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Performance of TiC coating prepared by in situ conversion of organic carbon film on 316L bipolar plate

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Journal of Iron and Steel Research International 2023年第8期30卷 1562-1573页

作者： Wen-jiao Zhangl yan-li wang School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004GuangxiChina

TiC coating on 316L stainless steel surface is prepared by molten salt disproportionation reaction by using carbon layer converted from organic carbon solution as carbon *** Raman and morphology characterizations show that the carbon layer and TiC coating are successfully prepared on the surface of 316L stainless steel,the prepared carbon layer and 316L matrix have good adhesion,and the prepared TiC coating is smooth and *** the simulated cathodic environment of the proton exchange membrane fuel cell,the potentiostatic and potentiodynamic polarization measurements show that the TiC coating has smaller and more stable current density fluctuation than the 316L stainless steel substrate,and the electrochemical impedance test lasting for 275 h still shows better stable corrosion resistance than that of the 316L stainless steel ***,in the water contact angle and interface contact resistance tests,the TiC coating consistently maintained better hydrophobicity and lower interface contact resistance values than 316L stainless steel.

关键词： Bipolar plate Proton exchange membrane fuel cell TiC coating Disproportionation reaction Corrosion resistance

On Fluorophore Imaging by Diffusion Equation Model:Decompositions and Optimizations

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Acta Mathematicae Applicatae Sinica 2020年第1期36卷 203-222页

作者： li-yan wang Ji-jun liU School of Mathematics S.T.Yau Center of Southeast UniversitySoutheast UniversityNanjing 210096China

Fluorescence imaging is a target-specific molecular imaging technology using absorption coefficient of *** this imaging model governed by an inverse problem for the coupled diffusion system,which describes the interaction of the excitation field from several boundary sources and the corresponding emission field,we reformulate it as an optimization *** solving this non-quadratic optimizing problem,we propose a decomposition scheme,which extracts the horizontal information of the target from the boundary measurement data *** realizability of this hybrid imaging scheme is rigorously proved mathematically for cubic and ellipsoid targets,by constructing an indicator function for the horizontal location of the target *** based on this horizonal location as a good initial guess for the iteration process,the cost functional is optimized efficiently using the trust domain *** implementations are provided to show the validity of the proposed scheme.

关键词： fluorescence imaging diffusion equation inverse problem decomposition optimization numerics

Porous carbon polyhedrons coupled with bimetallic CoNi alloys for frequency selective wave absorption at ultralow filler loading

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Journal of Materials Science & Technology 2022年第8期103卷 34-41页

作者： yan-li wang Guang-Sheng wang Xiao-Juan Zhang Chen Gao School of Chemistry Beihang UniversityBeijing 100191China College of Chemistry and Materials Engineering Beijing Technology and Business UniversityBeijing 100048China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

Combining suitable microstructure and dielectric-magnetic synergy effect is conducive to achieve lightweight,broadband,and high-efficiency microwave absorbing materials within low filler ***,porous carbon polyhedrons coupled with bimetallic CoNi alloys were synthesized by using metalorganic frameworks(MOFs)as a template and subsequent pyrolysis *** analysis indicated that the existence of metal Ni element could influence the wave attenuation capacity effectively,resulting in frequency selective wave absorption ***,the pyrolysis temperature was also closely related to wave absorption *** Co_(2)Ni_(1)/C/PVDF composites calcined at 800℃ possessed outstanding wave absorption performance at an ultra-low filler loading of 5 wt%.The minimum reflection loss value achieved-52 dB(10.8 GHz)under the matched thickness of 3 ***,the broadest effective absorption bandwidth(RLlity was mainly ascribed to magnetic and dielectric loss,impedance matching as well as porous structure effect.

关键词： Porous carbon polyhedrons Bimetallic CoNi alloys Frequency selective wave

SCHEDUliNG JOBS WITH GENERAL LEARNING FUNCTIONS

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Journal of Systems Science and Systems Engineering 2011年第1期20卷 119-125页

作者： li-yan wang Jian-Jun wang Ji-Bo wang En-Min FENG School of Science Shenyang Aerospace University Shenyang 110136 China School of Mathematical Sciences Dalian University of Technology Dalian 116024 China School of Management Dalian University of Technology Dalian 116024 China

This paper deals with single-machine scheduling problems with a more general learning effect based on sum-of-processing-time. In this study, sum-of-processing-time-based learning effect means that the processing time of a job is defined by a decreasing function of the total normal processing time of jobs that come before it in the sequence. Results show that even with the introduction of the sum-of-processing-time-based learning effect to job processing times, single-machine makespan minimization problems remain polynomially solvable. The curves of the optimal schedule of a total completion time minimization problem are V-shaped with respect to iob normal orocessinz times.

