1. Preparation and electrochemical characterization of aluminium liquid battery cells with two different electrolytes ($NaCl-BaCl_2-AlF_3-NaF$ and $LiF-AlF_3-BaF_2$)Viktor Napast, Jože Moškon, Marko Homšak, Aljana Petek, Miran Gaberšček, 2015, original scientific article Abstract: The possibility of preparation of operating rechargeable liquid battery cells based on aluminium and its alloys is systematically checked. In all cases we started from aluminium as the negative electrode whereas as the positive electrode three different metals were tested: $Pb$, $Bi$, and $Sn$. Two types of electrolytes were selected: $Na_3AlF_6-AlF_3-BaCl_2-NaCl$ and $Li_3AlF_3-BaF_2$. We show that some of these combinations allowed efficient separation of individual liquid layers. The cells exhibited expected voltages, relatively high current densities and could be charged and discharged several times. The capacities were relatively low (120 mAh in the case of $Al-Pb$ system), mostly due to unoptimised cell construction. Improvements in various directions are possible, especially by hermetically sealing the cells thus preventing salt evaporation. Similarly, solubility of aluminium in alloys can be increased by optimising the composition of positive electrode.
Keywords: liquid batteries, aluminium, alloy, electrochemistry
Published: 24.08.2017; Views: 628; Downloads: 264
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2. The action of a laser on an aluminium targetVišnja Henč-Bartolič, Tonica Bončina, Suzana Jakovljević, Davor Pipić, Franc Zupanič, 2008, original scientific article Abstract: A nitrogen laser beam (337 nm, 6 ns (FWHM), (3.2 [plus minus] 0.2) mJ) was focused with a quartz lens (f = 100 mm) onto an aluminium target in air at normal pressure. The laser irradiation and plasma explosion caused a modification to the Al surface and the deposition of a thin film (droplets) onto a glassy carbon plate. The irradiated target and the deposited material were studied with a scanning electron microscope (SEM) and a focused-ion-beam (FIB) device. A crater surrounded by a rim was produced on the spot of maximum irradiation on the aluminium target. The crater, very deep in comparison to its width and thickness, was presumably caused by the Kelvin-Helmholtz and the Rayleigh-Taylor instabilities. The temperatures of the electron and the massive particles were explained.
Keywords: aluminium, laser ablation, thin film deposition, instabilities, temperatures
Published: 23.03.2017; Views: 667; Downloads: 74
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3. DSC/TG of Al-based alloyed powders for p/m applicationsBorivoj Šuštaršič, Jože Medved, Srečko Glodež, Marko Šori, Albert Korošec, 2014, original scientific article Abstract: Al-based alloyed powders, appropriate for the sintering procedure (powder metallurgy, P/M) contain the alloying elements with a high solid solubility in Al, enabling reaction and liquid-phase sintering. They are surface oxidised because of a high affinity of Al to oxygen. Besides, this type of powders contains a polymeric lubricant (wax), which reduces the friction on die walls during automatic die compaction into the final compact shape of a product. This lubricant has to be removed slowly during the first stage of sintering in order to prevent deformations and cracking of the product. Consequently, its sintering is very complex. Generally, these powders are sintered in pure nitrogen with a low dew point. The optimum sintering conditions are generally determined on the basis of light and scanning electron microscopy. The investigation can also be completed very successively with differential scanning calorimetry and thermo gravimetry. The first one allows an insight into the endo- and exothermic reactions, taking place during the heating and cooling of a compacted metal powder, and the second one allows an insight into the processes, connected with the mass loss (a reduction, a lubricant removal, etc.) or mass increase (an oxidation). The DSC/TG of three commercial Al-based alloyed powders was performed in the frame of our investigations. The results were compared with the theoretical thermodynamic-based calculations and the optimum sintering conditions were proposed.
Keywords: aluminium powders, sintering, differential scanning calorimetry and thermo gravimetry
Published: 15.03.2017; Views: 644; Downloads: 71
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4. Challenges and advantages of recycling wrought aluminium alloys from lower grades of metallurgically clean scrapVaružan Kevorkijan, 2013, review article Abstract: In the recycling of wrought aluminium alloys from lower grades of scrap (metallurgically clean but highly contaminated with non-metallic impurities) the following two tasks were identified as the most demanding: (i) achieving the required final chemical composition of an alloy with a minimal addition of primary aluminium and alloying elements; and (ii) keeping the level of impurities (inclusions, hydrogen, trace elements and alkali metals) in the molten metal below the critical level. Because of the lack of chemically based refining processes for reducing the concentration of alloying and trace elements in the molten aluminium, once the concentrations of these constituents in the melt exceed the corresponding concentration limits, the only practical solution for their reduction would be an appropriate dilution with primary metal. To avoid such a costly correction, carefully predicting and ensuring the chemical composition of the batch in the pre-melting stage of casting should be applied. Fortunately, some of the impurities, like hydrogen and alkali metals, as well as various (mostly exogeneous) inclusions, could be successfully reduced by employing existing refining procedures. In this work, (i) the state-of-the-art technologies, including some emerging technical topics such as the evolution of wrought alloys toward scrap-intensive compositions, monitoring of the content of organics in the incoming scrap and the quality of molten metal achieved by different smelting and refining technologies, and (ii) the relevant economic advantages of the recycling of wrought aluminium alloys from the lower grades of scrap are reported. By analyzing the market prices of various grades of scrap and the total cost of their recycling, the cost of aluminium ingots made from recycled aluminium was modelled as a function of aluminium and the alloying-element content in the incoming scrap. Furthermore, scrap mixtures for producing aluminium wrought alloys of standard quality from lower grades of scrap and with a significant new added value were illustrated.
Keywords: wrought aluminium alloys, recycling, low grades of aluminium scrap, quality of recycled metal, economic benefits
Published: 21.12.2015; Views: 1015; Downloads: 29
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5. The influence of cooling rate on the microstructure of an Al-Mn-Be alloyNiko Rozman, Tonica Bončina, Ivan Anžel, Franc Zupanič, 2008, original scientific article Abstract: In ternary Al-Mn-Be alloys a metastable quasicrystalline phase can form at relatively low cooling rates (≈ 100 K/s); however, besides the quasicrystalline phase other phases can also be present. We found that the investigated alloy is very prone to the formation of metastable phases, which are also quasicrystalline. Using different investigation methods we determined the type of phases, their shape, morphology, chemical composition and distribution. Special attention was given to the micro- and nano-sized quasicrystalline particles. When using slow cooling, Al10Mn3 and Be4AlMn were present; however, with a faster cooling rate a quasicrystal approximant and a quasicrystalline phase were formed.
Keywords: aluminium, quasicrystals, cooling rate, microstructure
Published: 10.07.2015; Views: 867; Downloads: 50
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7. Dynamic property of aluminium foamSeiichi Irie, Toshihiko Okano, Shigeru Tanaka, Matej Vesenjak, Zoran Ren, Kazuyuki Hokamoto, Shigeru Itoh, 2010, published scientific conference contribution abstract Keywords: aluminium foam, powder gun, high strain rate
Published: 10.07.2015; Views: 936; Downloads: 30
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