength of aluminum wire is to use aluminum alloys having higher strength combined with sufficiently high electrical conductivity, e.g. the E-AlMgSi alloy (Aldrey). The key strengthening agent of the E-AlMgSi alloy (Aldrey) is the Mg2Si phase which imparts high mechanical strength to aluminum. In this work we present experimental data on the kinetics of high-temperature oxidation and electrochemical corrosion of indium doped E-AlMgSi aluminum conductor alloy (Aldrey). Thermal gravimetric study has shown that indium doping and high temperature exposure increase the oxidation rate of E-AlMgSi alloy (Aldrey), with the apparent alloy oxidation activation energy decreasing from 120.5 to 91.8 kJ/mole. Alloy oxidation rate data determined using a potentiostatic technique in NaCl electrolyte media have shown that the corrosion resistance of the indium doped alloy is 20–30% superior to that of the initial alloy. With an increase in NaCl electrolyte concentration the electrochemical potentials of the alloys decrease whereas the corrosion rate increases regardless of alloy composition.

The Effect of a Small Copper Addition on the Electrical Conductivity of Aluminum

Aluminum powder blended with 10, 20, and 30 wt% of copper powder is compacted at 400 °C by four reciprocal extrusion passes. Simultaneous compaction and strengthening result in more than double increase in mechanical strength characteristics for 20 and 30 wt% of copper and a significant increase in electrical conductivity for 30 wt% of copper. This phenomenon is investigated here by the expansion of the “effective media” model for a random binary mixture so that it includes the presence of intermetallic phases and considers the distribution of large copper agglomerates.

Simultaneously enhancing mechanical properties and electrical conductivity of aluminum by using graphene as the reinforcement

In this study, we demonstrated simultaneously enhanced mechanical properties and electrical conductivity of pure aluminum (Al) by incorporating graphene as the reinforcement. The graphene/Al nanocomposite was fabricated by friction stir processing (FSP) combined with hot extrusion. It was found that graphene was homogeneously dispersed into Al matrix and directly bonded graphene/Al interfaces were formed, which were the structure basis for the simultaneously improved electrical and mechanical properties. This study provides new strategy for fabricating high-strength and highly conductive graphene/Al nanocomposites.

Comparison of aerobic atrazine degradation with zero valent aluminum and zero valent iron

This study systematically compared the degradation of atrazine (ATR) with aerobic zero-valent aluminum (ZVAl/Air) and zero-valent iron (ZVI/Air) systems. By comparing the ATR degradation curves and rate in the ZVAl/Air and the ZVI/Air systems, a significant induction period was observed in the ZVAl/Air system, and the pseudo-first-order rate constant of ATR degradation in the second stage by ZVAl was 6.4 times faster than that by ZVI. The differences in ATR degradation patterns of the two systems stemmed from the different redox nature and electrical conductivity of aluminum (oxide) and iron (oxide). Reactive oxygen species measurement and electron spin spectra analysis indicated that more hydroxyl radical was generated through molecular oxygen activation in the ZVAl/Air system, leading to enhanced ATR degradation in the ZVAl/Air process. By analyzing the intermediates of atrazine degradation, we found that ATR underwent an oxidative dealkylation and hydroxyl-dechlorination degradation pathway, and the low toxicity cyanuric acid was the final product in both systems. However, aluminum ions released in the ZVAl/Air system exceeded the regulated standard value, which might cause environmental pollution. Finally, the pros and cons of potential environmental remediation of the ZVAl/Air and ZVI/Air processes were evaluated.

Thermodynamics and kinetics analyses of ZrB2 formation in molten aluminium alloys

