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Adsorption of sodium ions and hydrated sodium ions on a hydrophobic graphite surface via cation-π interactions

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Chinese Physics B 2011年第6期20卷 474-479页

作者：石国升王志刚赵纪军胡钧方海平 Shanghai institute of Applied Physics Chinese Academy of Sciences Laboratory of Material Modification by laser Electron and Ion Beams and the College of Advanced Science and Technology Dalian University of Technology

Using density functional theory computation, we show that sodium ions and hydrated sodium ions can be strongly adsorbed onto a hydrophobic graphite surface via cation-π interactions. The key to this eation-π interaction is the coupling of the delocalized π states of graphite and the empty orbitals of sodium ions. This finding implies that the property of the graphite surface is extremely dependent on the existence of the ions on the surface, suggesting that the hydrophobic property of the graphite surface may be affected by the existence of the sodium ions.

关键词： graphite sodium ion and hydrated sodium ion cation-π interaction density functional theory

Influences of nitrogen flow rate on the structures and properties of Ti and N co-doped diamond-like carbon films deposited by arc ion plating

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Chinese Physics B 2014年第4期23卷 616-621页

作者：张林马国佳林国强马贺韩克昌 Key Laboratory for Material Modification by laser Ion and Electron Beams Dalian University of Technology science and technology on Power Beam Processes Laboratory Beijing Aeronautical Manufacturing Technology Research Institute

In this paper, Ti-C-N nanocomposite films are deposited under different nitrogen flow rates by pulsed bias arc ion plating using Ti and graphite targets in the Ar/N2 mixture gas. The surface morphologies, compositions, microstructures, and mechanical properties of the Ti-C-N films are investigated systematically by field emission scanning electron mi- croscopy （FE-SEM）, x-ray photoelectron spectroscopy （XPS）, grazing incident x-ray diffraction （GIXRD）, Raman spectra, and nano-indentation. The results show that the nanocrystalline Ti（C,N） phase precipitates in the film from GIXRD and XPS analysis, and Raman spectra prove the presence of diamond-like carbon, indicating the formation of nanocomposite film with microstructures comprising nanocrystalline Ti（C,N） phase embedded into a diamond-like matrix. The nitrogen flow rate has a significant effect on the composition, structure, and properties of the film. The nano-hardness and elastic modulus first increase and then decrease as nitrogen flow rate increases, reaching a maximum of 34.3 GPa and 383.2 GPa, at a nitrogen flow rate of 90 sccm, respectively.

关键词： arc ion plating Ti-C-N film nitrogen flow rate microstructure

Numerical study on the characteristics of nitrogen discharge at high pressure with induced plasma

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Chinese Physics B 2012年第7期21卷 382-388页

作者：王一男刘悦郑殊林国强 Key Laboratory of Materials Modification by laser Ion and Electron beams Dalian University of Technology

Based on the fluid theory of plasma, a model is built to study the characteristics of nitrogen discharge at high pressure with induced argon plasma. In the model, species such as electrons, N2+, N4+, Ar+, and two metastable states (N 2(A3∑u+), N2 (a1 ∑u-)) are taken into account. The model includes the particle continuity equation, the electron energy balance equation, and Poisson抯equation. The model is solved with a finite difference method. The numerical results are obtained and used to investigate the effect of time taken to add nitrogen gas and initially-induced argon plasma pressure. It is found that lower speeds of adding the nitrogen gas and varying the gas pressure can induce higher plasma density, and inversely lower electron temperature. At high-pressure discharge, the electron density increases when the proportion of nitrogen component is below 40%, while the electron density will keep constant as the nitrogen component further increases. It is also shown that with the increase of initially-induced argon plasma pressure, the density of charged particles increases, and the electron temperature as well as the electric field decreases.

