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This paper focuses on preparation of Al–Zr master alloy and Al3Zr intermetallic compound. A method is proposed to obtain Al3Zr intermetallic compound from Al–Zr master alloy by leaching. The alloy was prepared by electrolysis in 2.4NaF–AlF3–5 wt % CaF2–5 wt % ZrO2 cryolite-based electrolyte with the molten Al as cathode and the high purity graphite as anode at 980°C. Zirconium was deposited in the form of solid Al3Zr at the bottom of the cathode alloy, and the main phase compositions of the obtained Al-base alloy product were Al phase and Al3Zr phase. Then, cube-shaped Al3Zr intermetallic compound particles with an average size of 37.8 μm were obtained from the Al–Zr master alloy product by combining alkaline and acidic leaching. [ABSTRACT FROM AUTHOR]

Zinc is a commonly used corrosion-resistant coating for steel surface protection. In this study, the ethylene carbonate-zinc chloride (EC-ZnCl2) electrolyte systems are selected for zinc electrodeposition, and their ionic structure and properties were studied. The corrosion resistance of the electrodeposited zinc coatings obtained from 4EC-ZnCl2, 3EC-ZnCl2, and 2EC-ZnCl2 systems was analyzed. Raman spectroscopic analysis shows that these EC-ZnCl2 systems contain [Zn2Cl6]2− species. The relationship between conductivity, viscosity, and density with the temperature of EC-ZnCl2 systems was provided. Scanning electron microscopy (SEM) and potentiodynamic polarization curve (Tafel) tests showed that when the deposition was carried out at –1.0 V and –1.2 V (vs. Ag/AgCl) for two hours, a uniform zinc coating with good corrosion resistance could be obtained. [ABSTRACT FROM AUTHOR]

Extracting aluminum from aluminum alloys in AlCl3-NaCl molten salts was investigated in this paper. The influences of experimental parameters such as electrolyte composition, cathodic current density and electrolysis time on the deposits morphology were discussed. The results show that the grain size of the deposits decreases with the increase of AlCl3 content in the electrolyte. Current density has a big effect on the morphology of the deposits. The particle size of deposits increases with the increase of current density, and dendritic morphology forms at high current density. High nucleation rates are achieved at high current densities above the limiting diffusion current density, and will result in a finer grain size. A non-dendritic deposit of aluminum was obtained at 170°C at 50 mA cm−2 cathodic current density for 1 h in the electrolyte having a 1.3 molar ratio of AlCl3/NaCl. The purity of the aluminum deposit is about 99.79% analyzed using inductively coupled plasma.

The decomposition mechanism of K3AlF6 was investigated by quantum chemical calculation based on density functional theory (DFT). In order to clarify the structure properties of the optimized K3AlF6, the Mayer bond order (MBO) was systematically calculated. Two dissociation paths of K3AlF6 were determined, meanwhile, trigonal bipyramidal and tetragonal pyramidal structures of [AlF5]2– complex ions were verified during the decomposition of K3AlF6. Furthermore, based on the data of calculated rate constants within a temperature range of 498–1473 K at canonical variational theory (CVT), it was thought that the decomposition reaction R1 involving Al2-F4/F7/F8 bond ruptures contributed much more to the decomposition of K3AlF6. Moreover, the calculated Raman spectrum of [AlF5]2– was close to the experimental spectrum. According to the analysis on the decomposition mechanism of K3AlF6 and theoretical Raman spectra, the trigonal bipyramidal structure of [AlF5]2– complex has been proved to be the main product in the dissociation reaction of K3AlF6. [ABSTRACT FROM AUTHOR]

The oxidation behavior of Fe-Ni alloys containing 10, 20, 43, 50, 57 and 80 (mass%) nickel was studied over the range 700°C–950°C in laboratory air atmosphere using thermogravimetric, XRD and SEM/EDAX techniques. The results showed that some oxidation kinetic curves of Fe-Ni alloys follow the parabolic law, some follow a cubic law, while the oxidation kinetic curves of 90Fe-10Ni is linear. XRD and SEM/EDAX results showed that the oxide scale consists of an outer layer of Fe2O3 and an inner layer of Ni-Fe-O and NiO compound. Ni content in the alloy has an important role for the formation of NiFe2O4 oxide. 20Fe-80Ni and 43Fe-57Ni can form NiFe2O4 at 700°C–950°C, while 50Fe-50Ni can form NiFe2O4 only oxidized at higher temperature of 950°C.

Fe-Ni-Al2O3 cermet materials were prepared, and the electrolysis with these anodes were performed in cryolite-based electrolyte consisted of 44NaF-40AlF3-8NaCl-5CaF2-3Al2O3(wt%) at 850 °C. The purity of produced aluminium is 97–98%, while the calculated anodic corrosion rate is 18.2 mm/a–24.0 mm/a. The EPMA analysis showed that there is an oxide scale consisting of Fe2O3 and FeAl2O4 on the anode working surface. The homeostasis of dissolution and formation of oxide scale makes the thickness of the oxide scale and the cell voltage stable within a certain range. The dissolution of oxide scale results in the presence of FeF3 in the electrolyte. By analysis of the corrosion process, it shows that low temperature, high alumina concentration and low CR electrolysis is preferred for using Fe-Ni-Al2O3 inert anodes for aluminium electrolysis.