Aluminum — a metal whose scope of application is constantly expanding. At present, aluminum and its alloys in a number of areas successfully displace traditionally used metals and alloys. The widespread use of aluminum and its alloys is due to its properties, among which, first of all, low density, satisfactory corrosion resistance and electrical conductivity, ability to apply protective and decorative coatings should be mentioned. All this, combined with the large reserves of aluminum in the earth’s crust, makes the production and consumption of aluminum very promising. One of the promising areas for the use of aluminum is the electrical industry. Conductive aluminum alloys type E-AlMgSi (Aldrey) are representatives of this group of alloys.One of the promising areas for the use of aluminum is the electrical industry. Conducting aluminum alloys of the E-AlMgSi type (Aldrey) are representatives of this group of alloys. The paper presents the results of a study of the temperature dependence of heat capacity, heat transfer coefficient, and thermodynamic functions of an aluminum alloy E-AlMgSi (Aldrey) with gallium. Research conducted in the “cooling” mode. It is shown that the temperature capacity and thermodynamic functions of the E-AlMgSi alloy (Aldrey) with gallium increase, while the Gibbs energy decreases. Gallium additives up to 1 wt.% Reduce the heat capacity, enthalpy, and entropy of the initial alloy and increase the Gibbs energy.
Экономическая целесообразность применения алюминия в качестве проводникового материала объясняется благоприятным соотношением его стоимости (которая в течение многих лет практически не меняется) и стоимости меди. При использовании проводниковых алюминиевых сплавов для изготовления тонкой проволоки, обмоточного провода и др. могут возникнуть определенные сложности в связи с их недостаточной прочностью и малым числом перегибов до разрушения. В последние годы разработаны алюминиевые сплавы, которые даже в мягком состоянии обладают прочностными характеристиками, позволяющими применять их в качестве проводникового материала. Одним из перспективных потребителей алюминия является электротехническая промышленность. Отсюда разработка новых составов сплавов на основе этого металла весьма актуальна. Экспериментально определена температурная зависимость теплоемкости сплавов алюминия марки А7Е с медью и выполнен расчет изменений их термодинамических функций. Исследования проводились в режиме охлаждения с применением компьютерной техники и программы «Sigma Plot». Установлены полиномы температурной зависимости теплоемкости и изменения термодинамических функций (энтальпии, энтропии и энергии Гиббса) указанных сплавов и эталона (Al марки A5N), характеризуемые коэффициентом корреляции R корр = 0,992÷0,998. Показано, что с ростом содержания меди теплоемкость сплавов алюминия марки А7Е снижается, а с увеличением температуры повышается. Энтальпия и энтропия сплавов алюминия марки А7 с медью с увеличением доли меди уменьшаются, а с ростом температуры повышаются. Для энергии Гиббса характерна обратная зависимость.
The purpose of this work was to find out the features of oxidation of the aluminum alloy АЖ2.4М5.3Мг1.1Ц4Кр3 doped with tin and to develop new alloy compositions with improved characteristics. The thermogravimetric method was used to determine the oxidation kinetics of the aluminum alloy АЖ2.4М5.3Мг1.1Ц4Кр3, containing up to 0.5 wt% tin. The results showed that the process of weight gain of alloys during first 15-20 minutes of oxidation grows intensively, and then acquires an almost constant value. Oxide films formed at the beginning of the oxidation process did not possess protective properties, that fact explains an increase in the rate of oxidation of alloys with temperature in the first period. An increase in the rate of oxidation of alloy samples with temperature is noted. As well, the results revealed that tin at concentrations of 0.01 - 0.5 wt.% reduces the oxidability of the initial alloy, which is accompanied by an increase in the apparent activation energy from 82.1 to 104.3 kJ/mol.
Aluminum is a metal having permanently broadening applications. Currently aluminum and its alloys successfully replace conventional metals and alloys in a number of application fields. The wide use of aluminum and its alloys is primarily stipulated by its advantageous properties e.g. low density, high corrosion resistance and electrical conductivity as well as the possibility of applying protective and decorative coatings. In combination with great abundance and relatively low cost which has been almost constant in recent years, this permanently broadens the application range of aluminum. The electrochemical industry is one of the promising application fields of aluminum. The E-AlMgSi type (Aldrey) conductor aluminum alloy has high strength and ductility. This alloy acquires high electrical conductivity upon appropriate heat treatment. Products made from it are used almost exclusively for overhead power lines. This work presents data on the temperature dependence of heat capacity, heat conductivity and thermodynamic functions of the E-AlMgSi (Aldrey) aluminum alloy doped with gallium. The studies have been carried out in "cooling" mode. It has been shown that with an increase in temperature the heat capacity and thermodynamic functions of E-AlMgSi (Aldrey) alloy doped with gallium increase while the Gibbs energy decreases. Gallium doping to 1 wt.% reduces the heat capacity, enthalpy and entropy of the initial alloy and increases the Gibbs energy.
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.
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