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Ultrahigh thermal conductive graphite film via the in-situ construction of aligned nanographene skeleton using chemical vapor deposition

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Journal of Materials Science & Technology 2023年第17期148卷 1-9页

作者： Qingliang Shen Qiang Song Caixiang Xiao qiangang Fu Wei li Shouyang Zhang Hejun li Shaanxi Key Laboratory of Fiber Reinforced light Composite Materials State Key Laboratory of Solidification ProcessingNorthwestern Polytechnical UniversityXi’an 710072China

Both high thermal conductivity(K)and large cross-sectional area are essential for thermal dissipation materials to maximize their heat transfer ***,the drastic decrease of K values with the increased thickness makes the existing graphite/graphene films less favored for practical *** this work,graphite film with both large thickness and high K value is produced based on an in-situ com-position strategy between nanographene(G)and pyrocarbon(PyC)via chemical vapor deposition(CVD)using CH_(3) OH/C_(2)H_(5)OH mixed ***’s found that an optimized O/C ratio of precursors facilitates the construction of ordered G skeletons within the deposited G/PyC *** G/PyC compos-ites can be completely graphitized at a lower temperature than the existing *** 2400℃ an-nealing,dense,thick,and highly aligned graphite films were *** K values reach 1350 and 1010 W m^(-1) K^(-1) at the thickness of 40 and 120μm,respectively,surpassing the existing records with similar *** importantly,the proposed method is insensitive to the deposition substrates,and the G/PyC can be infiltrated into large-size fiber preforms as a matrix for preparing centimeter-thick high K ***,the G/PyC also exhibits better mechanical and electromagnetic shielding per-formances than the existing products,indicating a promising multifunctional application prospect.

关键词： Graphene Thermal management Chemical vapor deposition

Two birds with one stone: Simultaneous fabrication of HfC nanowires and CNTs through efficient utilization of polymer-derived ceramics

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Journal of Materials Science & Technology 2022年第34期129卷 163-172页

作者： Yanqin Fu Yulei Zhang Xuemin Yin liyuan Han qiangang Fu Hejun li Ralf Riedel Shaanxi Province Key Laboratory of Fiber Reinforced light Composite Materials Northwestern Polytechnical UniversityXi’an 710072China Technische Universität Darmstadt Institut für MaterialwissenschaftOtto-Berndt-Straβe 3Darmstadt D-64287Germany

Carbon nanotubes(CNTs) are fabricated in carbon cloth by ultilizing the waste gasses when fabricating hafnium carbide nanowires(HfC_(NWS)) through thermal pyrolysis of Hf-containing polymer *** formed HfC_(NWS) are distributed uniformly on the surface of the carbon fibers in carbon/carbon(C/C) composites and display perfect single crystal *** pyrolysis of the Hf-containing organic precursor provides hafnium and carbon source for the growth of HfC_(NWS).The released waste gasses containing CO,CH4and CO_(2)are the main carbon source for the growth of ***,the flexural strength of HfC_(NWS) reinforced carbon/carbon(HfC_(NWS)-C/C) composites is enhanced by ~105% compared with pure C/C,and the CNTs/carbon cloth also displays improved electrochemical performance with respect to capacitor *** present study introduces a novel sustainable and eco-friendly process related to polymer-derived ceramics to form advanced ceramic nanocomposites and proposes a deep understanding of the growth mechanism of CNTs.

关键词： HfC nanowires Carbon nanotubes Waste gasses Effective utilization Polymer-derived ceramics

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孔内微差起爆爆破技术在阿尔塔什工程的应用

水利水电施工 2018年第5期 18-21页

作者：张正勇李振谦李乾刚中国水利水电第五工程局有限公司

孔内分段微差单孔起爆爆破技术能够有效防控爆破有害效应,阿尔塔什大坝工程趾板边坡开挖利用这一技术对新浇筑混凝土进行保护,取得了良好的效果。本文对孔内分段微差单孔起爆爆破技术在阿尔塔什工程中的应用进行详细介绍,其经验可供类... 详细信息

孔内分段微差单孔起爆爆破技术能够有效防控爆破有害效应,阿尔塔什大坝工程趾板边坡开挖利用这一技术对新浇筑混凝土进行保护,取得了良好的效果。本文对孔内分段微差单孔起爆爆破技术在阿尔塔什工程中的应用进行详细介绍,其经验可供类似工程借鉴。

