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Heterogeneous MXene-based films with graded electrical conductivity towards highly efficient EMI shielding and electrothermal heating

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Nano Research 2024年第8期17卷 7264-7274页

作者： Yu zhang guangcheng zhang Zhonglei Ma Jianbin Qin Xi Shen Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Research Institute for Sports Science and Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

The increasing need for electromagnetic interference(EMI)shielding of electronics in cold environments such as those in aircraft,space exploration,and wearable heaters to avoid hazardous icing conditions or hypothermia requires the development of thin and lightweight EMI shielding materials preferably by absorbing rather than reflecting electromagnetic(EM)waves while also generating heat through energy-efficient electrothermal ***,it is challenging to achieve absorption-dominant EMI shielding and energy-efficient electrothermal heating simultaneously in a thin and lightweight ***,we develop a heterogeneous composite film comprising a porous multi-walled carbon nanotubes(MWCNTs)/bacterial cellulose(BC)film and an aligned MXene/Ag nanowires(NWs)backing via a sequential vacuum filtration *** porous film contains random conductive networks of MWCNTs with moderate conductivity while the aligned MXene sheets atop Ag NWs network affords high conductivity in the backing,giving rise to graded electrical conductivity for absorption-dominant EMI *** increasing Ag NW coverage leads to significantly increased electrical conductivity without increasing the EM wave reflection as well as the density and thickness of the film,yielding excellent specific EMI shielding effectiveness(>8500 dB/(g·cm^(2))),low driving voltage for energy-efficient electrothermal heating(163℃at 2.5 V),and fast response time(60 s)at a low areal density of 0.015 mg/cm^(2).Combining EMI shielding and electrothermal heating,the heterogeneous film developed here are promising contenders for the protection of electronic equipment in low-temperature environment.

关键词： heterogenous composite film MXene electromagnetic interference(EMI)shielding thermal management

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Nature inspired hierarchical structures in nano-cellular epoxy/graphene-Fe3O4 nanocomposites with ultra-efficient EMI and robust mechanical strength

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Journal of Materials Science & Technology 2022年第8期103卷 177-185页

作者： Xun Fan Fengchao Wang Qiang Gao Yu zhang Fei Huang Ronglin Xiao Jianbin Qin Han zhang Xuetao Shi guangcheng zhang Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072PR China NPU-QMUL Joint Research Institute of Advanced Materials and Structures Northwestern Polytechnical UniversityXi’an 710072PR China Shaanxi Coal Chemical Industry Technology Research Institute Co.Ltd Xi’anShaanxi 710070PR China School of Engineering and Materials Science Queen Mary University of LondonMile End RoadLondon E14NSUK

Hierarchical layered structures,whether in a compact form like nacre or a porous manner like bone,are well known for their combined features of high stiffness,strength,and lightweight,inspiring many man-made materials and structures for high performance *** use of nacre/bone like hierarchical structures in polymer nanocomposites can achieve excellent mechanical and functional properties with high filler volume fractions after carefully aligning functional nanofillers,although the fabrication and processing remain a great *** this work,a bio-inspired lightweight nano-cellular epoxy/graphene-Fe_(3)O_(4) nanocomposite with high nanofiller loading of 75 wt.%was successfully fabricated by combining features from both nacre and bone structures,via a simple compression molding process together with an eco-friendly supercritical CO_(2) foaming process to achieve robust mechanical strength and excellent electromagnetic interference(EMI)shielding effectiveness(SE)*** aligned graphene-Fe_(3)O_(4) nanoplatelets with well controlled nanoscale porous structures(52.6 nm)enabled both low density(1.26 g/cm^(3))and high specific EMI SE>5200 dB/cm^(2)/g,as well as preserved tensile strength of 67 *** study provides a sustainable route to fabricate nature mimicked structures with high performance and high flexibility for a wide range of applications,from portable electronics to healthcare devices.

