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Cathodic electrochemical behavior in Na_3AlF_6-Al_2O_3-LiF-based melts at tungsten electrode with various cryolite ratios

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Rare Metals 2018年第1期37卷 40-46页

作者： Shao-Hu Tao Yue-Zhong Di jian-ping peng Ke-Jia Liu Ying-Long Li Nai-Xiang Feng School of Metallurgy and Materials Northeastern University

The cathodic behavior at tungsten electrode in Na3AlF6-Al2O3-LiF-based melt with various cryolite ratios was investigated by means of potentiodynamic cathodic polarization, potentiostatic electrolysis, chronopotentiometry, and open-circuit chronopotentiometry. The results show that the formation process of Al-W intermetallic compound is controlled by both diffusion and charge transfer when the cryolite ratio is below 2.5, and is completely controlled by diffusion when cryolite ratio is above2.5. The deposition process of metal aluminum is completely charge-transfer controlled. Sodium vapor releases along with the deposition of metal aluminum as crylite ratio increases, which leads to a great influence on current efficiency. When the cryolite ratio is lower than 2.0, the critical cathodic current density of deposited aluminum at tungsten electrode is about 150 mA·cm^（-2）,but the current density is above 200 mA·cm^（-2） under other experimental conditions. A higher cryolite ratio can cause a higher cathodic overvoltage. The relative content of Al layer is higher with the decrease of cryolite ratio, and Al layer easily strips into the molten salt when the cryolite ratio is higher than 2.5.

关键词： LiF Cryolite ratio Aluminum electrolysis Cathodic electrochemistry

Process of producing magnesium by thermal vacuum reduction using silicocalcium as reductant

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Rare Metals 2016年第7期35卷 571-575页

作者： Yao-Wu Wang Kun Zhao jian-ping peng Yue-Zhong Di Ying-Long Li Yang Song Xin-Zhong Deng School of Materials and Metallurgy Northeastern University

A new process of producing magnesium by thermal vacuum reduction using dolomite and magnesite as materials and silicocalcium as reductant was studied in this study. The reduction process of MgO by silicocalcium was analyzed by phases analysis of reduction slag through X-ray diffraction （XRD） and the factors influencing the reduction ratio of MgO were investigated. The experi- mental results show that when using silicocalcium as reductant, the reduction ratio of MgO can be over 93 %. In the reduction process, calcium in silicocalcium takes part in the reduction reaction of MgO firstly below 1,000 ℃ and it makes CaSi2 decompose. It also releases elemental silicon which has more reactive activity and improves the reduction reaction of MgO. That is the main cause that the reduction ratio of MgO using silicocalcium as reductant is 8 %-10 % higher than that by Pidgeon process using fer- rosilicon as reductant under the same conditions.

关键词： Pidgeon process Thermal vacuum reduction Magnesium Silicocalcium

Phase regulated suppression and enhancement switches of four-wave mixing and fluorescence

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Frontiers of physics 2014年第2期9卷 153-156页

作者： Zhi-Guo Wang peng Ying Pei-Ying Li Hua-Yan Lan He-Qing Huang Hao Tian jian-ping Song Yan-peng Zhang Key Laboratory for Physical Electronics and Devices of the Ministry of Education Shaanxi Key Lab of Information Photonic Technique Xi'an Jiaotong University Xi'an 710049 China

We experimentally study the phase regulated switch between elcctromagnctically induced trans- parency and electromagmetically induced absorption in probe transmission signal and the conver- sion between enhancement and suppression in four-wave mixing and fluorescence signals for the first time. By changing the relative phase, electromagnetically induced transparency can be eonverted into electromagnetically induced absorption. In this process, the conversion from suppression to enhancement is also obtained in four-wave mixing and fluorescence signals. This research can be applied in non-linear optical device like optical switch and optical wavelength convertor.

关键词： four-wave mixing fluorescence phase regulation enhancement and suppression

Influence of particle size on the breaking of aluminum particle shells

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Chinese Physics B 2022年第7期31卷 454-460页

作者： Tian-Yi Wang Zheng-Qing Zhou jian-ping peng Yu-Kun Gao Ying-Hua Zhang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Zhaojin Mining Industry Co. LtdZhaoyuan 265400China

Rupturing the alumina shell(shell-breaking)is a prerequisite for releasing energy from aluminum *** stress overload in a high-temperature environment is an important factor in the rupture of the alumina *** Multiphysics was used to simulate and analyze the shell-breaking response of micron-scale aluminum particles with different particle sizes at 650℃in *** simulation results show that the thermal stability time and shell-breaking response time of 10μm–100μm aluminum particles are 0.15μs–11.44μs and 0.08μs–3.94μs,*** also reveal the direct causes of shell breaking for aluminum particles with different particle *** the particle size is less than 80μm,the shell-breaking response is a direct result of compressive stress *** the particle size is between80μm and 100μm,the shell-breaking response is a direct result of tensile stress *** article provides useful guidance for research into the energy release of aluminum powder.