关键词： induced plasma nitrogen discharge numerical simulation

Numerical Calculation and Experimental Research on Crack Arrest by Detour Effect and Joule Heating of High Pulsed Current in Remanufacturing

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Chinese Journal of Mechanical Engineering 2014年第4期27卷 745-753页

作者： YU Jing ZHANG Hongchao DENG Dewei HAO Shengzhi IQBAL Asif institute of Sustainable Design and Manufacture Dalian University of Technology School of Materials science and Engineering Dalian University of Technology Key Laboratory of Materials Modification by laser Ion and Electron Beams of Ministry of EducationDalian University of Technology

The remanufacturing blanks with cracks were considered as irreparable. With utilization of detour effect and Joule heating of pulsed current, a technique to arrest the crack in martensitic stainless steel FV520B is developed. According to finite element theory, the finite element（FE） model of the cracked rectangular specimen is established firstly. Then, based on electro-thermo-structure coupled theory, the distributions of current density, temperature field, and stress field are calculated for the instant of energizing. Furthermore, the simulation results are verified by some corresponding experiments performed on high pulsed current discharge device of type HCPD-I. Morphology and microstructure around the crack tip before and after electro pulsing treatment are observed by optical microscope（OM） and scanning electron microscope（SEM）, and then the diameters of fusion zone and heat affected zone（HAZ） are measured in order to contrast with numerical calculation results. Element distribution, nano-indentation hardness and residual stress in the vicinity of the crack tip are surveyed by energy dispersive spectrometer（EDS）, scanning probe microscopy（SPM） and X-ray stress gauge, respectively. The results show that the obvious partition and refined grain around the crack tip can be observed due to the violent temperature change. The contents of carbon and oxygen in fusion zone and HAZ are higher than those in matrix, and however the hardness around the crack tip decreases. Large residual compressive stress is induced in the vicinity of the crack tip and it has the same order of magnitude for measured results and numerical calculation results that is 100 MPa. The relational curves between discharge energies and diameters of the fusion zone and HAZ are obtained by experiments. The difference of diameter of fusion zone between measured and calculated results is less than 18.3%. Numerical calculation is very useful to define the experimental parameters. An effective method to

关键词： remanufacturing crack arrest numerical simulation microstructure high pulse current

Effect of grain size on gas bubble evolution in nuclear fuel:Phase-field investigations

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Chinese Physics B 2024年第1期33卷 563-572页

作者：孙丹杨青峰赵家珺高士鑫辛勇周毅尹春雨陈平赵纪军王园园 science and technology on Reactor System Design technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China Key Laboratory of Materials Modification by laser Ionand Electron BeamsDalian University of TechnologyDalian 116024China

Numerous irradiation-induced gas bubbles are created in the nuclear fuel during irradiation, leading to the change of microstructure and the degradation of mechanical and thermal properties. The grain size of fuel is one of the important factors affecting bubble evolution. In current study, we first predict the thermodynamic behaviors of point defects as well as the interplay between vacancy and gas atom in both UO_(2) and U_(3)Si_(2) according to ab initio approach. Then, we establish the irradiation-induced bubble phase-field model to investigate the formation and evolution of intra-and inter-granular gas bubbles. The effects of fission rate and temperature on the evolutions of bubble morphologies in UO_(2) and U_(3)Si_(2) have been revealed. Especially, a comparison of porosities under different grain sizes is examined and analyzed. To understand the thermal conductivity as functions of grain size and porosity, the heat transfer capability of U_(3)Si_(2) is evaluated.

关键词： grain size point defects fission gas bubble

Effects of secondary electron emission on plasma characteristics in dual-frequency atmospheric pressure helium discharge by fluid modeling

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Chinese Physics B 2019年第2期28卷 346-351页

作者： Yi-Nan Wang Shuai-Xing Li Yue Liu Li Wang College of science Liaoning Shihua University Key Laboratory of Materials Modification by laser Ion and Electron Beams(Ministry of Education)Dalian University of Technology

A one-dimensional(1D) fluid simulation of dual frequency discharge in helium gas at atmospheric pressure is carried out to investigate the role of the secondary electron emission on the surfaces of the electrodes. In the simulation, electrons,ions of He^+ and He_2^+, metastable atoms of He*and metastable molecules of He*_2 are included. It is found that the secondary electron emission coefficient significantly influences plasma density and electric field as well as electron heating mechanisms and ionization rate. The particle densities increase with increasing SEE coefficient from 0 to 0.3 as well as the sheath's electric field and electron source. Moreover, the SEE coefficient also influences the electron heating mechanism and electron power dissipation in the plasma and both of them increase with increasing SEE coefficient within the range from 0 to 0.3 as a result of increasing of electron density.

