De-Bin Ji

AlCl3 and liquid Al assisted extraction of Nd from NaCl–KCl melts via intermittent galvanostatic electrolysis

The electrochemical reduction of Nd(III) was investigated on an inert W and a liquid Al electrode in molten NaCl–KCl eutectic salt. On both W and liquid Al electrodes, the reduction of Nd(III) ions to Nd(0) metal occurred in a single reaction step, which avoids the corrosion reaction: 2Nd(III) + Nd → 3Nd(II). Therefore, corrosion of Nd metal in this molten chloride media is not expected. The co-reduction behavior of Nd(III) and Al(III) ions was studied on a W electrode in NaCl–KCl–AlCl3–NdCl3 melts. Five kinds of Al–Nd intermetallic compound were detected via cyclic voltammetry and open circuit chronopotentiometry. Intermittent galvanostatic electrolysis was employed on liquid Al electrodes to extract Nd in the form of Al–Nd alloys in NaCl–KCl–NdCl3 melts. Nd, AlNd3, Al2Nd, and AlNd phases were identified by X-ray diffraction (XRD). With the increase of electrolytic time, the content of Nd-rich Al–Nd intermetallic compounds in the Al–Nd alloy increased. The morphology and micro-zone chemical analysis of the deposits were characterized by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), and the Al11Nd3 phase was confirmed by EDS analysis.

Electrochemical reduction La(III) on W and Mg electrodes: application to prepare Mg–La and Mg–Li–La alloys in LiCl–KCl melts

The electrochemical behavior of La(III) ions was studied by different electrochemical measurements in LiCl–KCl–MgCl2 melts on a W electrode and in LiCl–KCl melts on an active Mg electrode at 873 K, respectively. Both on the W and Mg electrodes, three kinds of electrochemical signals corresponding to the formation/dissolution of Mg–La intermetallic compounds (Mg17La2, Mg3La and MgLa) were observed. Chronopotentiometry illustrated that, on the W electrode, the co-deposition of Mg(II), Li(I) and La(III) ions will be realized when the current density is more than −0.776 A cm−2. Potentiostatic electrolysis was employed to prepare Mg–La alloys on active magnesium electrodes, and galvanostatic electrolysis was carried out to synthesize Mg–Li–La alloys on the W electrodes. The phase composition, microstructure and micro-zone chemical analysis of the alloys were analyzed by XRD and SEM equipped with EDS analysis, respectively. The XRD patterns and SEM analysis indicate that the phase composition and alloy film thickness of Mg–La alloys can be regulated by the electrolytic potentials. The phase composition and crystalline structure of the Mg–Li–La alloys can be adjusted by adjusting the concentrations of MgCl2.

Study on formation and properties of Al–Li–Sm alloy containing whiskers in molten salts

The electrochemical behaviors of samarium ions on a liquid aluminum electrode in LiCl–KCl melts at 973 K were investigated by cyclic voltammetry, square wave voltammetry and a cathodic polarization test. The results show that only one kind of Al–Sm intermetallic compound can be formed under our experimental conditions. The Al–Li–Sm alloy containing whiskers was obtained by galvanostatic electrolysis in LiCl–KCl melts after the addition of 10 wt% SmCl3 on a liquid aluminum electrode at 973 K. The alloy containing whiskers was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS). Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to examine the percentage composition of each element. Transmission electron microscopy (TEM) with electron diffraction was employed to characterize the crystal structure of the needle-like precipitates. The mechanical properties of the micro hardness and Young’s modulus were characterized by the Leitz micro hardness tester and the tool for Young’s modulus, respectively.

Electrochemistry of Zn and co-reduction of Zn and Sm from LiCl–KCl melt

The electrochemical behavior of Zn(II) ions in LiCl–KCl and Sm(III) ions in LiCl–KCl–ZnCl2 melts on a Mo electrode at 773 K was studied by various electrochemical techniques. The results showed that the reduction of Zn(II) to Zn(0) consisted of a one-step process. The electrode reaction of LiCl–KCl–ZnCl2 solutions indicated that the under potential deposition of Sm on pre-deposited Zn electrode formed three kinds of Zn–Sm intermetallic compounds at electrode potentials around −1.57, −2.17 and −2.29 V. The electrochemical extraction of samarium was carried out in LiCl–KCl–ZnCl2 melts on a Mo electrode at 773 K by potentiostatic electrolysis (−2.3 V) for 40 h with an extraction efficiency of 99.87%. Zn–Sm bulk alloy was obtained by galvanostatic electrolysis. The microstructure and micro-zone chemical analysis of the Zn–Sm alloy were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS).