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Friction Characteristics of Nanoscale Sliding Contacts between Multi-Asperity Tips and Textured Surfaces

Chinese Journal of Mechanical Engineering 2013年第6期26卷 1109-1117页

作者： TONG Ruiting liu Geng liu tianxiang Shaanxi Engineering Laboratory for Transmissions and Controls Northwestern Polytechnical University

Nanoscale sliding contacts of smooth surfaces or between a single asperity and a smooth surface have been widely investigated by molecular dynamics simulations, while there are few studies on the sliding contacts between two rough surfaces. Actually, the friction of two rough surfaces considering interactions between more asperities should be more realistic. By using multiscale method, friction characteristics of two dimensional nanoscale sliding contacts between rigid multi-asperity tips and elastic textured surfaces are investigated. Four nanoscale textured surfaces with different texture shapes are designed, and six multi-asperity tips composed of cylindrical asperities with different radii are used to slide on the textured surfaces. Friction forces are compared for different tips, and effects of the asperity radii on the friction characteristics are investigated. Average friction forces for all the cases are listed and compared, and effects of texture shapes of the textured surfaces are discussed. The results show that textured surface II has a better structure to reduce friction forces. The multi-asperity tips composed of asperities with R=20r0 （r0=0.227 7 nm） or R=30r0 get higher friction forces compared with other cases, and more atoms of the textured surfaces are taken away by these two tips, which are harmful to reduce friction or wear. For the case of R=10ro, friction forces are also high due to large contact areas, but the sliding processes are stable and few atoms are taken away by the tip. The proposed research considers interactions between more asperities to make the model approach to the real sliding contact problems. The results will help to vary or even control friction characteristics by textured surfaces, or provide references to the design of textured surfaces.

关键词： friction characteristics multi-asperity tips textured surfaces nanoscale sliding contacts multiscale method

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Two Dimensional Nanoscale Reciprocating Sliding Contacts of Textured Surfaces

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 531-538页

作者： TONG Ruiting liu Geng liu tianxiang Shaanxi Engineering Laboratory for Transmissions and Controls Northwestern Polytechnical University Institute for Mechanics and Fluid Dynamics Technische Universit Bergakademie Freiberg

Detailed behaviors of nanoscale textured surfaces during the reciprocating sliding contacts are still unknown although they are widely used in mechanical components to improve tribological characteristics. The current research of sliding contacts of textured surfaces mainly focuses on the experimental studies, while the cost is too high. Molecular dynamics（MD） simulation is widely used in the studies of nanoscale single-pass sliding contacts, but the CPU cost of MD simulation is also too high to simulate the reciprocating sliding contacts. In this paper, employing multiscale method which couples molecular dynamics simulation and finite element method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. Four textured surfaces with different texture shapes are designed, and a rigid cylindrical tip is used to slide on these textured surfaces. For different textured surfaces, average potential energies and average friction forces of the corresponding sliding processes are analyzed. The analyzing results show that ＂running-in＂ stages are different for each texture, and steady friction processes are discovered for textured surfaces II, III and IV. Texture shape and sliding direction play important roles in reciprocating sliding contacts, which influence average friction forces greatly. This research can help to design textured surfaces to improve tribological behaviors in nanoscale reciprocating sliding contacts.

关键词： nanoscale reciprocating sliding contacts textured surface multiscale method

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ANALYSIS ON THERMAL ELASTO-PLASTIC ASPERITY CONTACTS OF LAYERED MEDIA

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Chinese Journal of Mechanical Engineering 2008年第2期21卷 5-12页

作者： TONG Ruiting liu Geng ZENG Quanren liu tianxiang School of Mechatronic Engineering Northwestern Polytechnical University Xi＇an 710072 China

A thermal elasto-plastic asperity contact model is investigated, which takes into account the steady-state heat transfer and the asperity distortion due to thermal elasto-plastic deformations. A hard coating and a soft coating are applied to study the correlations between contact area and contact pressure, average gap and contact pressure, coating thickness and contours of the contact stress distribution, etc. The effects of material properties, coating thickness, frictional coefficient, and the heat input combinations on the stress distribution are investigated and discussed. The frictional heat input increases the maximum value of yon Mises stress. Finally, the appropriate thickness of the hard coating is also discussed. To protect the substrate, one can choose hard coating and the thickness of that is suggested that can be hc=70 Rm.