关键词： dual frequency secondary electron emission atmospheric pressure discharge

Dynamics of Dust in a Plasma Sheath with Magnetic Field

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Plasma science and technology 2007年第4期9卷 394-397页

作者：段萍刘金远宫野刘悦王晓钢 State Key Laboratory of Material Modification by laser Electron and Ion BeamsDepartment of Physics and College of Advanced Science and TechnologyDalian University of TechnologyDalian 116024China College of Physics Science and TechnologyDalian UniversityDalian 116622China State Key Laboratory of Material Modification by laser Electron and Ion BeamsDepartment of Physics and College of Advanced Science and TechnologyDalian University of TechnologyDalian 116024China

Dynamics of dust in a plasma sheath with a magnetic field was investigated using a single particle model. The result shows that the radius, initial position, initial velocity of the dust particles and the magnetic field do effect their movement and equilibrium position in the plasma sheath. Generally, the dust particles with the same size, whatever original velocity and position they have, will locate at the same position in the end under the net actions of electrostatic, gravitational, neutral collisional, and Lorentz forces. But the dust particles will not locate in the plasma sheath if their radius is beyond a certain value.

关键词： plasma sheath magnetic field dust particles

Three dimensional microstructures and wear resistance of Al-Bi immiscible alloys with different grain refiners

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science China(Technological sciences) 2015年第5期58卷 870-875页

作者： WANG TongMin CAO Fei CHEN ZongNing KANG HuiJun ZHU Jing FU YaNan XIAO TiQiao LI TingJu Key Laboratory of Materials Modification by laser Ion and Electron Beams (Ministry of Education) School of Material Science and Engineering Dalian University of Technology Shanghai institute of Applied Physics Chinese Academy of Sciences

The three dimensional(3D) microstructures of Al-Bi alloys with different grain refiners(Al-5Ti-B, Al-3B and Al-3Ti) have been studied using synchrotron X-ray microtomography. The relationships between the microstructures and the corresponding wear behavior are verified through the friction and wear tests. The worn surfaces of the samples with grain refiners tested under 15 and 60 N loads are analyzed using Scanning Electron Microscopy(SEM). The results indicate that the addition of grain refiners is beneficial to the size and distribution of the Bi-rich particles in Al-Bi alloys. Compared with Al-5Ti-B and Al-3B grain refiners, the Bi-rich particles are more uniformly distributed and spherical with finer size with the addition of Al-3Ti grain refiner. The refinement renders the Al-20wt%Bi alloy refined by Al-3Ti the superior wear resistance with respect to those refined by Al-5Ti-B and Al-3B grain refiners, corresponding to the microstructures with fine and uniformly distributed Bi-rich particles in the Al matrix.

关键词： finer uniformly Electron refined verified refinement spherical friction adding dispersed

Influence of Nitrogen Vacancy Concentration on Mechanical and Electrical Properties of Rocksalt Zirconium Nitride Films

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Acta Metallurgica Sinica(English Letters) 2017年第11期30卷 1100-1108页

作者： Ke-Chang Han Guo-Qiang Lin Chuang Dong Kai-Ping Tai Xin Jiang Key Laboratory for Material Modification by laser Ion and Electron Beams(Ministry of Education)Dalian University of Technology institute of Metal Research Chinese Academy of Sciences

To study the influence of the nitrogen vacancy （VN） on mechanical and electrical properties of zirconium nitride deeply, ZrNx films with different VN concentrations were synthesized on the Si （111） substrates by enhanced magnetic filtering arc ion plating. The morphologies, microstructures, residual stresses, compositions, chemical states, mechanical and electrical properties of the as-deposited films were characterized by field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, Nanoindenter and Hall effect measurements. The results showed that ZrNx films exhibited rocksalt single-phase structure within a VN concentration ranging from 26 to 5%. The preferred orientation, thickness, grain size and residual stress of the ZrNx films kept constant at different VN concentrations. Both the nanohardness and elastic modulus first increased and then decreased with the decrease in VN concentration, reaching the peaks around 16%. And the electric conductivity of the ZrNx films showed a similar tendency with nanohardness. The underlying atomic-scale mechanisms of VN concentration-dependent hardness and electric conductivity enhancements were discussed and attributed to the different electronic band structures, rather than conventional meso-scale factors, such as preferred orientation, grain size and residual stress.

关键词： ZrN_x films Nitrogen vacancy Hardness Electrical properties Band structure