关键词： Epoxy foam Layered nano-cellular structures Graphene-Fe_(3)O_(4)nanocomposites Electromagnetic interference shielding

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Flexible,robust,sandwich structure polyimide composite film with alternative MXene and Ag NWs layers for electromagnetic interference shielding

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Journal of Materials Science & Technology 2023年第28期159卷 194-203页

作者： Yu zhang Qiang Gao Xianzhe Sheng Shuai zhang Junjie Chen Yan Ma Jianbin Qin Yongsheng Zhao Xuetao Shi guangcheng zhang Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’anShaanxi 710072China

The design and fabrication of electromagnetic interference shielding films with a novel structure to eliminate undesirable electromagnetic pollution is an important research ***,it is still a challenge to combine and organize nanofillers in different dimensions into the structured network in polymer-based electromagnetic interference(EMI)shielding *** this work,a sandwich struc-ture polyimide(PI)composite film with alternative 2D-MXene network and 1D-Silver nanowires(Ag NWs)network was prepared through the“electrospinning-immersion-hot pressing”*** the increase of Ag NWs content,the EMI shielding effectiveness(SE)gradually increases while maintaining good flexibility and mechanical *** EMI SE and the tensile strength of 150μm thick sand-wich composite film can reach up to 79.54 dB and 39.82 MPa,*** prepared flexible and robust PI composite film with a sandwich structure has high EMI SE with less metal content,which can provide guidelines for the development of high-performance EMI polymeric films with potentials in wearable devices and equipment.

关键词： Electromagnetic interference shielding Sandwich structure composite film Electrospinning Immersion Hot pressing

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Lightweight Dual‑Functional Segregated Nanocomposite Foams for Integrated Infrared Stealth and Absorption‑Dominant Electromagnetic Interference Shielding

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Nano-Micro Letters 2024年第11期16卷 38-55页

作者： Zhonglei Ma Ruochu Jiang Jiayao Jing Songlei Kang Li Ma Kefan zhang Junxian Li Yu zhang Jianbin Qin Shuhuan Yun guangcheng zhang MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary Conditions Shaanxi Key Laboratory of Macromolecular Science and TechnologySchool of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China College of Chemistry and Chemical Engineering Key Laboratory of Auxiliary Chemistry and Technology for Chemical IndustryMinistry of EducationShaanxi University of Science and TechnologyXi’an 710072People’s Republic of China Department of Mechanical and Industrial Engineering University of Toronto5 King’s College RoadTorontoON M5S 3G8Canada Chongqing Innovation Center Northwestern Polytechnical UniversityChongqing 401135People’s Republic of China

Lightweight infrared stealth and absorption-dominant electromagnetic interference(EMI)shielding materials are highly desirable in areas of aerospace,weapons,military and wearable ***,lightweight and high-efficiency dual-functional segregated nanocomposite foams with microcellular structures are developed for integrated infrared stealth and absorption-dominant EMI shielding via the efficient and scalable supercritical CO_(2)(SC-CO_(2))foaming combined with hydrogen bonding assembly and compression molding *** obtained lightweight segregated nanocomposite foams exhibit superior infrared stealth performances benefitting from the synergistic effect of highly effective thermal insulation and low infrared emissivity,and outstanding absorption-dominant EMI shielding performances attributed to the synchronous construction of microcellular structures and segregated ***,the segregated nanocomposite foams present a large radiation temperature reduction of 70.2℃ at the object temperature of 100℃,and a significantly improved EM wave absorptivity/reflectivity(A/R)ratio of 2.15 at an ultralow Ti_(3)C_(2)T_(x) content of 1.7 vol%.Moreover,the segregated nanocomposite foams exhibit outstanding working reliability and stability upon dynamic compression *** results demonstrate that the lightweight and high-efficiency dual-functional segregated nanocomposite foams have excellent potentials for infrared stealth and absorption-dominant EMI shielding applications in aerospace,weapons,military and wearable electronics.

关键词： Segregated nanocomposite foams Microcellular structures Infrared stealth EMI shielding Low infrared emissivity

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Measurement of interstation phase velocity by wavelet transformation

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Earthquake Science 2009年第4期22卷 425-429页

作者： Qingju Wu Xiufen Zheng Jiatie Pan Fengxue zhang guangcheng zhang vInstitute of Geophysics China Earthquake Administration Beijing 100081 China

In this paper, we present wavelet transformation method to measure interstation phase velocity. We use Morlet wavelet function as mother wavelet to filter two seismograms at various period of interest, and correlate the wavelet filtered seismograms to form cross-correlogram. If both wavelet filtered signals are in phase at that period, the phase of the cross-correlogram is a minimum. Using 3-spline interpolation to transform cross-correlation matrix to a phase velocity verse period image, it is convenient for us to measure interstation phase velocity.