关键词： Thermal elasto-plastic contact Rough surfaces Coating

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Effect of Particle Conductivity on Fe-Si Composite Electrodeposition

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Chemical Research in Chinese Universities 2014年第5期30卷 811-816页

作者： LONG Qiong ZHONG Yunbo ZHENG tianxiang liu Chunmei Shanghai Key Laboratory of Modern Metallurgy and Materials Processing Shanghai University Shanghai 200072 P R. China

Coatings containing Fe-Si or Si particles were electrodeposited on 3.0%（mass fraction） Si steel sheets. The surface morphology, the cross-section and the silicon content of coating have been investigated, respectively. It was found that the number of particles on the coating surface and cross-section significantly decreased with increasing silicon content in the applied particles, leading to a decrease of the silicon content of coatings. About 10.2% silicon content of coatings deposited with Fe-30%Si particles can be obtained, whereas that for Si particles was only 2.9% at a particle concentration of 100 g/L and current density of 2 A/dm2. This is mainly attributed to the conductivity of applied particles. High conductivity can promote the co-deposition of the particles. With increasing silicon content in the particles, their conductivity decreased sharply, resulting in the decrease of silicon content of coatings. Present work may initiate a new method to modify the particle content of the composite coatings via changing the conductivity of the particles during the composite electrodeposition. In this paper, a possible mechanism was proposed to explain the phenomena.

关键词： Composite electrodeposition Conductivity Fe-Si particle 6.5% Silicon steel

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Recent progress and perspectives on Sb_(2)Se_(3)-based photocathodes for solar hydrogen production via photoelectrochemical water splitting

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Journal of Energy Chemistry 2022年第4期31卷 508-523页

作者： Shuo Chen tianxiang liu Zhuanghao Zheng Muhammad Ishaq Guangxing Liang Ping Fan Tao Chen Jiang Tang Shenzhen Key Laboratory of Advanced Thin Films and Applications Key Laboratory of Optoelectronic Devices and SystemsCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060GuangdongChina Hefei National Laboratory for Physical Sciences at Microscale CAS Key Laboratory of Materials for Energy ConversionDepartment of Materials Science and EngineeringSchool of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026AnhuiChina Wuhan National Laboratory for Optoelectronics(WNLO) School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074HubeiChina

Photoelectrochemical(PEC) cells involved with semiconductor electrodes can simultaneously absorb solar energy and perform chemical reactions, which are considered as an attractive strategy to produce renewable and clean hydrogen energy. Sb_(2)Se_(3) has been widely investigated in constructing PEC photocathodes benefitting of its low toxicity, suitable band gap, superior optoelectronic properties, and outstanding photocorrosion stability. We first present a brief overview of basic concepts and principles of PEC water splitting as well as a comparison between Sb_(2)Se_(3) and other numerous candidates. Then the material characteristics and preparation methods of Sb_(2)Se_(3) are introduced. The development of Sb_(2)Se_(3)-based photocathodes in PEC water splitting with various architectures and engineering efforts(i.e., absorber engineering, interfaces engineering, co-catalyst engineering and tandem engineering) to improve solar-to-hydrogen(STH) efficiency are highlighted. Finally, we debate the possible future directions to further explore the researching fields of Sb_(2)Se_(3)-based photocathodes with a strongly positive outlook in PEC processed solar hydrogen production.

关键词： Sb_(2)Se_(3) Photocathodes Photoelectrochemical Water splitting Solar-to-hydrogen

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Fluxing Agents on Ceramification of Composites of MgO-Al2O3-SiO2/Boron Phenolic Resin

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Journal of Wuhan University of Technology(Materials Science) 2018年第2期33卷 381-388页

作者：石敏先 CHEN Xia FAN Shanshan SHEN Shirley liu tianxiang 黄志雄 School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China CSIRO Manufacturing Gate 5 Normanby Road Clayton VIC 3168 Australia

Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al_2O_3-SiO_2/boron phenol formaldehyde resin（MAS/BPF） composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS/BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS/BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS/BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.

关键词： ceramification boron phenolic resin ceramifiable polymer composite fluxing agent

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东亚民众眼中的中国:中美二元竞争的微观检验

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当代亚太 2024年第1期 54-76,162页

作者：刘天祥中国人民大学国际关系学院

近年来,随着美国在亚太地区的战略布局调整,中美竞争在东亚地区已经成为定势。在此背景下,东亚民众如何看待日益崛起的中国?“亚洲晴雨表”项目在2010~2020年间实施的民意调查为动态检验东亚民众眼中的中国提供了充沛的数据。对三轮调... 详细信息

近年来,随着美国在亚太地区的战略布局调整,中美竞争在东亚地区已经成为定势。在此背景下,东亚民众如何看待日益崛起的中国?“亚洲晴雨表”项目在2010~2020年间实施的民意调查为动态检验东亚民众眼中的中国提供了充沛的数据。对三轮调查数据的动态分析表明,这十年间,中国在东亚地区的影响力总体而言稳步上升,但是民众对此的评价却略趋消极,这体现出东亚民众对中国在东亚地区影响力的关注与担忧。从微观心理层面看,如果民众在政治认知和文化价值观上与中国主流观念的差异加大,则他们对中国的地区影响力的关注更高,评价亦更消极。从宏观国际环境层面看,特朗普就任美国总统及其推出的“印太战略”对东亚地区格局产生了巨大冲击,各国民众对中国影响力的态度也产生了分化。理解影响中国地区影响力的因素,对中国准确把握地区局势发展,在中美竞争背景下进一步扩大自身国际影响力、提高国际形象有着重要的意义。