关键词：孔内分段微差爆破保护控制

约束条件对高温差面板混凝土裂缝影响及防治措施

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水利水电施工 2021年第6期 83-87页

作者：张婷婷李乾刚中国水利水电第五工程局有限公司

面板混凝土是典型的超大型薄板结构,长、宽、厚三向尺寸相差悬殊,因初期混凝土受温度变化、自身体积变形引起的收缩、周边约束引起的应力和应变等极易产生收缩性裂缝。而由约束面的约束限制对薄板混凝土产生收缩裂缝基本是全断面的,不... 详细信息

面板混凝土是典型的超大型薄板结构,长、宽、厚三向尺寸相差悬殊,因初期混凝土受温度变化、自身体积变形引起的收缩、周边约束引起的应力和应变等极易产生收缩性裂缝。而由约束面的约束限制对薄板混凝土产生收缩裂缝基本是全断面的,不仅破坏结构的整体性,而且降低混凝土的抗渗耐久性,直接关系到大坝的安全运行。本文结合高温差地区面板混凝土裂缝现状特性进行分析,并对减少混凝土面板约束采取的有效工程防治措施进行说明,供相关人员参考。

关键词：约束条件面板裂縫特性措施

浅谈面板混凝土无轨滑模施工卷扬机选型及布置

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水利水电施工 2021年第6期 75-78页

作者：李乾刚陈洋洋中国水利水电第五工程局有限公司

面板堆石坝的面板采用无轨滑模施工时,必须保证滑模有一定自重,才能抵消混凝土产生的浮托力,因此对卷扬机的选型及布置有较高的要求。阿尔塔什大坝工程面板混凝土采用无轨滑模进行浇筑,通过合理的场地布置及卷扬机选型,保证了面板混凝... 详细信息

面板堆石坝的面板采用无轨滑模施工时,必须保证滑模有一定自重,才能抵消混凝土产生的浮托力,因此对卷扬机的选型及布置有较高的要求。阿尔塔什大坝工程面板混凝土采用无轨滑模进行浇筑,通过合理的场地布置及卷扬机选型,保证了面板混凝土无轨滑模提升处于安全状态。

关键词：面板卷扬机选型布置

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阿尔塔什高面板堆石坝施工技术研究

四川水力发电 2020年第3期39卷 1-6,74页

作者：李振谦李乾刚曹巧玲中国水利水电第五工程局有限公司四川成都610066

阿尔塔什面板堆石坝具有坝体砂砾石填筑体量大,施工工期短、填筑强度高等特点。针对如何高质量、高效率、快速进行面板堆石坝填筑施工这一重大难题,阐述了通过料场开采规划、试验标准的选取、施工参数的选择、施工设备的选型、合理地进... 详细信息

阿尔塔什面板堆石坝具有坝体砂砾石填筑体量大,施工工期短、填筑强度高等特点。针对如何高质量、高效率、快速进行面板堆石坝填筑施工这一重大难题,阐述了通过料场开采规划、试验标准的选取、施工参数的选择、施工设备的选型、合理地进行填筑分期等各项技术手段确保工程各项目标顺利实现的过程,对该高面板堆石坝坝料开采及填筑技术进行了介绍。

关键词：阿尔塔什面板堆石坝开采填筑施工技术

Microstructure and evolution of hafnium carbide whiskers via polymer-derived ceramics:A novel formation mechanism

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Journal of Advanced Ceramics 2023年第3期12卷 578-586页

作者： Yanqin Fu Yulei Zhang Hao Yan Jinhua li Xuemin Yin Jia Sun qiangang Fu Ralf Riedel Shaanxi Key Laboratory of Fiber Reinforced light Composite Materials Northwestern Polytechnical UniversityXi’an 710072China School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an 710021China Institut für Materialwissenschaft Technische Universität DarmstadtDarmstadt D-64287Germany

