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Study on the tribological properties of metal rolling bearing under lubrication with diketone lubricants

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Science China(Technological Sciences) 2024年第7期67卷 2003-2017页

作者： DU ShaoNan zhang chenhui LUO Zhi State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Beijing National Laboratory of Molecular Sciences CAS Key Laboratory of Engineering PlasticsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

In this article, 1-(4-ethylphenyl)-nonane-1,3-dione(0206) was prepared by Claisen condensation. By mixing 0206, chelate, and base oil in a ratio of 3.2:4.8:2, a diketone lubricant(PAO=14(20%)) that can achieve superlubricity was prepared and applied to bearing lubrication experiments. The experimental results show that when the bearing was lubricated by base oil, the friction coefficient(COF) and temperature rise decreased with the decrease of the viscosity of PAO. When PAO=14(20%) was used as the lubricant, the COF of the bearing was the lowest(0.001), and the wear morphology was comparable to that of the bearing lubricated with commercial lubricant. Compared with the base oil with the same viscosity, it is found that the COF and temperature rise of the bearing lubricated by PAO=14(20%) were lower under any experimental conditions. And when the amount of lubricant added was 10 μL, the COF of the bearing lubricated by PAO=14(20%) reached a very low value(0.0004).Bearing ball surface analysis identified the formation of diketone adsorption films. Combined with the previous PAO=14(20%)superlubricity mechanism, it was considered that the occurrence of tribochemical reaction and the bearing effect of chelates were the main reasons for the existence of ultra-low friction coefficient and low wear. In addition, when there were polar molecules in the lubricant, they were adsorbed on the metal surface through tribochemical reactions, resulting in many irregular pits on the surface.

关键词： superlubricity diketone chelate tribochemical recations bearing lubrication

Epidemiological and Subtype Characterization of Influenza Viruses Infection in Children in Shenzhen, China during Three Consecutive Seasons (January 2016-December 2018)

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Open Journal of Pediatrics 2024年第5期14卷 851-864页

作者： Yaxian Kuang Ruihong Ma Lei Jia Qiang Yao chenhui zhang Xiaoying Fu Department of Laboratory Medicine Shenzhen Childrens Hospital Affiliated to Shantou University Medical College Shenzhen China The Department of Clinical Laboratory The Sixth Peoples Hospital of Nansha Guangzhou China Guangxi Key Laboratory of Intelligent Precision Medicine Nanning China International Health Medicine Innovation Center Shenzhen University Shenzhen China

Background: Children with seasonal influenza infection cause a significant burden of disease each year in the pediatric clinic. Influenza A and B viruses are the major types responsible for illness. A better understanding of the periodicity facilitates the prevention and control of influenza in children. Objective: This study aims to analyze the epidemiological patterns and subtype characterization of influenza viruses among children in Shenzhen, China. Methods: Influenza samples were collected by nasopharyngeal swabs from influenza like illness patients in Shenzhen Children’s Hospital from January 2016 to December 2018. The positive cases and influenza subtypes were determined by gold labeled antigen detection and reverse transcriptase polymerase chain reaction. The influenza periodicity and age, subtype distribution as well as the association between climate parameters and different influenza subtypes were analyzed by SPSS 22.0. Results: The influenza positive rate during 2016-2018 was 21.0%, with a highest positive rate in the year 2018. The positive rate varied by month, season, and year describing a sequence of peaks presenting primarily in all year including spring, summer and winter. The characteristics of influenza peak were different in each year, with a spring peak in 2016 and a summer plus a winter-spring peaks in 2017 and 2018. In addition, influenza B exhibited a winter-spring seasonal pattern while influenza A displayed a more variable seasonality, highlighting influenza B rather than influenza A which had a negative association with climate parameters. Influenza-positive cases were older than influenza-negative cases (P P Conclusion: Influenza activity in children from Shenzhen typically displays both winter-spring and summer peaks. Influenza A epidemic occurred separately or co-circulated with influenza B, with a winter-spring pattern for influenza B and a much more variable seasonality for influenza A. Influenza B had a negative association with cli

关键词： Influenza Influenza Like Illness Gold Labeled Antigen Detection Reverse Transcriptase Polymerase Chain Reaction Influenza A Influenza B

Buried interface bridging for inverted cesium-formamidinium triiodide perovskite solar cells with long operational stability

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Science China Chemistry 2024年

作者： chenhui zhang Chunjun Liang Fulin Sun Ting Zhu Xinghai Huang Yuzhu Guo Xinyu Guo Kunyang Ge Dan Li Fangtian You Zhiqun He Key Laboratory of Luminescence and Optical Information Ministry of Education Institute of Optoelectronic TechnologyBeijing Jiaotong University Department of Physics School of Physical Science and Engineering Beijing Jiaotong University