关键词： dispesion phase velocity wavelet transform

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Application of Frequency Ratio Method for Landslide Susceptibility Mapping in the Surkhob Valley, Tajikistan

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Journal of Geoscience and Environment Protection 2021年第12期9卷 168-189页

作者： Shakhloi Mukhammadzoda Faizulloev Shohnavaz Oimuhammadzoda Ilhomjon guangcheng zhang Faculty of Geological Engineering China University of Geosciences Wuhan China Institute of Geology Earthquake Engineering and Seismology National Academy of Sciences of Tajikistan Dushanbe Tajikistan

In the valley of the Surkhob River, manifestations of modern geological processes, characterized by various forms of manifestation, are widely developed. Studying these processes is of utmost importance, primarily landslides, which are directly related to the loss of stability of rocks on the slopes. Landslide processes in the Surkhob River valley, regardless of their type, cause significant economic damage to the population and the economy, as well as negatively impacting human living conditions. The primary goal of this project is to map landslide susceptibility using a geographic information system and quantitative and semi-quantitative methods. Landslide susceptibility assessment of this research was conducted using slope (degree), aspect of the slope, curvature, stream power index, topographic wetness index, precipitation and altitude. Except for precipitation, which was collected from the world climate site, most of the causal elements were derived from DEM from the SRTM (Shuttle Radar Topography Mission) database, with cell sizes of 30 m. 416 landslides were discovered from satellite pictures of Google Earth Pro and then validated in the field to analyses the link between causative factors and landslide inventory. To measure the weights of each causal element, the frequency ratio (FR) and the analytical hierarchy process (AHP) were used. The quality of the landslide susceptibility map was determined using the Receiver Operating Characteristics curve (ROC), and the AUC value was determined to be 0.877. It is possible to use the landslide susceptibility map as an engineering and geological basis for establishing a national economic development plan for the territory of the Surkhob River valley.

关键词： Component Formatting Style Styling

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冲击地面过程中落石特征参量的理论分析

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岩石力学与工程学报 2012年第A1期31卷 2839-2846页

作者：章广成唐辉明向欣中国地质大学工程学院湖北武汉430074 中国地质大学教育部长江三峡地质灾害研究中心湖北武汉430074 中国地质大学岩土钻掘与防护教育部工程研究中心湖北武汉430074 中国长江三峡集团公司湖北宜昌443002

根据落石与地面碰撞过程中落石加速度、冲击力的曲线特征,利用动量定理推导正面碰撞时法向冲击力的理论计算公式;在假设切向冲击不影响法向冲击的前提下,提出一种新的摩擦力模型,基于该模型推导切向冲击力和切向恢复系数的理论公式。最... 详细信息

根据落石与地面碰撞过程中落石加速度、冲击力的曲线特征,利用动量定理推导正面碰撞时法向冲击力的理论计算公式;在假设切向冲击不影响法向冲击的前提下,提出一种新的摩擦力模型,基于该模型推导切向冲击力和切向恢复系数的理论公式。最后研究不同入射速度大小、不同入射角时的碰撞时间、恢复系数和最大冲击力的变化规律,分析结果表明:(1)当入射角一定时,随着入射速度增加,冲击力近似呈线性增加,切向恢复系数逐渐增加,但增加幅度很小,而法向碰撞恢复系数和碰撞时间逐渐减小;(2)当入射速度一定时,随着入射角的增加,法向恢复系数和切向恢复系数均增加,但前者增幅远小于后者,碰撞时间也呈增大趋势,而最大冲击力呈先增加后减小的变化规律;(3)地表覆土厚度与落石半径比值越大,碰撞时间越长,法向恢复系数随之递增,切向恢复系数随之递减,而最大冲击力随之呈上凹型曲线递增。

关键词：工程地质正面碰撞斜碰撞恢复系数碰撞时间最大冲击力

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落石碰撞恢复系数的现场试验与数值计算

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岩石力学与工程学报 2011年第6期30卷 1266-1273页

作者：章广成向欣唐辉明中国地质大学工程学院湖北武汉430074 中国地质大学教育部长江三峡库区地质灾害研究中心湖北武汉430074 中国长江三峡集团公司湖北宜昌443002

为研究落石碰撞恢复系数的特征及影响因素,开展野外落石碰撞试验,利用FASTCAM SA1.1高速摄像系统及配套软件Motion Plus解析获得落石碰撞前、后的速度,并求得法向和切向碰撞恢复系数。进而利用ANSYS/LS-DYNA软件对部分试验进行仿真分析... 详细信息

