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Improved suspension quality and liquid level stability in stirred tanks with Rotor-Stator agitator based on CFD simulation

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Particuology 2023年第11期82卷 64-75页

作者： Cuicui Yin Jiazhen He Yongnan Xiong Zhibo Zhang Xing Luo Yao Shu danfeng long Kaihong Zheng Institute of New Materials Guangdong Academy of SciencesNational Engineering Research Center of Powder Metallurgy of Titanium&Rare MetalsGuangdong Provincial Key Laboratory of Metal Toughening Technology and ApplicationGuangzhou510651China Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou510651China

The solid-liquid mixing is an important operation unit in the preparation of composites by stirring *** quality composite materials need good homogeneity and stable liquid *** this work,the performances of the Rotor-Stator agitator for solid suspension in stirred tank were investigated through CFD modeling,including the homogeneity,power consumption and liquid level *** Eulerian-Eulerian(E-E)multiphase model and the RNG k-εturbulence model were adopted for modeling the multiphase flow and the turbulence effects,*** effect of various important parameters such as stirring speed,particle size,solid loading and the use of baffles were *** a stator structure with array holes outside the rotor can optimize the flow pattern,thereby improving the mixing uniformity and liquid level *** homogeneity and liquid level stability attained by the Rotor-Stator agitator were better than those for the A200(an axial-flow agitator)and the Rushton(a radial-flow agitator).

关键词： Solid-liquid mixing Rotor-Statoragitator Suspension quality Liquid level stability Powerconsumption Computational fluid dynamics(CFD)

Fabrication and characterization of multi-scale coated boron powders with improved combustion performance:A brief review

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Defence Technology（防务技术） 2024年第1期31卷 27-40页

作者： Rui Liu danfeng Yang Kunyu Xiong Ying-Lei Wang Qi-long Yan Science and Technology on Combustion Internal Flow and Thermo-structure LaboratoryNorthwestern Polytechnical UniversityXi'an710072China Xi'an Modern Chemistry Research Institute Xi'an710065China

Boron has high mass and volume calorific values,but it is difficult to ignite and has low combustion *** literature review summarizes the strategies that are used to solve the above-mentioned problems,which include coatings of boron by using fluoride compounds,energetic composites,metal fuels,and metal *** techniques include recrystallization,dual-solvent,phase transfer,electrospinning,*** one of the effective coating agents,the fluorine compounds can react with the oxide shell of boron *** comparison,the energetic composites can effectively improve the flame temperature of boron powder and enhance the evaporation efficiency of oxide film as a condensed *** and metal oxides would react with boron powder to form metal borides with a lower ignition point,which could reduce its ignition temperature.

关键词： Boron powder coating Structure and morphology Condensed phase thermal reaction Ignition and combustion

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面向重用的废弃电路板拆解升温策略

机械工程学报 2014年第17期50卷 124-132页

作者：龙旦风向东张永凯段广洪清华大学机械工程系北京100084

拆解废弃电路板(Printed circuit board,PCB)并重用高价值元器件是一种有效的回收再利用途径。在拆解过程中如果采用不合理工艺极容易导致元器件质量下降,其中塑封芯片内部界面分层是一种常见缺陷。芯片分层通常由过高温度所致,因此有... 详细信息

拆解废弃电路板(Printed circuit board,PCB)并重用高价值元器件是一种有效的回收再利用途径。在拆解过程中如果采用不合理工艺极容易导致元器件质量下降,其中塑封芯片内部界面分层是一种常见缺陷。芯片分层通常由过高温度所致,因此有必要对拆解过程电路板温度场和升温策略开展研究。根据充分熔焊和避免芯片分层这两个目标提出了峰值温度准则和升温速率准则:峰值温度准则要求在确保充分熔焊的前提下尽量降低电路板整体温度;升温速率准则要求先快速升温后缓慢升温。建立了多温区热风加热电路板的模型,并根据此模型提出基于温度场均匀性的拆解升温策略以获得符合两条升温准则的温度曲线。利用自主研制的废弃电路板拆解机进行试验验证,结果表明:利用拆解升温策略得到的先快后慢型升温的温度场均匀性明显优于斜坡型升温;用这两种温度曲线拆解电路板得到的元器件拆解率相差很小;与斜坡型升温相比,拆解升温策略使拆解过程造成的分层芯片比例降低80%。因此,基于温度场均匀性的拆解升温策略在不明显改变拆解率的前提下可有效避免拆解造成芯片分层。

关键词：废弃电路板回收重用拆解温度曲线

Ultrathin surface coating of Cu enabling long-life Zn metal anodes

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Rare Metals 2024年第5期43卷 2125-2135页