Smelter grade aluminium can be used as a source for electrical conductor grade aluminium after the transition metal impurities such as zirconium (Zr), vanadium (V), titanium (Ti) and chromium (Cr) have been removed. Zirconium (Zr), in particular, has a significant effect on the electrical conductivity of aluminium. In practice, the transition metal impurities are removed by adding boron-containing substances into the melt in the casthouse. This step is called boron treatment. The work presented in this paper, which focuses on the thermodynamics and kinetics of Zr removal from molten Al–1 wt-%Zr–0.23 wt-%B alloy, is part of a broader systematic study on the removal of V, Ti, Cr and Zr from Al melt through boron treatment carried out by the authors. The thermodynamic analyses of Zr removal through the formation of ZrB2 were carried out in the temperature range of 675–900°C using the thermochemical package FactSage. It was predicted that ZrB2 is stable compared to Al–borides (AlB12, AlB2) hence would form during boron treatment of molten Al–Zr–B alloys. Al–Zr–B alloys were reacted at 750 ± 10°C for 60 minutes, and the change in the chemistry and microstructure were tracked and analysed at particular reaction times. The results showed that the reaction between Zr and AlB12/B was fast as revealed by the formation of boride ring at the early minutes of reaction. The presence of black phase (AlB12), i.e. the original source of B, after holding the melt for 60 minutes advocated that the reaction between Zr and AlB12/B was incomplete, hence still not reached the equilibrium state. The kinetics data suggested a higher reaction rate at the early minutes (2 minutes) of reaction compared to at a later stage (2–60 minutes). Nevertheless, a simple single-stage liquid mass transfer controlled kinetic model can be used to describe the overall process kinetic. The analysis of integrated rate law versus reaction time revealed that the mass transfer coefficient (km) of Zr in molten alloy is 9.5 × 10−4 m s−1, which is within a typical range (10−3 to 10−4 m s−1) observed in other metallurgical solid–liquid reactions. This study suggests that the overall kinetics of reaction was predominantly controlled by the mass transfer of Zr through the liquid aluminium phase.

Studying the Effect of Water on Electrical Conductivity of Carbon Reinforced Aluminum Composite Material

The aim of this study is to understand the effect of addition carbon types on aluminum electrical conductivity which used three fillers of carbon reinforced aluminum at different weight fractions. The experimental results showed that electrical conductivity of aluminum was decreased by the addition all carbon types, also at low weight fraction of carbon black; it reached (4.53S/cm), whereas it was appeared highly increasing for each carbon fiber and synthetic graphite. At (45%) weight fraction the electrical conductivity was decreased to (4.36Scm) and (4.27Scm) for each carbon fiber and synthetic graphite, respectively. While it was reached to maximum value with carbon black. Hybrid composites were investigated also; the results exhibit that minimum value of the electrical conductivity at combination of (45%) weight fraction of fillers, it was (3.49S/cm).The maximum value of electrical conductivity was recorded at 3.5% NaCl solution, it reached (8.82 S/cm) with (45% C. F) for 7 week.

Studying the Effect of Water on Electrical Conductivity of Carbon Reinforced Aluminum Composite Material

The aim of this study is to understand the effect of addition carbon types on aluminum electrical conductivity which used three fillers of carbon reinforced aluminum at different weight fractions. The experimental results showed that electrical conductivity of aluminum was decreased by the addition all carbon types, also at low weight fraction of carbon black; it reached (4.53S/cm), whereas it was appeared highly increasing for each carbon fiber and synthetic graphite. At (45%) weight fraction the electrical conductivity was decreased to (4.36Scm) and (4.27Scm) for each carbon fiber and synthetic graphite, respectively. While it was reached to maximum value with carbon black. Hybrid composites were investigated also; the results exhibit that minimum value of the electrical conductivity at combination of (45%) weight fraction of fillers, it was (3.49S/cm).The maximum value of electrical conductivity was recorded at 3.5% NaCl solution, it reached (8.82 S/cm) with (45% C. F) for 7 week.

Modification of aluminium and aluminium alloys by AL-B master alloy

Chemical compositions and microstructures affect on mechanical – physical and working properties of aluminium and aluminum alloys. Transition elements, such as Ti, V, Cr, Zr in solid solution greatly reduce the electrical conductivity of aluminium and its alloys. For reduction of detrimental effects of transition elements, Al-B master alloys are added into molten aluminium to occur reactions of boron and transition elements to form diborides of titanium, vanadium, chromium and zirconium, which are markedly insoluble in molten aluminium, then these transition elements have an insignificant effects on conductivity. In addition, Al-B master alloys is also used as a grain refiner of aluminium and aluminium alloys. Aluminium borides particles in Al-B master alloys act as substrates for heterogeneous nucleation of aluminium and its alloys. Al-B master alloys are prepared from low cost materials, such as boric acid H3BO3 and cryolite Na3AlF6, by simple melting method, easily realize in electrical wire and cable factories.

Preparation and Characterization of Aluminium Nanocomposites Based on MWCNT

Metal Matrix Composites (MMC) has wide range of engineering applications such as high strength, temperature, stiffness, yield strength and modulus of rigidity. Among the metals, aluminium is widely used due to its light weight. However, the electrical conductivity of aluminium is low when compared with copper. This paper deals with the development of aluminium nanocomposites based on Multi Walled Carbon Nanotubes (MWCNT) in order to enhance the electrical resistivity of aluminium. Morphology and electrical properties of the nanocomposites has been analyzed and compared with aluminium.

