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71.
The dynamics of multi-ion exchange is investigated with consideration for electric fields arising in sorbents when the ions with distinct diffusivities are exchanged. A new model for this process is developed. Simulation shows that the electric field can affect the dynamic break-through curves. The proposed model can be used for the creation of a new process of sorbents regeneration and microcomponents concentration. 相似文献
72.
Niranjan Sitapure Hyeonggeon Lee Francisco Ospina-Acevedo Perla B. Balbuena Sungwon Hwang Joseph Sang-II Kwon 《American Institute of Chemical Engineers》2021,67(1):e17073
Li metal anode is the “Holy Grail” material of advanced Lithium-ion-batteries (LIBs). However, it is plagued by uncontrollable dendrite growth resulting in poor cycling efficiency and short-circuiting of batteries. This has spurred a plethora of research to understand the underlying mechanism of dendrite formation. While experimental studies suggest that there are complex physical and chemical interactions between heterogeneous solid-electrolyte interphase (SEI) and dendrite growth, most of the studies do not reveal the mechanisms triggering these interactions. To deal with this knowledge gap, we propose a multiscale modeling framework which couples kinetic Monte Carlo and Molecular Dynamics simulations. Specifically, the model has been developed to account for (a) heterogeneous SEI, (b) dendrite-SEI interactions, and (c) effect of electrolyte on Li electrodeposition and potential dendrite formation. This allows the proposed computational model to be extended to various electrolytes and SEI species and generate results consistent with previous experimental studies. 相似文献
73.
《Journal of the European Ceramic Society》2021,41(16):48-59
Zirconium Carbide (ZrCx) was irradiated with 10 MeV Au3+ ions to a dose of 10 displacements per atoms (dpa) and subsequently with 100 and 300 keV electrons in a transmission electron microscope (TEM). After ion irradiation, dislocation loops were observed in the microstructure and an increase in the number of carbon vacancies was revealed by Raman spectroscopy. Grazing incidence X-ray diffraction (GIXRD) analysis showed that neither amorphization nor oxidation occurred during ion irradiation of the specimen. Subsequent electron irradiation of the pre-implanted ZrCx foil led to formation of nanosized tetragonal ZrO2 precipitates (5−10 nm diameter) on the surface of the TEM lamella. The formation of the new oxide phase was not related to the electron beam-induced heating of the specimen, but to electron stimulated oxidation caused by the residual oxygen inside the transmission electron microscope. Changes in size and density of ZrO2 crystallites were observed between the pristine and ion irradiated ZrCx regions following electron irradiation, suggesting that the initial microstructure of the ZrCx substrate played a key role in the nucleation and growth of the oxide islands. The obtained results provide insights into the microstructural response of ZrCx to different types of radiation and the inadvertent effects of the electron beam during TEM analysis of in-situ and ex-situ ion irradiated ZrCx. Additionally, the findings of this work suggest a method to prepare local ZrO2 nanoprecipitates within ZrCx grains by selective electron beam irradiation. 相似文献
74.
文章主要介绍了运用回归分析方法建立氢化锂车削表面粗糙度预测模型的方法。通过所建立的粗糙度预测模型,研究了车削过程中切削速度、进给量、切削深度对表面粗糙度的影响。经加工试验证明了该表面粗糙度预测模型的有效性,从而实现加工前在确定切削条件下预测和控制表面粗糙度的目的。 相似文献
75.
AISI 5140 low alloy steel was ion nitrided under different process parameters including time (1, 4, 8 and 12 h), temperature (400, 450, 500 and 550 °C) and gas mixture ratio (0.05, 0.33, 1 and 3 N2/H2). By determining the fatigue strength, surface hardness, compound layer thickness and case depth, the optimum working conditions were determined by using a Taguchi design of experiment. After ion nitriding process, it is aimed to maximize fatigue strength, surface hardness and case depth as well as to minimize compound layer thickness. While the optimum conditions were determined, due to the goals (above aims) more than one being, the trade-off among goals was considered. First of all, each goal was optimised, separately. Then, all the goals were optimised together, considering the priority of the goals, and the optimum results were obtained at 0.05 N2/H2 gas mixture ratio, at the temperature of 450 °C and for 12 h process time. 相似文献
76.
