Xueliang Xie

Reductive kinetics of Panzhihua ilmenite with hydrogen

Abstract The hydrogen reduction of Panzhihua ilmenite concentrate in the temperature range of 900–1050 °C was systematically investigated by thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. It was shown that the products of the Panzhihua ilmenite reduced at 900 °C were metallic iron and rutile. Above 1000 °C, ferrous pseudobrookite solid solution was generated. During the reduction process, element Mg gradually concentrated to form Mg-rich zone which can influence the metallization process. The reduction reaction proceeded topochemically and its related reduction kinetics were also discussed. The kinetics of the reduction indicated that the rate-controlling step was the diffusion process. The apparent activation energy of the hydrogen reduction of Panzhihua ilmenite was calculated to be 117.56 kJ/mol, which was larger than that of synthetic ilmenite under the same reduction condition.

Electrochemical Fabrication of Micro/Nanoporous Copper by Electrosynthesis-Dealloying of Cu–Zn Alloy in Deep Eutectic Solvent

The electrodeposition of Cu–Zn alloy films on a Ni substrate from CuO and ZnO precursors in choline chloride (ChCl)/urea (1:2 molar ratio) based deep eutectic solvent (DES) was firstly carried out. Then, micro/nanoporous Cu films were fabricated by further electro-dealloying of the synthesized Cu–Zn alloy films. XRD analysis indicates that the phase compositions of the deposited Cu–Zn alloys are Cu5Zn8 and CuZn5. Further investigation shows that the more-active component Zn would be dissolved during the electro-dealloying process, and porous Cu can be obtained. The result reveals that the electrosynthesis-dealloying process may provide a promising strategy for the production of micro/nanoporous Cu at low temperature.

Electrodeposition of Zn, Cu, and Zn-Cu Alloys from Deep Eutectic Solvents

Deep eutectic solvents (DESs) comprising choline chloride (ChCl) with either urea or ethylene glycol (EG) have been successfully used as powerful and potential electrolytes for extracting metals from their corresponding metal oxide precursors. In this work, for electrodeposition of Zn and Zn-Cu alloys, ChCl/urea-based DES was employed. Cyclic voltammetry study demonstrates that the reduction of Zn(II) to Zn is a diffusioncontrolled quasi-reversible, one-step, two electrons transfer process. Micro-/nanostructured Zn and Zn-Cu alloys films have been electrodeposited directly from their metal oxide precursors in DES, and the Zn and Zn-Cu alloy films exhibit homogeneous morphologies with controlled particle sizes. Besides, the electrodeposition of Cu from CuO in the eutectics based on ChCl with urea and EG has been investigated, respectively. The higher coordinated Cu species in the ChCl/urea-based DES are obviously more difficult to reduce, and higher overpotential is needed to drive the nucleation process compared with the lower coordinated Cu species in the ChCl/EG-based DES. The surface morphology of the Cu electrodeposits is significantly affected by the type of DES and the electrodeposition potentials. Furthermore, the Cu electrodeposits obtained in the ChCl/urea-based DES possess more dense microstructures than those produced in the ChCl/EG-based DES.

Corrosion Mechanism of MgO‐C Ladle Refractory in Contact with MgO‐CaO‐Al2O3‐SiO2 SLAG

The corrosion resistance and corroded microstructure of MgO-C refractory in molten slag are investigated by immersion test in muffle furnace at 1600 °C. The microstructure and chemical compositions of the specimens after erosion experiment are characterized by scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The results confirm that the oxidation of graphite is the most important degradation mode of MgO-C refractory. The structure of the refractory material is damaged due to the decrease of graphite, as a result, the periclase substrate reacts with the molten slag directly. The corrosion process is controlled by the dissolution of the refractory materials into slag, low melting point oxides are therefore generated which lead to the damage of MgO-C refractory finally.