关键词：东亚民众中美竞争中国影响力民意

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宏观—微观多尺度数值计算方法研究进展

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中国机械工程 2005年第16期16卷 1493-1499页

作者：刘更刘天祥张征沈允文西北工业大学西安710072

主要讨论了三种将连续介质力学和微/纳观理论相结合而发展起来的方法:多尺度连续介质方法、连续介质—分子动力学耦合方法和准连续介质方法。介绍了三种方法的基本思想、基本原理和研究进展。讨论了三类多尺度方法的适用范围,展望了多... 详细信息

主要讨论了三种将连续介质力学和微/纳观理论相结合而发展起来的方法:多尺度连续介质方法、连续介质—分子动力学耦合方法和准连续介质方法。介绍了三种方法的基本思想、基本原理和研究进展。讨论了三类多尺度方法的适用范围,展望了多尺度方法未来的发展趋势。

关键词：微机电系统纳米技术多尺度连续介质力学

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纳米圆柱体与平面粘着接触的分子动力学模拟

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西北工业大学学报 2007年第3期25卷 461-466页

作者：朱世俊刘更刘天祥西北工业大学机电学院陕西西安710072

用分子动力学方法模拟了不同半径的刚性圆柱体压头与弹性基体的粘着接触过程。给出了接触力、静态结构因子及压头与基体最小间隙随压头位移的变化关系,以及接触区域的von Mises应力分布。结果表明,在突跳接触与接触分离时,随着压头尺寸... 详细信息

用分子动力学方法模拟了不同半径的刚性圆柱体压头与弹性基体的粘着接触过程。给出了接触力、静态结构因子及压头与基体最小间隙随压头位移的变化关系,以及接触区域的von Mises应力分布。结果表明,在突跳接触与接触分离时,随着压头尺寸的增大,粘着滞后现象越明显。高应力区出现在接触区域两边,且当压头半径减小时,von Mises应力随着压入深度的增大而迅速增大,说明粘着力对小尺寸压头的接触过程影响较大。

关键词：分子动力学纳米圆柱体粘着接触

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合成六倍体小麦品系籽粒相关性状的QTL定位

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麦类作物学报 2025年第1期45卷 1-15页

作者：孙迎凯李翔刘天相张冰月赵艺清关露露贾亚涛马超沈仲赵力克胡银岗吉万全史学芬白海波王中华西北农林科技大学农学院作物抗逆与高效生产全国重点实验室陕西杨陵712100 鄂尔多斯农牧科学院内蒙古鄂尔多斯017000 宁夏农林科学院农业生物技术研究中心宁夏银川750002

合成六倍体小麦作为一种重要的遗传资源,在籽粒相关性状的研究中起着关键作用。为进一步挖掘合成六倍体小麦籽粒相关性状的数量性状位点(quantitative trait loci,QTL),本研究以西农389与合成六倍体小麦KU2098杂交得到的154个重组自交系... 详细信息

合成六倍体小麦作为一种重要的遗传资源,在籽粒相关性状的研究中起着关键作用。为进一步挖掘合成六倍体小麦籽粒相关性状的数量性状位点(quantitative trait loci,QTL),本研究以西农389与合成六倍体小麦KU2098杂交得到的154个重组自交系(recombinant inbred lines,RIL)群体为材料,用小麦55K SNP芯片构建遗传图谱,对粒长、粒宽、粒面积、粒周长、粒长宽比、千粒重、蛋白质含量、淀粉含量、湿面筋含量共9个籽粒相关性状进行了QTL定位分析。结果表明,在除7B染色体外的20条染色体上共鉴定出84个QTL;这些QTL的LOD值在2.54~39.9之间,解释了0.91%~43.41%表型变异;84个QTL包括31个主要QTL和10个稳定QTL。在1A(1)、1B(1)、1D(1)、2D(1)、4D(1)、5A(1)、5D(1)、6A(2)、6B(2)和7D(1)染色体上共鉴定出12个与籽粒性状相关的QTL簇。在QTL簇C8对应的遗传区间中,筛选到2个有关籽粒性状的基因;在QTL簇C3的遗传区间中,筛选到4个有关品质性状的基因。鉴定出的QTL可为小麦产量和品质改良提供参考。

关键词：合成六倍体小麦小麦55K SNP 籽粒性状 QTLs

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