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Study on thermal cycling ageing resistance of performances of polypropylene/elastomer/boron nitride nanocomposites for high voltage direct current cable insulation

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High Voltage 2024年第3期9卷 556-565页

作者： Jing Li Yu Gao Zheng Song baixin liu Chenyi Guo Yu Chen Junguo Gao Boxue Du School of Electrical and Information Engineering Tianjin UniversityTianjinChina State Grid Tianjin Chengxi Electric Power Supply Branch TianjinChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbinChina

The influences of thermal cycling ageing on structures and insulation performances of polypropylene(PP)/elastomer/boron nitride(BN)nanocomposites are *** Melt blending method was used to prepare the nanocomposites,in which propylene-based elastomer(PBE)or ethylene-octene copolymer elastomer(EOC)was contained for ***,the samples were treated using a thermal cycling process with a temperature range from-30 to 150℃,and the number of thermal cycles was set from 0 to *** electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry and X-ray diffraction measurements were taken to facilitate the comprehension of structural ***,measurements were taken to assess the trap distribution and direct current(DC)breakdown strength of the *** obtained results revealed that following thermal cycling ageing,the morphology and crystallinity of PP/PBE/BN remained almost *** contrast,PP/EOC/BN exhibited substantial microstructural damage accompanied by a significant reduction in *** the number of thermal cycles increased,the trap level and DC breakdown strength of PP/PBE/BN were maintained at high levels,while those of PP/EOC/BN initially remained stable but then experienced a sharp *** is sug-gested that the addition of BN nanoparticles enhances the thermal cycling ageing resis-tance of the PP/PBE blend,whereas it weakens this resistance of the PP/EOC blend.

关键词： cycling resistance thermal

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First Principles Study of Structural Stability and Magnetic Property of Non-equilibrium Co–Mo Alloys

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Acta Metallurgica Sinica(English Letters) 2014年第6期27卷 1057-1062页

作者： Shunning Li baixin liu Jianbo liu Key Laboratory of Advanced Materials (MOE) School of Materials Science and Engineering Tsinghua University

First principles calculations are carried out to investigate the structural stability of several non-equilibrium intermetallic phases in the cobalt（Co）–Mo system using spin polarized projected augmented-wave potentials. It is revealed that the Co3Mo, CoMo, and CoMo3 alloys are energetically favored to be in D019, B11, and A15 structures, respectively,and that the magnetic moments of Co atoms would decrease rapidly with an increasing percentage of Mo content and would most probably disappear when the content of Mo is no less than 50 at%. Generally, the calculated results in the present work match well with the available experimental observations.

关键词： First principles calculation Transition metals Cobalt Magnetic property Electronic structure

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Different atomic structures observed from ternary Ni-Nb-Ta metallic glasses obtained by ion beam mixing

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Science China(Technological Sciences) 2013年第8期56卷 1842-1846页

作者： WANG YuanYu liu JianBo DAI Ye liu baixin Advanced Materials Laboratory School of Materials Science and EngineeringTsinghua University

Four sets of ternary Ni-Nb-Ta multilayered samples with overall compositions of Ni69Nb8Ta23,Ni55Nb13Ta32,Ni42Nb16Ta42 and Ni29Nb18Ta53,respectively were prepared and subjected to 185 keV xenon ion beam *** experimental results showed that in the four Ni-Nb-Ta multilayered samples,metallic glasses could all be obtained at appropriate doses,supporting the prediction directly from a proven realistic Ni-Nb-Ta interatomic potential through molecular dynamics simulations,and that two different atomic structures were observed,as in the corresponding selected area diffraction patterns,the locations of the diffused bands reflected from the metallic glass phases were observed at different angles for the Ni69Nb8Ta23 and Ni29Nb18Ta53 metallic ***,Voronoi tellessation analysis indicated that the observed difference in atomic structures could be attributed to the distinct coordinate number spectra,i.e.,the spectrum of the Ni69Nb8Ta23 metallic glass has its coordinate number(CN) equal to 13 as dominating atomic configuration(with a weight of about 27%),whereas for the Ni29Nb18Ta53 metallic glass,CN=14 is the dominating atomic configuration(also about 27%).Moreover,the distinct atomic configurations of the obtained Ni-Nb-Ta metallic glasses could be correlated to the structures of the constituent metals of the ternary Ni-Nb-Ta system,as the first neighbor of fcc is 12 and the sum of the first and second neighbors of bcc is 14,implying the structural heredity did play a role in metallic glass formation.