作者： Sang-Sang Liu Ya-Ru Liang Wen-long Chen Ze-Hua Wang Yi-long Dai Fu-Gang Qi Zeng-Sheng Ma Xiao-Ping Ouyang School of Materials Science and Engineering Xiangtan UniversityXiangtan 411105China Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education Xiangtan UniversityXiangtan 411105China

Aqueous zinc-ion batteries(AZIBs)are regarded as promising energy storage devices due to their low cost,high capacity,and ecological ***,the severe dendritic growth and side reactions hinder their practical applicability ***,an ultrathin Cu coating layer(~200 nm)is decorated on zinc foils via filtered cathodic vacuum arc deposition technology,aiming to achieve high-performance *** Cu layer effectively suppresses chemical corrosion and hydrogen evolution reactions and enables preferential(002)Zn deposition during the stripping/plating ***,the Cu@Zn anode represents an elongated cycle life over 4,000 h at 2 mA·cm^(-2)/2 mAh·cm^(-2).Even in conditions of high current density of 5 and 10 mA·cm^(-2),the Cu@Zn anode shows prolonged cycling stability exceeding 4000 and 2000 h,*** advantages also bring high Coulombic efficiency of 99.87%under 5 mAh·cm^(-2)in Cu@Ti||Zn half-cell over 1500 ***,the Cu@Zn||MnO_(2)full cell demonstrates a superior cyclability with a specific capacity of 203 mAh·g^(-1)after 500 cycles a1 A·g^(-1).

关键词： Zn ion battery Zn metal anode Zn(002)plane Cu coating

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废弃电路板插装件的自适应磨削拆解方法

机械工程学报 2011年第21期47卷 133-138页

作者：龙旦风向东董晔弘刘楠段广洪清华大学摩擦学国家重点实验室北京100084

将废弃印制电路板(Printed circuit board,PCB)上的元器件拆解之后再分类,能有效提高后续材料分选和回收的效率。PCB上的插装式元器件由于引脚弯曲等原因,所需拆解力很大,常用的方法难以做到有效拆解。为解决这一困难,提出自适应磨削拆... 详细信息

将废弃印制电路板(Printed circuit board,PCB)上的元器件拆解之后再分类,能有效提高后续材料分选和回收的效率。PCB上的插装式元器件由于引脚弯曲等原因,所需拆解力很大,常用的方法难以做到有效拆解。为解决这一困难,提出自适应磨削拆解方法,利用弹簧的自适应调节能力,在处理挠曲不平的PCB时提供较为平稳的法向磨削力。对自适应磨削系统的力学特性进行分析,结论显示在采用合理的磨削参数时,能够快速去除引脚并且不会过多地降低基板的刚度,证明了自适应磨削拆解方法的可行性。基于此自适应磨削系统的原理研制废弃PCB插装式元器件的引脚磨削拆解原型设备,并进行验证试验研究。试验结果表明此方法能够在轻微磨削基板的条件下高效地去除引脚,磨削后元器件的自动脱落率达到90%以上,并且未脱落的元器件与基板的连接强度大幅降低。

关键词：废弃印制电路板印制电路板拆解印制电路板回收引脚去除自适应磨削

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印刷线路板振动拆解模型及其拆解过程分析

机械工程学报 2017年第9期53卷 127-134页

作者：向东吴育家杨继平龙旦风牟鹏清华大学机械工程系北京100084 武汉第二船舶设计研究所武汉430064 中冶赛迪集团有限公司重庆400013

废弃印刷线路板(Printed circuit boards,PCB)上的元器件具有较高的重用价值,而元器件的重用是基于合理的线路板拆解工艺的。目前相关研究多关注拆解力的分析和计算,然而由于拆解时元器件与线路板间存在熔融状态的焊料,即便提供足够大... 详细信息

废弃印刷线路板(Printed circuit boards,PCB)上的元器件具有较高的重用价值,而元器件的重用是基于合理的线路板拆解工艺的。目前相关研究多关注拆解力的分析和计算,然而由于拆解时元器件与线路板间存在熔融状态的焊料,即便提供足够大的拆解力也难以保证元器件被拆解。在基于已建立的拆解力模型,提出综合考虑拆解力和元器件分离位移的拆解能作为拆解准则,并基于这一准则研究了垂直振动激励下元器件的拆解分离过程,分析了废弃线路板在对边简支对边自由的边界条件下强迫振动的模态,基于薄板振动理论建立PCB的运动微分方程,获得PCB的加速度及位移响应;分析了垂直振动拆解中贴片元器件和插装元器件的不同分离过程,并且采用拆解能模型对不同拆解激振频率、位于线路板不同位置、具有不同最小拆解加速度的元器件进行拆解分析;提出以拆解能图来比较元器件实际获得的拆解能与所需的最小拆解能,为拆解工艺参数的确定提供依据。最后在试验中验证拆解能模型的正确性。