In the field of perovskite solar cells(PSCs), the research on defects in the buried interface has been relatively limited due to its non-exposure; however, this interface significantly impacts the performance enhancement of inverted PSCs. This study employs phenylethylammonium chloride(PEACl) molecules as a buffer layer to modify the buried interface of p-i-n structured PSCs,aiming to enhance the uniformity of self-assembled monolayers(SAMs) and facilitate the uniform nucleation and growth of perovskite films on the substrate. Furthermore, the introduction of the PEACl buffer layer effectively passivates defects at the bottom of the perovskite layer and notably enhances the crystal quality of the perovskite film by mitigating residual stress,thereby reducing nonradiative recombination loss. Following these optimizations, the MA-free PSCs treated with PEACl achieve a power conversion efficiency(PCE) of 24.11%, with significant improvements in storage, thermal stability, and operational stability. Particularly noteworthy is the device's performance in an unencapsulated state, whereas after 1,500 hours of continuous light operation stability testing, it retains 97% of its original efficiency. This study not only enriches the systematic understanding of the characteristics of the buried interface in PSCs but also contributes significantly to advancing the commercial production of perovskite photovoltaic technology.

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供应链数字化运营下电力应急物资供应保障体系分析

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A sulfonated modification of PEEK for ultralow friction

中国科技纵横 2024年第1期 138-140页

作者：张晨辉国网河南省电力公司三门峡供电公司河南三门峡 472000

本文对供应链数字化下电力应急物资供应保障体系的建设思路进行研究,旨在设计完善的供应链数字化下的电力应急物资供应保障体系,以期实现更有效的物资供应保障.

关键词：供应链数字化电力应急物资

来源：博看期刊评论

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Friction 2023年第6期11卷 881-893页

作者： Shihua YUAN chenhui zhang State Key Laboratory of Tribology Tsinghua UniversityBeijing100084China

Polyether ether ketone(PEEK)is a widely used material for friction pairs due to its excellent mechanical strength,good wear resistance,and chemical ***,some modifications are necessary when PEEK is used as a water-lubricated friction *** this study,a novel sulfonation method was developed to design a water-lubricated friction pair with ultralow friction,good wear resistance,and high loading *** powders were sulfonated using ClSO3H and sintered to form bulk *** sulfonated PEEK(SPEEK)plastic exhibited good tribological *** a low sliding speed,the friction coefficient was smaller than 0.02 when a 3 wt% NaCl solution was used as the *** order of magnitude of the wear rate was as low as 10^(-8) mm^(3)/(N·m).The mechanism of friction reduction was mainly hydration *** negatively charged -SO_(3)^(-) groups on the friction pair can adsorb hydrated Na+cations by electrostatic *** hydrated Na+cations have a high load capacity and low shearing *** ultralow wear mechanism observed in this study is possibly due to ultralow friction properties of the friction pairs prepared through the proposed sulfonation and thermoforming procedures.

关键词： polyether ether ketone(PEEK) sulfonation hydration lubrication friction wear

Plastic-elastic Model for Water-based Lubrication Considering Surface Force

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 208-218页

作者： Shuowen zhang Mingbo Zhao chenhui zhang State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

Water-based lubrication is an effective method to achieve superlubricity,which implies a friction coefficient in the order of 10−3 or *** numerical,analytical,and experimental studies confirm that the surface force effect is crucial for realizing water-based *** enhance the contribution of the surface force,soft and plastic materials can be utilized as friction pair materials because of their effect in increasing the contact area.A new numerical model of water-based lubrication that considers the surface force between plastic and elastic materials is developed in this study to investigate the effect of plastic flow in water-based *** the complexity of residual stress accumulation in lubrication problems,a simplified plastic model is proposed,which merely calculates the result of the dry contact solution and avoids repeated calculations of the plastic *** results of the two models show good *** deformation reduces the local contact pressure and enhances the function of the surface force,thus resulting in a lower friction coefficient.

关键词： Numerical model Water-based lubrication Mixed lubrication Plastic model Superlubricity

Unlocking the secrets behind liquid superlubricity:A state-ofthe-art review on phenomena and mechanisms

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Friction 2022年第8期10卷 1137-1165页

作者： Tianyi HAN Shuowen zhang chenhui zhang State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

