Shenggang Zhou

Calculation of Liquid–Solid Interfacial Free Energy in Pb–Cu Binary Immiscible System

Abstract Based on the solid–liquid interfacial free energy theory of the complex Warren binary & pseudo-binary system and through the simplification of it by taking Pb–Cu binary system as an example, the physical model for it in binary immiscible system can be obtained. Next, its thermodynamic formula is derived to obtain a theoretical formula that only contains two parameters, and comparisons are made with regard to γSL calculated values and experimental values of MPE (multiphase equilibrium method) under several kinds of temperatures. As manifested in the outcomes, the improved physical model and theoretical formula will become not only easy to understand but also simple for calculation (the calculated value of γSL depends on two parameters, i.e. temperature and percentage composition of Cu atom). It can be treated as the foundation of application for the γSL calculation of liquid–solid interfacial free energy in other immiscible systems.

Site preferences and effects of X (X = Mn, Fe, Co, Cu) on the properties of NiAl: A first-principles study

The site preference of X (X = Mn, Fe, Co, Cu) in NiAl and its effects on structural, electronic and elastic properties were investigated by performing first-principles calculations using density functional theory (DFT). Formation enthalpy calculations show that adding X increases the formation enthalpy of NiAl, indicating that X addition reduces the stability of system. The site preference was investigated by calculating the transfer energy of NiAl alloys with X. The results further exhibit that Mn, Fe and Cu show no site preference, but Co tends to occupy Ni site. By analyzing electronic density of states, Mulliken population, overlap population and valence charge density, the electronic property and bond characters were discussed. The elastic property calculation shows that only substitution of Ni by Cu increased the plasticity of alloy, while in the other cases the plasticity was decreased.

Electrocatalytic Properties of RuO2-TiO2 and TiB2 Coated Ti Based Anodes

Ti-based anodes with a top layer RuO2-TiO2 oxides mixture and an inter-layer TiB2 were prepared by two step processes, i.e. first the TiB2 film was deposited on Ti-based anodes by means of magnetron sputtering and then the top layer RuO2-TiO2 oxides mixture was further deposited by a thermal decomposition process. The microstructure and phase constituent of the coatings were characterized by means of SEM and XRD, and the electrochemical properties of the anodes were evaluated by the polarization curves. The results show that the interlayer TiB2 plays important role in suppressing the formation of the cross cracks of the RuO2-TiO2 layer and, facilitating the adhesion of the top layer to the substrate,therefore the RuO2-TiO2 and TiB2coated Ti-anodes exhibit better electrocatalytic properties rather than the only RuO2-TiO2 coated ones. In the meanwhile, the TiB2 interlayer can suppress the occurrence of a TiO2 film at the interface coating/substrate thus prolongs the life time of Ti-anodes. Besides, the inducing of the TiB2 interlayer can reduce the potential of chlorine evolution, and thereby enhance the current efficiency of the Ti-anodes effectively.

The Study of Ti-Al Layered Composite Electrode in the Anti-Gravity Casting Method

The structure and properties of the Ti-Al composite electrode materials prepared by the anti-gravity casting method was analyzed by SEM, EDS, four-probe method and electrochemical workstation. The results show that the metallurgical bonding of Ti and Al can be achieved by the method of anti-gravity casting with the Al temperature800°C, mold temperature of 400°C, pressure difference 0.5MPa. The electrochemical properties of the composite electrode materials is much better than pure Ti anode. Under the same condition,polarization potential of composite materials will fell by 32mV~43mV in polarization potential of pure Ti, it can be increased by 60% or more in current density, the resistivity was only 1/10 of pure Ti.

First-Principles Calculation of Intermetallics on Novel Anode Materials

Our team proposes the design concept of layered composite electrode materials. Change the single substrate of traditional electrode material by using thermal pressing diffusion welding to synthesize sandwich structure electrode substrate of titanium cladding aluminum. Only Al3Ti phase is obtained in the composite interface. First-principles calculations have been used to calculate the formation enthalpy and binding energies, and the respective order of their value are as follows: AlTi3<AlTi<Al2Ti<Al3Ti,AlTi3<AlTi<Al2Ti<Al3Ti. AlTi3 near Fermi surface is zero and it has good conductivity. It has the strongest bonding capability and stability. Practical application of this new anode in the field of hydrometallurgy has good conductivity, strong adaptability.