关键词：废弃线路板(PCB) 拆解准则振动拆解

Photocatalytic activation of sulfite by N-doped porous biochar/MnFe_(2)O_(4) interface-driven catalyst for efficient degradation of tetracycline

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Green Energy & Environment 2024年第3期9卷 481-494页

作者： long Cheng Yuanhui Ji Jiangsu Province Hi-Tech Key Laboratory for Biomedical Research School of Chemistry and Chemical EngineeringSoutheast UniversityNanjing211189China

A novel photo-catalytic system composed of N-doped biochars(NBCs),MnFe_(2)O_(4) and sulfite activation under ultraviolet(NBCs/MnFe_(2)O_(4)/sulfite/UV)was constructed to realize the efficient eliminate of tetracycline(TC).As the carrier of MnFe_(2)O_(4),NBCs were synthesized from alfalfa,which has large specific surface area,graphite like structure and hierarchical porous *** adsorption isotherm indicated that NBCs/MnFe_(2)O_(4)-2:1 had the best adsorption performance for TC(347.56 mg g^(-1)).Through synergistic adsorption and photocatalysis,the removal rate of TC reached 84%,which was significantly higher than that of MnFe_(2)O_(4).Electrochemical impedance spectroscopy(EIS)and Photoluminescence(PL)characterization results showed that the introduction of NBCs improved the separation efficiency of photogenerated electron and hole pairs and enhanced the photocatalytic ***,the adsorption,degradation mechanism and degradation path of TC by the catalyst were systematically analyzed by coupling HPLC–MS measurement with the theoretical *** the advantages of excellent degradation performance,low cost,easy separation and environmental friendliness of NBCs/MnFe_(2)O_(4),this work was expected to provide a new path for the practical application of biochar.

关键词： Biochar MnFe_(2)O_(4) Sulfite Adsorption Photocatalysis

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 337-350页

作者： Jingou Kuang Zhilin long School of Civil Engineering Xiangtan UniversityXiangtan 411105China

This work constructed a machine learning(ML)model to predict the atmospheric corrosion rate of low-alloy steels(LAS).The material properties of LAS,environmental factors,and exposure time were used as the input,while the corrosion rate as the output.6 dif-ferent ML algorithms were used to construct the proposed *** optimization and filtering,the eXtreme gradient boosting(XG-Boost)model exhibited good corrosion rate prediction *** features of material properties were then transformed into atomic and physical features using the proposed property transformation approach,and the dominant descriptors that affected the corrosion rate were filtered using the recursive feature elimination(RFE)as well as XGBoost *** established ML models exhibited better predic-tion performance and generalization ability via property transformation *** addition,the SHapley additive exPlanations(SHAP)method was applied to analyze the relationship between the descriptors and corrosion *** results showed that the property transformation model could effectively help with analyzing the corrosion behavior,thereby significantly improving the generalization ability of corrosion rate prediction models.

关键词： machine learning low-alloy steel atmospheric corrosion prediction corrosion rate feature fusion

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废旧电路板钎料吹扫去除试验研究

机械工程学报 2010年第19期46卷 192-198页

作者：潘晓勇龙旦风杨继平李中良郅慧四川长虹电器股份有限公司工程技术中心绵阳621000 清华大学摩擦学国家重点实验室北京100084 后勤工程学院军事供油工程系重庆401311

废旧电路板拆解不但是旧元器件重用的必要步骤,而且有利于废旧电路板上不同材料物质的分类收集。现有废旧电路板拆解工艺和拆解设备难以有效拆卸插装元器件,为了实现废旧电路板的自动化拆解,提出一种基于钎料吹扫去除的废旧电路板拆解工... 详细信息

废旧电路板拆解不但是旧元器件重用的必要步骤,而且有利于废旧电路板上不同材料物质的分类收集。现有废旧电路板拆解工艺和拆解设备难以有效拆卸插装元器件,为了实现废旧电路板的自动化拆解,提出一种基于钎料吹扫去除的废旧电路板拆解工艺,并研制了相应的钎料吹扫去除试验设备,用于辅助拆解以插装电子元器件为主的电路板。为了提高钎料去除率和焊点脱钎率,以废旧电视机主板为例,在钎料吹扫去除试验设备上进行钎料去除的正交试验,并在试验条件下确定最优的预热功率、喷嘴缝宽、压缩热气体吹扫角度和电路板运行速度等工艺参数。试验结果表明,基于钎料吹扫去除的拆解工艺能有效拆解插装元器件,焊点脱钎率可达98.1%;试验结果还表明,在采用基于钎料吹扫去除的拆解工艺中,电路板运行速度是影响钎料去除效果的最重要因素,应该适当取值以优化拆解工艺。

关键词：废旧电路板回收吹扫拆卸元器件