Superlubricity,the state of ultralow friction between two sliding surfaces,has become a frontier subject in ***,a state-of-the-art review of the phenomena and mechanisms of liquid superlubricity are presented based on our ten-year research,to unlock the secrets behind liquid superlubricity,a major approach to achieve *** overview of the discovery of liquid superlubricity materials is presented from five different categories,including water and acid-based solutions,hydrated materials,ionic liquids(ILs),two-dimensional(2D)materials as lubricant additives,and oil-based lubricants,to show the hydrodynamic and hydration contributions to liquid *** review also discusses four methods to further expand superlubricity by solving the challenge of lubricants that have a high load-carrying capacity with a low shear resistance,including enhancing the hydration contribution by strengthening the hydration strength of lubricants,designing friction surfaces with higher negative surface charge densities,simultaneously combining hydration and hydrodynamic contribution,and using 2D materials(e.g.,graphene and black phosphorus)to separate the contact of ***,uniform mechanisms of liquid superlubricity have been summarized for different liquid lubricants at the boundary,mixed,and hydrodynamic lubrication *** the best of our knowledge,almost all the immense progresses of the exciting topic,superlubricity,since the first theoretical prediction in the early 1990s,focus on uniform superlubricity *** review aims to guide the research direction of liquid superlubricity in the future and to further expand liquid superlubricity,whether in a theoretical research or engineering applications,ultimately enabling a sustainable state of ultra-low friction and ultra-low wear as well as transformative improvements in the efficiency of mechanical systems and human bodies.

关键词： liquid superlubricity hydrodynamic lubrication hydration lubrication surface potential surface forces

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能量视角下的电力系统惯量

电力系统自动化 2024年第8期48卷 3-13页

作者：丁磊郭一忱鲍威宇张陈辉王志浩宋国兵山东大学电气工程学院山东省济南市250061 西安交通大学电气工程学院陕西省西安市710049

同步机主导的电力系统中,机械旋转惯量是决定频率动态的主导因素,被代指为系统惯量。随着新能源占比升高,机械旋转惯量不断下降,其主导作用被削弱,现有对电力系统惯量的认知不再适用。文中首先回顾惯量作为阻碍物体状态变化能力度量的... 详细信息

同步机主导的电力系统中,机械旋转惯量是决定频率动态的主导因素,被代指为系统惯量。随着新能源占比升高,机械旋转惯量不断下降,其主导作用被削弱,现有对电力系统惯量的认知不再适用。文中首先回顾惯量作为阻碍物体状态变化能力度量的物理本质,把电力系统建模为包含不同尺度下多种能量形式和元件的能量供应链,将惯量广义化为机械旋转惯量、电惯量、热惯量、流体惯量。能量供应链中,同一尺度上存储惯量和通道惯量组成的“惯量对”决定了该尺度的动态;总的尺度上,不同尺度的多个“惯量对”决定了时域的序贯动态和频域的级联滤波特性。然后,进一步揭示了惯量需求的根源是能量需求,存储单元需要有足够的瞬时可释放能量来应对传输通道引起的能量补充滞后,整个能量供应链需要存储足够的本地能量支撑分散控制。能量视角下的电力系统惯量认知有助于评估新型电力系统的惯量需求,为新型电力系统有功控制的方法设计提供理论指导。

关键词：惯量惯量对电力系统同步机能量供应链多尺度

聚乙烯/碳纤维复合材料的制备及其各向异性传导行为

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复合材料学报 2024年第6期41卷 3053-3059页

作者：石素宇吕建胜张晨辉任智琳许乾坤郑国强河南工程学院材料工程学院郑州450007 郑州大学化工学院郑州450001

各向异性传导高分子复合材料(ACPC)因其独特的各向异性导电、导热等特性在集成电路、传感器件、热管理等领域具有巨大的应用潜力。本文以碳纤维(CF)和高密度聚乙烯(HDPE)膜为原料,碳纤维经高温预处理后,通过超声分散和真空抽滤工艺制备... 详细信息

各向异性传导高分子复合材料(ACPC)因其独特的各向异性导电、导热等特性在集成电路、传感器件、热管理等领域具有巨大的应用潜力。本文以碳纤维(CF)和高密度聚乙烯(HDPE)膜为原料,碳纤维经高温预处理后,通过超声分散和真空抽滤工艺制备三维碳纤维网络,再采用热压成型技术将其与聚乙烯膜复合制备具有各向异性传导行为的HDPE/CF复合材料。通过DSC、SEM、TG及导电性能测试研究了复合材料的微结构、热性质和电性能,采用集成电路和红外热像仪对复合材料的各向异性传导行为进行监测。聚乙烯层与碳纤维网层交替排列且结合紧密;这种交替多层结构赋予了HDPE/CF复合材料层内导电、层间绝缘特性,呈现典型的各向异性传导行为。HDPE/CF复合材料在X方向和Y方向具有优异的导电性能(电导率高达85.71 S/m),高出Z方向5~7个数量级。交替多层结构和碳纤维网的引入显著提高了HDPE/CF复合材料的热稳定性能,其初始热分解温度相对HDPE膜提高了约35℃。该复合材料具有优异的电子载流能力和定向传导能力,在电路连接、定向导电、热管理等领域具有巨大的应用潜力。

关键词：碳纤维高密度聚乙烯各向异性传导导电导热热压成型交替多层结构