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Computer Simulation and X-ray Diffraction of Nanocrystals

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Journal of Materials Science & technology 2001年第3期17卷 333-337页

作者： Ming CHANG, Baohe YANG and Xiaolu XI tianjin institute of technology, tianjin 300191, China Hao CHANG Hefei institute of technology, Hefei 230009, China E-mail: changm@*** tianjin inst technol Tianjin 300191 Peoples R China Hefei inst technol Hefei 230009 Peoples R China

X-ray diffraction of structure in nanocrystalline alpha -Fe and Cu was studied by atomistic simulation. Atomic position equilibrium was reached by using molecular dynamics method to simulate nanocrystalline structure with Finnis potentials to model interatomic interactions. It was found that the boundary component exhibits short-range order, and the distortion in crystalline component increases with the decrease of grain size.

关键词： Computer Simulation and X-ray Diffraction of Nanocrystals Simulation

Laser Surface Remelting of Fe-based Alloy Coating Deposited by APS

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稀有金属材料与工程 2012年第S1期41卷 407-413页

作者： Fu Teng Ye Fuxing Wei Haihong Cui Chong tianjin Univ Sch Mat Sci & Engn Tianjin 300072 Peoples R China tianjin Key Lab adv Joining technol Tianjin 300072 Peoples R China

The Fe-based amorphous alloy coatings with different porosities were deposited on Q235 steel substrates by means of atmospheric plasma spraying(APS).The as-sprayed coatings were remelted by the facility of a Nd:YAG laser to further enhance their compactness and bonding strength via orthogonal experiment *** effects of laser remelting on the microstructure,phase compositions and mechanical properties of the as-sprayed coatings were investigated by optical microscopy,scanning electron microscope,X-ray diffraction and Vickers microhardness *** corrosion performance of the coatings was evaluated by both potential dynamic measurements(PDM)and electrochemical impedance spectroscopy(EIS)in a 10%NaOH *** results indicate that laser power of 700 W,scanning velocity of 4 mm/s,beam size of 3 mm and porosity of 1.19%are the optimized remelting process *** laser-remelted coatings exhibite more homogenous structure as strong metallurgical bonding to *** amorphous phases in the as-sprayed coatings crystallize toα-Fe,Fe2Si,Fe3.5B,and Fe2W phases for the high temperature and rapid solidification in the remelting *** microhardness values of as-sprayed are in the range of 700-800 HV0.1,while the microhardness values of the remelted coatings are enhanced slightly to 750-850 *** PDM and EIS analysis results show that the remelted coatings exhibite relatively excellent corrosion resistance compared with the stainless steel 1Cr18Ni9Ti,however the corrosion resistance of the remelted coatings is inferior to the as-sprayed amorphous coatings.

关键词： Fe-based amorphous alloy coating plasma spraying laser surface remelting corrosion resistance

OBSERVATIONS ON DEFORMATION BEHAVIOR OF HIGH PERFORMANCE FIBERS BY POLARIZING OPTICAL MICROSCOPY

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Chinese Journal of Polymer Science 2000年第1期18卷 81-86页

作者： Chang-fa Xiao Yu-feng Zhang Department of Materials Science, tianjin institute of Textile Science and technology, tianjin 300160, China tianjin inst Text Sci & technol Dept Mat Sci Tianjin 300160 Peoples R China

By means of polarizing optical microscopy (POM), deformation behavior of four kinds of fibers, i.e, ultra high molecular weight polyethylene (UHMW-PE) fiber, polyvinyl alcohol (PVA) fiber, polyethylene terephthalate (PET) fiber, and wholly aromatic (rho-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) copolyester [P(HBA/HNA)]/PET (ACPET blend) fiber, in axial compression, axial impacting, and bending was observed. In compression, kink bands formed at an angle of 55-60 degrees ro the fiber axis in 10-times-drawn UHMW-PE fiber, 75-80 degrees in 40-times-drawn sample, 80 degrees in PVA fiber, and 90 degrees in the ACPET blend fiber. In impacting and bending, band angles of UHMW-PE, PVA and PET fibers are nearly the same as those formed in compression, indicating that slip systems do not change. For any of the four kinds of fiber, band spacing exhibits great differences in compression, in impacting, and in bending, which may be attributed to the differences in the degrees of strain or stress concentration.

关键词： high performance fiber axial compression axial impacting bending

Study on Co-Permeation of Solid Rare Earth, Boron and Vanadium

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Journal of Rare Earths 2001年第2期19卷 149-152页

作者：陶小克董桂霞彭日升孙永昌 tianjin inst technol Dept Mat Sci & Engn Tianjin 300191 Peoples R China

The effect of rare earth compound of CeCl3 on the kinetic process, composition, microstructure and mechanical properties of co-permeating of solid powder boron-vanadium (B-V) was investigated. The results indicate that the addition of CeCl3 to permeating agent not only has obviously catalytic effect on permeating rate, which increases by more than 40%, hut also greatly improves the hardness and abrasion resistant of the permeating layer owing to the formation of new phase of CeFe2 after Ce permeates into the layer of the part as an alloying ingredient. It is believed that rare earth elements accelerate the permeating rate of B and V by increasing the potentials of B and V of the agent, activating the surface of the workpiece, and decreasing the activation energy of diffusion of the B and V atoms.