Application of ANSYS in Electric Field Distribution of Ti-Al Layered Composite Materials

This paper changed the matrix structure model of traditional electrode materials from the the composition of the internal structure of the matrix, used solid-solid compound method of hot pressing diffusion welding for sandwich type structure Ti-Al layered composite materials, The Ti/IrO2-Ta2O5 were got by typical oxygen evolution model coating ingredient(mole ratio of Ir to Ta was 7:3). Microstructure of the layered composite materials was studied by scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS), and then the current distribution performance as the anode material for nickel electrowinning in NiSO4-H2SO4 system was characterized by electric analysis module of ANSYS program . The results showed that, The findings indicate that the interface formation of Ti-Al layered composite materials was a reaction-diffusion process. In the technology conditions of this subject, the phase of interface was Al3Ti. Compared with the traditional DSA (Dimensionally Stable Anode) titanium anode, the Ti-Al layered composite anode showed a more uniform current distribution performance.

Characterisation of Ti-Al and Ti-Cu Laminated Composite Electrode Materials

We proposed using Ti-Al and Ti-Cu laminated composites instead of single Ti electrode metals, as well as studied the difference in performance between laminated composite electrode materials and pure-Ti electrode. The analysis of the conductivity and electrochemical performance of electrode matrix material indicates the result that the improvement of matrix material by using Ti-Al and Ti-Cu laminated composites, better performance for conductivity of electrode, and be beneficial to homogenize the electrode surface potential and current distribution and promote electrocatalytic activity between polar plates. Whereas comparison between Ti-Al and Ti-Cu laminated composites, Ti-Cu laminated composites is better in performance.

Preliminary Research on Interfacial Evolution Behaviour of Ti-Cu Laminated Composite Materials

Ti-Cu laminated composites were fabricated by means of vacuum hot pressing (VHP). The Ti-Cu interfacial reaction was studied to observe the microstructural changes. Scanning Electron Microscopy (SEM), Energy Disperse Spectroscopy (EDS) and X-Ray Diffraction (XRD) were used to observe morphology and analyze phase composition of interfacial reaction zones. With increasing the holding time, the thickness of the reaction zones varies from 12μm to 16μm. The results show that there are 5 binary intermetallic compounds (Cu4Ti, Cu4Ti3, CuTi, Cu3Ti2, CuTi2) observed in the Ti-Cu diffusion couples held at 1073 K for 1h, 1.5h, 2h and 2.5h respectively under the pressure of 10MPa.

Preliminary Study of Oxygen Evolution Ti-Al Composite Anode

This text used by hot-pressing diffusion welding to obtain Ti-Al laminated composite anode.The interfacial morphology and interface reaction of Ti-Al laminated composite anode were analyzed by means of scanning electron microscopy(SEM) and EDS. The Ti/IrO2-Ta2O5 were got by typical oxygen evolution model coating ingredient(mole ratio of Ir to Ta was 7:3) and the sides of Titanium were examined by using electrochemical workstation.This text results indicated that the interfacial thickness varied from 462nm to 792nm with the increase of holding time and increased from 396nm to 1.25µm with temperature rising. Under the same condition of hot-pressing diffusion welding,the thickness of diffusion interface layer with aluminum sheets by previous cold rolling (1.25µm) is thicker than non-cold rolling(924nm),increasing by 35.28%. Ti-Al laminated composite anodes by using hot-pressing diffusion welding showed better performances than the industrial titanium.The oxygen evolution anode showed the best performance by holding at 833 K for 2h under the pressure of 6MPa.This will play a role in the energy saving.

Preparation and Characterisation of Al/Pb Layered Composite Materials

Taking Sn as the third element in the Al/Pb immiscible system, the Al-Sn-Pb layered composite materials at different temperatures were prepared by solid-liquid coating method. Microstructure of the layered composite materials was studied by scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS), and then the flexural strength and interface adhesion of the layered composite materials were measured. The results showed that, introducing of Sn reduced the enthalpy heat of mixing of Al/Pb system to be negative, and inter-diffusion of elements in the interface region occurred, and a metallurgical bonding interface between Pb and Al formed. The optimum diffusion-sintering temperature-time for the best flexural strength were determined by 250οС , 0.5h, respectively. Under the controlled conditions, the mechanism was discussed.