Electrochemical Preparation of ZrFe₂ and ZrFe_1.8Ni_0.2 Intermetallic Compounds by FFC Cambridge Process

Abstract

The aim of the present study was to prepare ZrFe2 and ZrFe1.8Ni0.2 intermetallic compounds by FFC Cambridge process. The intermetallic compounds were prepared directly from the mixed oxide precursors, namely ZrO2-Fe2O3 and ZrO2-Fe2O3-NiO, respectively. Electrochemical de-oxidation experiments were carried out with mixed oxide pellet cathode and HD graphite anode by applying a constant cell voltage of 3.1 V in CaCl2 melt at 900 oC. The electrochemical behaviour of oxides was studied by cyclic voltammetry using metallic cavity electrodes (MCEs). The electrolysis was carried out for different durations of time to understand the mechanistic pathway of reduction of ZrO2-Fe2O3. The electro-reduced products were characterized by X-ray diffraction (XRD) technique, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The reduction intermediates involved Fe, CaZrO3, calcia stabilised zirconia (CSZ), Fe23Zr6, Zr6Fe3O and Zr2Fe. Single cubic C15 phase of ZrFe2 was obtained in 48 h electrolysis product. ZrFe1.8Ni0.2 was also electrochemically synthesized from its oxide precursors viz. ZrO2, Fe2O3 and NiO. Apart from ZrFe1.8Ni0.2 phase, the electro-reduced products had a Zr2Ni phase even after 72 h of electrolysis.

Electrochemical Preparation of Ti2CrV Alloy in CaCl2 Melt

“…The obtained cyclic voltammogram (not shown) was similar to our previous studies. 19 The calcium deposition and chlorine evolution onset potentials were observed at −2.25 V (vs Ni|NiO) and +0.98 V (vs Ni|NiO), respectively. There were no additional distinct current signatures apart from the calcium deposition and chlorine evolution, which indicated that the melt was free from redox-active impurities.…”

“…10,11 The FFC Cambridge process has also been used for the preparation of various alloys and intermetallics, including hydrogen storage alloys (HSAs) such as TiFe, TiFe 0.4 Ni 0.6 , ZrCr 2 , ZrCr 0.7 Ni 0.3 , ZrMn 2 , ZrFe 2 , ZrFe 1.8 Ni 0.2 , LaNi 5 , La 0.5 Ce 0.5 Ni 5 , LaNi 4 Co, CeNi 5 , and TbNi 5 , from the mixed metal oxides. 9,[12][13][14][15][16][17][18][19][20][21] The main advantage of the FFC Cambridge process over the conventional arc-melting process is that it offers a more economical, feasible, and energy-efficient route for the preparation of these alloys and intermetallics. 22,23 In the FFC Cambridge process, a constant cell voltage is applied between a solid metal oxide cathode and a graphite anode, which results in the deoxidation of metal oxide.…”