关键词： rare earths boron potential vanadium potential co-permeation of rare earth boron and vanadium

An Optimal Pricing and Ordering Policy with Trapezoidal-Type Demand Under Partial Backlogged Shortages

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TSINGHUA SCIENCE AND technolOGY 2024年第6期29卷 1709-1727页

作者： Xu, Chunming Bai, Mingfei Wu, Chenchen Wang, Qiyue Wang, Yiwei tianjin Univ technol Inst Operat Res & Syst Engn Coll Sci Tianjin 300384 Peoples R China tianjin Univ technol Sch Elect & Elect Engn Tianjin 300384 Peoples R China

Based on the retail inventory operation of Heilan Home, this study incorporates the price factor into inventory environment involving trapezoidal time-varying products. A joint pricing and ordering issue with deteriorating items under partial backlogged shortages is firstly explored in a fixed selling cycle. The corresponding optimization model aiming at maximizing profit performance of inventory system is developed, the theoretical analysis of solving the model is further provided, and the modelling frame generalizes some inventory models in the existing studies. Then, a solving algorithm for the model is designed to determine the optimal price, initial ordering quantity, shortage time point, and the maximum inventory level. Finally, numerical examples are presented to illustrate the model, and the results show the robustness of the proposed model.

关键词： Analytical models Sensitivity analysis Pricing Robustness Numerical models inventory trapezoidal-type demand pricing deteriorating items partial backlogged shortages

Aging Effect on Configuration of Dislocations in Parent Phase of a Thermomechanically Trained Cu-Zn-Al Alloy

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Journal of Materials Science & technology 1995年第6期11卷 415-417页

作者： ZHANG, QG GAO, JS GU, NJ YIN, FX HEBEI inst technol TIANJIN 300130PEOPLES R CHINA

With electron microscopic investigation, the configuration of dislocations in an aged Cu-25.72Zn-4.21Al (wt-%) shape memory alloy was found to be in the form of superdislocations and their jogs, which were different from the preferential dislocations regularly aligned in an unaged alloy. These defects generated during aging treatment were considered to be responsible for low fatigue life.

关键词： Copper alloys

Sideband Absorption and its Effects on Temperature Dependence of Local Vibrational Mode Main Absorption Band for Carbon Acceptor in Gallium Arsenide

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Rare Metals 1999年第4期18卷 305-310页

作者：杨瑞霞李光平 Hebei Univ technol Dept Elect Engn Tianjin 300130 Peoples R China tianjin Elect Mat Res inst Tianjin 300192 Peoples R China

The local vibrational mode (LVM) optical absorption band of carbon acceptor was investigated carefully. Because of the appearance of a sideband on the low energy side of the LVM main absorption band, it is found that the measured value of the integrated area for the main absorption band is sensitive to the choice of integration baseline wavenumber range (BWR). This is the main cause that the experimental results from different investigators show a wide spread for the temperature dependence of the integrated area. The origin of the sideband is also discussed.

关键词： carbon acceptor local vibrational mode excited state

Numerical investigation of turbulent mass transfer processes in turbulent fl uidized bed by computational mass transfer

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CHINESE JOURNAL OF CHEMICAL ENGINEERING 2024年第12期76卷 64-74页

作者： Ren, Hailun Zeng, Liang Li, Wenbin Chen, Shuyong Tang, Zhongli Zhang, Donghui tianjin Renai Coll Dept Chem Engn Tianjin 301636 Peoples R China tianjin Univ Sch Chem Engn & Technol Tianjin 300072 Peoples R China Innovat Ctr adv Glass Mat Anhui Co Ltd Bengbu 233000 Peoples R China tianjin Univ Res Ctr Chem Engn Sch Chem Engn & Technol Tianjin 300072 Peoples R China

Turbulent fluidized bed possesses a distinct advantage over bubbling fluidized bed in high solids contact efficiency and thus exerts great potential in applications to many industrial processes. Simulation for fluidization of fluid catalytic cracking (FCC) particles and the catalytic reaction of ozone decomposition in turbulent fluidized bed is conducted using the Eulerian-Eulerian approach, where the recently developed two-equation turbulent (TET) model is introduced to describe the turbulent mass diffusion. The energy minimization multi-scale (EMMS) drag model and the kinetic theory of granular flow (KTGF) are adopted to describe gas-particles interaction and particle-particle interaction respectively. The TET model features the rigorous closure for the turbulent mass transfer equations and thus enables more reliable simulation. With this model, distributions of ozone concentration and gas-particles two-phase velocity as well as volume fraction are obtained and compared against experimental data. The average absolute relative deviation for the simulated ozone concentration is 9.67% which confirms the validity of the proposed model. Moreover, it is found that the transition velocity from bubbling fluidization to turbulent fluidization for FCC particles is about 0.5 m$s-1 which is consistent with experimental observation. (c) 2024 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： Turbulent fluidized bed Simulation Computational mass transfer Turbulence Computational fluid dynamics

Influence of Isovalent Impurity Ge on Nucleation and Morphology of Supersaturated Oxygen Precipitate in CZSi

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Rare Metals 2000年第3期19卷 217-221页

作者：张维连檀柏梅张颖怀孙军生张志成 Hebei Univ technol Inst Semicond Mat Tianjin 300130 Peoples R China

The effects of Ge in CZSi on the density and the rate of nucleation of supersaturated oxygen precipitation at lower annealing temperatures were *** is discovered that rod like precipitation was suppressed when annealing at 700℃,but Ge has no effect on the morphology and the growth of oxygen precipitation at annealing temperatures more than 900℃.The results indicated that Ge neither acted as center of nucleation nor was involved in oxygen precipitation and its defect.

关键词： CZSi Oxygen precipitation Nucleation Doping(Ge) Annealing