Thermal Stability of Aluminum Doped Zinc Oxide Thin Films

Transparent conductive oxides are key electrode materials for thin film solar cells. Aluminum doped zinc oxide has become one of the most promising transparent conductive oxide (TCO) materials because of its excellent optical and electrical properties. In this work, aluminum doped zinc oxide thin films were prepared using RF magnetron sputtering of a 4 at% ceramic target. The thermal stability of aluminum doped zinc oxide thin films was studied using various physical and structural characterization methods. It was observed that the electrical conductivity of aluminum doped zinc oxide thin films deteriorated rapidly and unevenly when it was heated up to 350 °C. When the aluminum doped zinc oxide thin films were exposed to UV ozone for a short time before heating up, its thermal stability and large area homogeneity were significantly improved. The present work provided a novel method for improving the durability of aluminum doped zinc oxides as transparent conductive electrodes in thin film solar cells.

A methodology for quantitative evaluation of local electrical conductivity: from micron to submicron

The local electrical conductivity of aluminum thin film with dimensions from micron to submicron was quantitatively measured by a four-point atomic force microscope (AFM) technique. The technique is a combination of the principles of four-point probe method and standard AFM. A silicon nitride based AFM probe with a V-shaped two-dimensional sliced structure tip was patterned by using conventional photolithography method. The probe was then etched to four parallel electrodes isolated from each other, for the purpose of performing current input and electrical potential drop measurement. The spacing between electrodes is smaller than 1.0 μm, which facilitates the quantitative electrical conductivity measurement of ultrathin film. The four-point AFM probe technique is capable of measuring surface topography together with local conductivity simultaneously. The technique was applied to a series of 99.999% aluminum thin films with thicknesses from micron to submicron. The repeatable measurements demonstrate the capability of this technique and its possible extension to be used for fast in situ electrical properties characterization of submicron interconnects that widely applied in nanosensors and nanodevices.

Calculation of the Electrical Conductivity of Liquid Aluminum, Copper, and Molybdenum

The electrical conductivity of aluminum, copper, and molybdenum is calculated using the Ziman theory of liquid metals and modified Ashcroft potential. The Ashcroft potential is modified so as to take into account the change in the ion charge during transitions from liquid to hypercritical phase. The results of this study are compared to the results of calculations and experiments performed by other authors.

Complex investigation of the thermal and electrophysical properties of refractory oxides in the liquid and solid phases

Results of an experimental investigation of the enthalpy and specific electrical conductivity of aluminum and scandium oxides in the 1570–3100°K range and also of the heats of fusion of these oxides are presented.

Conductivite electrique des magnetites faiblement substituees a l'aluminium ou au chrome et faiblement oxydees au voisinage de la temperature de transition de Verwey

The electrical conductivity of aluminum or chromium slightly substituted and slightly oxidized magnetites (0 < x < 0.27; 0 < δ 0.040) whose formula is Fe 3+[□ δFe (1−3δ) 2+Fe (1− x ) + 28 3+M x 3+]O 4 2− over the temperature range 300-77°K is affected by the composition of octahedral sites. In particular the Verwey transition temperature and its magnitude decrease with x and δ while the electrical conductivity and activation energy evolve differently on either side of this discontinuity.

Electrical conductivity of aluminum and titanium base reinforced composites

1. For aluminum reinforced with steel fibers, increasing the fiber concentration to 50–60 vol. % produces only a small increase in the electrical resistivity of the composite. At higher fiber concentrations the rate of ascent of theϱ vs Vf curve sharply increases. 2. For titanium base composites reinforced with molybdenum fibers, at low reinforcing phase contents (of the order of 10–20 vol.%) the electrical resistivity of the composites decreases by a factor of more than 2 to 3 compared with the resistivity of the matrix. Subsequently, the rate of fall ofϱ slows down. 3. The experimental curves of resistivity vs composition and temperature for all the composites investigated are similar in character to the curves obtained analytically; however, the experimental values are slightly higher than the calculated results, by 3–4% for the aluminum base composites and by 10–12% for the titanium base composites.

Equilibrium Vacancies and Electrical Conductivity of Aluminium

Equilibrium Vacancies and Electrical Conductivity of Aluminium

Influence of small amounts of cerium, iron, nickel, and cobalt on the mechanical properties and electrical conductivity of aluminum

1. Cerium (0.1 and 0.5%) together with iron (or Co) increases the strength and the corrosion resistance of aluminum conductors without altering their ductility. The resistivity increases very little. 2. A small amount of cerium together with nickel increases the strength insignificantly but considerably decreases the corrosion resistance of aluminum.