关键词： Scheduling single machine learning effect makespan total completion time

Characterization of Impact Deformation Behavior of a Thermally Aged Duplex Stainless Steel by EBSD

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Acta Metallurgica Sinica(English Letters) 2018年第8期31卷 798-806页

作者： Gang liu Shi-Lei li Hai-Long Zhang Xi-Tao wang yan-li wang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing

The effect of thermal aging on phase transformation and impact toughness of an as-cast duplex stainless steel was investigated at room temperature. After long-term thermal aging, the impact toughness decreases significantly and the cracks initiate and propagate more easily. The plastic deformation ability of the ferrite phase decreases after thermal aging,which leads to the degradation of impact toughness. High stress concentration occurs on the grain boundaries of the austenite phase in the aged materials. Meanwhile, high-stress concentration areas are also observed in the austenite phase near the grain boundaries. After long-term thermal aging, pinned dislocations in ferrite and along phase boundaries lead to the high stress concentration. Micro-cracks preferentially initiate in the ferrite phase and propagate via separation of phase boundaries. The blocking influences of spinodal decomposition precipitates and G-phase precipitates are stronger than the effect of grain boundaries and phase boundaries on the dislocation movement.

关键词： Duplex stainless steel Thermal aging Charpy impact toughness EBSD

First-principles Study of NiAl Alloyed with Rare Earth Element Ce

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Journal of Materials Science & Technology 2011年第8期27卷 719-724页

作者： You wang Junqi He Mufu yan Chonggui li liang wang YeZhou Department of Materials Science School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The structural, elastic, and electronic properties of NiAI alloyed with rare earth element （REE） Ce have been investigated by using density functional theory （DFT）. It is found that Ce has a strong AI site preference and causes lattice distortion of NiAI. The calculation of elastic constants shows that Ce increased both the hardness and the ductility of NiAI, which could be explained by the formation of new ionic bonds between AI （and Ni） and Ce and the enhancement of covalent bonds in NisAl7Ce. Our results are in good agreement with the available experimental data and other theoretical results.

关键词： Point defects Electronic states First-principles

An Enhanced LMI Approach for Mixed H2/H∞ Flight Tracking Control

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Chinese Journal of Aeronautics 2011年第3期24卷 324-328页

作者： ZHANG Qingjiang YE Sijun li yan wang Xinmin School of Automation Northwestern Polytechnical University Xi 'an 710072 China

The coupling between the Lyapunov variables and system matrices makes the problem of mixed H2/H∞ flight tracking controller design non-convex. With the aid of enhanced linear matrix inequality （LMI） approach, the non-convex optimization problem is transformed into convex LMI representations. The proposed coupling is eliminated by introducing slack variables. Moreover, a necessary and sufficient condition is derived for the mixed H2/H∞ flight tracking controller which not only stabilizes the controlled system but also satisfies the mixed H2/H∞ performance index in normal case and fault cases. The new enhanced LMI representations provide additional degrees of freedom to solve the non-convex optimization problem, and reduce the conservativeness of the controller design. Simulation results of the aero-data model in a research environment （ADMIRE） model show the advantages of the enhanced LMI approach.

关键词： mixed H2/H∞ control flight control tracking reliable control linear matrix inequality

Efects of thermal aging temperature and Cr content on phase separ-ation kinetics in Fe-Cr alloys simulated by the phase feld method

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International Journal of Minerals,Metallurgy and Materials 2013年第11期20卷 1067-1075页

作者： Shu-xiao li Hai-long Zhang Shi-lei li yan-li wang Fei Xue Xi-tao wang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Suzhou Nuclear Power Research Institute

Phase field simulations of phase separation in Fe-Cr binary alloys were performed by using the Cahn-Hilliard diffusion function. A new mobility model in relation to aging temperature and Cr content was used in the simulations. Two alloys of Fe-30at%Cr and Fe-35at%Cr were investigated at two different aging temperatures of 573 and 673 K. The phase separation kinetics was found to consist of three stages： wavelength modulation, amplitude increase, and coarsening of Cr-enriched regions. A higher thermal aging temperature accelerated the phase separation and increased the wavelength of concentration fluctuation. While the effect of Cr content on the phase separation kinetics was slight, Fe-Cr alloys with a higher Cr content were found to generate a larger number and a finer size of Cr-enriched regions. The simulation results provide consultation for design and safe operation of duplex stainless steel pipes in nuclear power plants.

关键词： stainless steel duplex steel phase separation kinetics nuclear power plants

Effect of thermal aging on the fatigue crack growth behavior of cast duplex stainless steels

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International Journal of Minerals,Metallurgy and Materials 2015年第11期22卷 1163-1170页

作者： Xu-ming Lü Shi-lei li Hai-long Zhang yan-li wang Xi-tao wang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing

The effect of thermal aging on the fatigue crack growth（FCG） behavior of Z3CN20？09M cast duplex stainless steel with low ferrite content was investigated in this study. The crack surfaces and crack growth paths were analyzed to clarify the FCG mechanisms. The microstructure and micromechanical properties before and after thermal aging were also studied. Spinodal decomposition in the aged ferrite phase led to an increase in the hardness and a decrease in the plastic deformation capacity, whereas the hardness and plastic deformation capacity of the austenite phase were almost unchanged after thermal aging. The aged material exhibited a better FCG resistance than the unaged material in the near-threshold regime because of the increased roughness-induced crack closure associated with the tortuous crack path and rougher fracture surface; however, the tendency was reversed in the Paris regime because of the cleavage fracture in the aged ferrite phases.

关键词： stainless steels fatigue crack growth thermal aging embrittlement fracture morphology