Polymer-derived ultra-high-temperature ceramic(UHTC)nanocomposites have attracted growing attention due to the increasing demands for advanced thermal structure components in ***,hafnium carbide(HfC)whiskers are successfully fabricated in carbon fiber preforms via the polymer-derived ceramic(PDC)method.A novel carbon nanotube(CNT)template growth mechanism combined with the PDC method is proposed in this work,which is different from the conventional vapor–liquid–solid(VLS)mechanism that is commonly used for polymer-derived nanostructured *** CNTs are synthesized and proved to be the templates for fabricating the HfC whiskers,which are generated by the released low-molecular-weight gas such as CO,CO_(2),and CH4 during the pyrolysis of a Hf-containing *** formed products are composed of inner single crystal HfC whiskers that are measured to be several tens of micrometers in length and 100–200 nm in diameter and outer HfC/HfO_(2)*** work not only proposes a new strategy to prepare the HfC whiskers,but also puts forward a new thinking of the efficient utilization of a UHTC polymer precursor.

关键词： HfC whiskers carbon nanotubes(CNTs) CNT template Hf-containing precursor thermal pyrolysis

Micro/nano multiscale reinforcing strategies toward extreme high-temperature applications:Take carbon/carbon composites and their coatings as the examples

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Journal of Materials Science & Technology 2022年第1期96卷 31-68页

作者： qiangang Fu Pei Zhang Lei Zhuang Lei Zhou Jiaping Zhang Jie Wang Xianghui Hou Ralf Riedel Hejun li State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Fiber Reinforced Light Composite MaterialsCarbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Faculty of Engineering University of NottinghamUniversity ParkNottingham NG72RDUnited Kingdom Institut für Materialwissenschaft Technische Universität DarmstadtOtto-Berndt-Straße 3Darmstadt D-64287Germany

Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior ***,C/Cs are very susceptible to destructive oxidation and thus fail at elevated *** matrix modification and coating technologies with Si-based and ultra-high temperature ceramics(UHTCs)are valid to enhance the oxidation/ablation resistance of C/Cs,it’s not sufficient to satisfy the increasing practical applications,due to the inherent brittleness of ceramics,mismatch issues between coatings and C/C substrates,and the fact that carbonaceous matrices are easily prone to high-temperature *** effectively solve the aforementioned problems,micro/nano multiscale reinforcing strategies have been developed for C/Cs and/or the coatings over the past two decades,to fabricate C/Cs with high strength and excellent high-temperature *** review is to systematically summarize the most recent major and important advancements in some micro/nano multiscale strategies,including nanoparticles,nanowires,carbon nanotubes/fibers,whiskers,graphene,ceramic fibers and hybrid micro/nano structures,for C/Cs and/or the coatings,to achieve high-temperature oxidation/ablation-resistant C/***,this review is concluded with an outlook of major unsolved problems,challenges to be met and future research advice for C/Cs with excellent comprehensive mechanical-thermal ***’s hoped that a better understanding of this review will be of high scientific and industrial interest,since it provides unusual and feasible new ideas to develop potential and practical C/Cs with improved high-temperature mechanical and oxidation/ablation-resistant properties.

关键词： Carbon/carbon composites Micro/nano multiscale reinforcing strategies Oxidation Ablation Erosion Hybrid structures

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阿尔塔什面板堆石坝超长铜止水成型施工技术

水利水电施工 2021年第6期 16-19页

作者：李振谦李乾刚段旺现中国水利水电第五工程局有限公司

新疆阿尔塔什大坝为混凝土面板砂砾石-堆石坝,最大坝高为164.8m,坝体复合高度(地基覆盖+坝高)已达250m级。面板钢止水施工作为混凝土面板堆石坝防渗体系中的关键环节,其施工质量的好坏将直接关系到大坝后期的安全运行。施工过程中铜止... 详细信息

新疆阿尔塔什大坝为混凝土面板砂砾石-堆石坝,最大坝高为164.8m,坝体复合高度(地基覆盖+坝高)已达250m级。面板钢止水施工作为混凝土面板堆石坝防渗体系中的关键环节,其施工质量的好坏将直接关系到大坝后期的安全运行。施工过程中铜止水拖工采用了T2M型铜片滚压成型机和一次冲压成型的整体钢止水接头工艺,既保证施工质量,又提高了施工效率,降低了施工成本,为大坝后续工作开展提供了有利的施工条件。阿尔塔什面板堆石坝钢止水施工技术可供相关工程参考借鉴。

关键词：阿尔塔什面板堆石坝面板铜止水