关键词： aluminum particle shell–core structure thermal stress shell-breaking

Entropy of a Free Quantum Particle

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Journal of Modern Physics 2012年第12期3卷 1914-1917页

作者： jian-ping peng Department of Physics Shanghai Jiao Tong University Shanghai China

The time-dependent entropy of a single free quantum particle in the non-relativistic regime is studied in detail for the process started from a fully coherent quantum state to thermodynamic equilibrium with its surroundings at a finite temperature. It is shown that the entropy at the end of the process converges to a universal constant, as a result of thermal interaction.

关键词： Entropy Generation Quantum Thermodynamic Systems

Temperature Dependent Motion of a Massive Quantum Particle

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Journal of Modern Physics 2012年第7期3卷 610-614页

作者： jian-ping peng Department of Physics Shanghai Jiao Tong University Shanghai China

We report model calculations of the time-dependent internal energy and entropy for a single quasi-free massive quantum particle at a constant temperature. We show that the whole process started from a fully coherent quantum state to thermodynamic equilibrium can be understood, based on statistics of diffracted matter waves. As a result of thermal interaction between the particle and its surroundings, the motion of the particle shows new feature.

关键词： Thermodynamics Internal Energy Entropy Generation

Improvement of Pure Random Search in Global Optimization

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Advances in Manufacturing 2000年第2期4卷 92-95页

作者： jian-ping1 peng Ding-hua Shi Shanghai Municipal Commission of Science and Technology Shanghai China College of Sciences Shanghai University Shanghai China

In this paper, the improvement of pure random search is studied. By taking some information of the function to be minimized into consideration, the authors propose two stochastic global optimization algorithms. Some numerical experiments for the new stochastic global optimization algorithms are presented for a class of test problems.

关键词： random search global optimization stochastic global optimization algorithm

Penetration behavior of electrolyte into graphite cathode in NaF-KF-LiF-AlF_(3) system with low cryolite ratios

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Transactions of Nonferrous Metals Society of China 2022年第8期32卷 2727-2735页

作者： Bing-xu CHEN jian-ping peng Yao-wu WANG Yue-zhong DI School of Metallurgy Northeastern UniversityShenyang 110819China

The current study focuses on the electrolyte penetration of the graphite cathode in a NaF−KF−LiF−AlF_(3) aluminum-electrolysis system with a cryolite ratio of *** involves a comprehensive investigation of the electrolyte in the cathode before and after electrolysis by X-ray diffraction and analysis of the results by semi-quantitative calculation in *** results show that KF can promote electrolyte penetration,with higher KF contents resulting in greater *** electrolyte penetration,K_(2)NaAlF_(6) and solid solutions containing KF play important roles in KF-containing *** effectively prevents the electrolyte penetration,while the Na_(3)Li_(3)Al_(2)F_(12) phase plays an essential role in systems with high LiF contents.

关键词： aluminum electrolysis KF LiF cathode penetration electrolyte composition low cryolite ratio

Numerical modeling of effect of slot on bubble motion in aluminum electrolytic process

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Transactions of Nonferrous Metals Society of China 2018年第8期28卷 1670-1678页

作者： Qiang WANG Mei-jia SUN Bao-kuan LI Guang-qiang LI jian-ping peng State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyKey Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of EducationWuhan University of Science and TechnologySchool of MetallurgyNortheastern Universit

A transient three-dimensional（3 D） model was established to understand the bubble motion in an industrial electrolytic process. An anode with a new design was tested. It incorporates two slots that allow an efficient removal of gas bubbles. The electromagnetic fields were described by solving Maxwell＇s equations. The bubble movement was studied with two-way coupling Euler-Lagrange approach. The interplay of current density and bubble nucleation rate was included. The collision and coalescence of bubbles were considered. Random walk module was invoked for involving the chaotic effect of the turbulence. The numerical results were validated by experimental measurements. The results indicate that the current distribution and the bubble nucleation periodically change. Due to the slot, the bubble elimination heavily increases. The contribution of the slot to the bubble removal exceeds 50% in the case of three currents, and the promotion of the slot decays with increasing the current.

关键词： aluminum electrolytic process anodic bubble slot Euler-Lagrange approach numerical simulation