为研究落石碰撞恢复系数的特征及影响因素,开展野外落石碰撞试验,利用FASTCAM SA1.1高速摄像系统及配套软件Motion Plus解析获得落石碰撞前、后的速度,并求得法向和切向碰撞恢复系数。进而利用ANSYS/LS-DYNA软件对部分试验进行仿真分析,数值模拟结果与试验结果吻合较好。研究表明:(1)地面岩土体从基岩、碎屑堆积层至松散碎石土,法向碰撞恢复系数逐渐减小,切向碰撞恢复系数则逐渐增加;(2)法向碰撞恢复系数几乎不受落石边长、入射速度和入射角影响,仅与地面岩土体物理力学性质有关;(3)切向碰撞恢复系数不受落石边长的影响,但随入射速度的增加而递增,随入射角的增加而递减。

关键词：岩石力学碰撞恢复系数高速摄像机 ANSYS/LS-DYNA 屈服应力切线模量

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基于黏弹性接触的落石冲击混凝土棚洞板力学特性理论研究

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岩石力学与工程学报 2023年第3期42卷 606-616页

作者：陈泰江章广成向欣中国地质大学(武汉)工程学院湖北武汉430074 中国长江三峡集团有限公司湖北武汉430010

混凝土棚洞板是防治落石的主要承灾体,现有研究中多将棚洞板简化为梁或薄板单元,以弹性或弹塑性接触理论为基础开展研究,往往低估棚洞板的抗冲击性能。为此,考虑落石与棚洞板接触过程中的阻尼特点,引入等效黏弹性接触理论,将棚洞板视为... 详细信息

混凝土棚洞板是防治落石的主要承灾体,现有研究中多将棚洞板简化为梁或薄板单元,以弹性或弹塑性接触理论为基础开展研究,往往低估棚洞板的抗冲击性能。为此,考虑落石与棚洞板接触过程中的阻尼特点,引入等效黏弹性接触理论,将棚洞板视为正交各向异性板,构建落石冲击棚洞板的力学模型,得到落石冲击棚洞板的动力控制方程,根据落石位移、速度和加速度不同组合初始条件,采用微分方程求解法,推导得到落石冲击棚洞板各特征参量的多种理论解,为验证理论求解的正确性,与数值计算结果进行了对比分析。研究表明:线弹性解只能近似描述落石冲击过程,求解得到的落石各特征参量时程曲线是近似对称的两阶段曲线;而以黏弹性接触模型为基础,速度和加速度组合条件下的落石冲击参量理论解和数值解更相近,能够综合考虑落石冲击棚洞板过程中棚洞板受荷变形以及落石的能量损失,更符合实际工程;落石参数敏感性分析表明,落石最大冲击力、达到最大冲击力的时间以及冲击作用时间和落石质量呈正比,随着落石质量的增大,落石冲击参量显著增加,对棚洞板的损伤更大;对比试验结果以及多种理论计算结果可以得到:所得到的落石冲击力时程规律和试验相接近,而且该理论解给出了直接的函数表达式,有更大的适用范围,能够推广使用。研究成果可为棚洞防护工程设计提供指导。

关键词：岩石力学落石接触理论冲击力冲击时间 ANSYS/LS-DYNA

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电站高温高压蒸汽大管道振动治理

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振动工程学报 2004年第Z2期17卷 1131-1133页

作者：张广成山东电力研究院锅检中心济南250002

电厂运行中的高温高压蒸汽大管道振动具有很大的危害性,往往能造成管道的疲劳损伤和机组的非计划停运,并给运行人员造成巨大的心理压力.利用有限元分析软件CAESAR Ⅱ对管道进行静力学及动力学模态分析,在适当位置增设带间隙和不带间隙... 详细信息

电厂运行中的高温高压蒸汽大管道振动具有很大的危害性,往往能造成管道的疲劳损伤和机组的非计划停运,并给运行人员造成巨大的心理压力.利用有限元分析软件CAESAR Ⅱ对管道进行静力学及动力学模态分析,在适当位置增设带间隙和不带间隙的限位装置,使管系刚度与热应力两者矛盾统一,将管系一阶固有频率提高到2.0 Hz以上,来消减管道的振动.这种方法在山东省内多家电厂都得到了成功应用,取得了令人满意的效果.

关键词：振动管道振动带间隙的限位装置模态分析固有频率

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