Ion implantation is a versatile tool for the formation of compound semiconductor nanocrystal precipitates in a host medium with the ultimate goal to form quantum dots for use in device technology. Low dose (1 × 1016 cm−2) implantations of tellurium and zinc ions have been performed in a 250 nm thick SiO2 layer thermally grown on 1 1 1 silicon. Their respective energies (180 and 115 keV) have been chosen to produce 5–10 at.% profiles overlapping at a mean depth of about 100 nm. Subsequent thermal treatments at 700 and 800 °C lead to the formation of nanometric precipitates of the compound semiconductor ZnTe. Their size, crystalline structure and depth distribution have been studied as a function of annealing temperature using transmission electron microscopy (TEM) and Rutherford backscattering spectrometry. For the lowest temperature the TEM images shows a cloudy band of ZnTe, but for the highest temperature, the ZnTe nanocrystals are self organized into two layers parallel to the surface. Their mean diameter ranges between 4 and 30 nm, as a function of annealing temperature. 相似文献
77.
A study has been carried out in order to establish the possibility for natural water coagulation via its treatment with strong acid cation exchangers modified with FeCl3 or Al2(SO4)3. Various trademarks of ion exchangers have been used, such as Wofatit KPS, Wofatit KS-10, Lewatit S-100, Varion KSM, Amberlite 200 C and Duolite C-26. It has been found that, while using modified ion exchangers the concentration of suspended solids, permanganate oxygen demand and humic acids in treated water are reduced respectively by approximately 95, 86 and 77% with FeCl3 used as modifier, and 92, 80 and 73% with Al2(SO4)3 as a modifier. The modified ion exchangers can be used for pretreatment of natural water needed for small water make up installations of a module principle. Different modules of these installations can be regenerated in a central station. A scheme has been proposed for natural water treatment combining the process of coagulation with modified ion exchangers and Na-Cl-ion exchange in a mixed bed filter. This can produce conditioned water suitable for thermal plants or for subsequent membrane desalting process. 相似文献
78.
磷酸铁锂锂离子电池正极材料的研究 总被引:1,自引:0,他引:1
锂离子电池是绿色高能可充电池,具有工作电压高、比能量大、自放电小、循环寿命长、无记忆效应、无环境污染等突出优点。本文从磷酸铁锂的结构与性能、材料的制备方法、改性、粒径控制等几方面综述了近年来对橄榄石型磷酸铁锂(LiFePO4)锂离子电池正极材料的研究进展。材料的粒度大小及其分布、离子和电子的传导能力对产品的电化学性能影响很大。在制备时,采用惰性气氛、掺杂导电材料和控制晶粒生长制备粉体是获得性能优良的LiFePO4的有效方法。 相似文献
79.
Improved electrochemical performance of LiFePO4 by increasing its specific surface area 总被引:1,自引:0,他引:1
Yonggao Xia 《Electrochimica acta》2006,52(1):240-245
Cathode material LiFePO4 with an excellent rate capability has been successfully prepared by a simple solid state reaction method using LiCH3COO·2H2O, FeC2O4·2H2O and (NH4)2HPO4 as the starting materials. We have investigated the effects of the sintering temperature and mixing time of the starting materials on the physical properties and electrochemical performance of LiFePO4. It was found that the rate capability of LiFePO4 is mainly controlled by its specific surface area and it is an effective way to improve the rate capability of the sample by increasing its specific surface area. In the present study, our prepared LiFePO4 with a high specific surface area of 24.1 m2 g−1 has an excellent rate capability and can deliver 115 mAh g−1 of reversible capacity even at the 5 C rate. Moreover, we have prepared lithium ion batteries based on LiFePO4 as the cathode material and MCMB as the anode material, which showed an excellent cycling performance. 相似文献
80.