关键词： ion beam mixing molecular dynamics coordinate number structural heredity

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Thermodynamic prediction of metastable phases of Ni-Ti system formed by ion beam mixing

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Science China(Technological Sciences) 2012年第4期55卷 921-926页

作者： ZHAO ShiZhen LI JiaHao liu baixin Advanced Materials Laboratory Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

By taking into account the valence electron number and periodic number of constituting metals, a new method is first proposed to calculate the structural enthalpy in the Miedema's model and the modified Miedema's model is then used to predict the formation of metastable phases in Ni-Ti system. To testify the relevance of the present prediction, the multilayered films of Ni1-xTix (x=27.3, 30.5, 42.4, 83.1, 89) are prepared and irradiated by 200 keV xenon ions. Experiment results reveal that uniform amorphous phases are obtained in the Ni72.7Ti27.3, Ni69.5Ti30.5, and Ni57.6Ti42.4 films by increasing the irradiation dose. While for the Ni16.9Ti83.1 and Ni11Ti89 films, an hcp Ti-based solid solution phase and a bcc Ti-rich solid solution phase coexist upon irradiation dose higher than 6×1014 Xe+/cm2. The predictions of relative stabilities of metastable phases in Ni-Ti system by the modified Miedema's model match well with IBM experiments, thus justifying the modification proposed in the present study.

关键词： metallic glasses thermodynamics multilayer thin film ion-beam processing

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Atomistic simulation study of favored compositions of Ni-Nb-Al metallic glasses

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Science China(Technological Sciences) 2018年第12期61卷 1829-1838页

作者： CAI Bei YANG MengHao liu JianBo LI JiaHao liu baixin Key Laboratory of Advanced Materials(MOE) School of Materials science and Engineering Tsinghua University

This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The simulations not only showed the physical origins of the amorphous phase formation, but also quantitatively predicted a hexagonal compositional region that energetically favors the glass formation. The energy difference between the solid solution and metallic glass, which generates the amorphization driving force(ADF), was suggested to indicate the glass-formation ability(GFA) of each alloy. Based on the computed ADFs, the Ni55 Nb25 Al20 alloy exhibited the highest GFA among the Ni-Nb-Al members, implying that the glass formed by this amorphous alloy is more thermodynamically stable than other alloys in the system. In a Voronoi tessellation analysis, the knee point of the coordination-number distribution curve corresponded to the glass-formation region of the Ni-NbAl system.

关键词： interatomic potential atomistic simulation glass-formation ability Ni-Nb-Al system

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Formation of non-equilibrium phases and associated structural transition in the Pd-Ta system induced by ion beam mixing

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Science China(Technological Sciences) 2011年第3期54卷 676-681页

作者： ZHAO Man DAI Ye LI JiaHao liu baixin Advanced Materials Laboratory Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

For the Pd-Ta system characterized by a negative heat of formation of -78 kJ/mol, 200 keV xenon ion beam mixing with nano-sized Pd-Ta multilayered films was conducted to study the non-equilibrium phase formation. The results showed that uniform amorphous alloys can be formed within a composition range of 25 at%-78 at% Ta, which falls in the maximum possible amorphization range of 22 at%-80 at% Ta predicted by the empirical model. Moreover, two metastable crystalline phases both of FCC structure, yet with different lattice constants were obtained. Interestingly, a self-assembled fractal pattern was observed in the Pd52Ta48 multilayered films after irradiation to a dose of 1×1015 Xe+/cm2 and its dimension was determined to be 1.75±0.05. The possible mechanisms for the formation of amorphous and metastable crystalline phases as well as for the growth of the fractal pattern were discussed.

关键词： amorphous phase Pd-Ta alloy ion beam mixing metastable crystalline phase fractal

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Metallic glass formation in the ternary Ni-Nb-Mo system by ion beam mixing

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Science China(Technological Sciences) 2012年第8期55卷 2206-2211页

作者： LI Yang WANG TongLe DING Ning liu JianBo liu baixin Advanced Materials Laboratory Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Glass forming ability of the ternary Ni-Nb-Mo system was studied by ion beam mixing of the Ni-Nb-Mo multilayered *** the experiment,metallic glasses *** alloys were formed in the Ni51Nb19Mo30,Ni52Nb35Mo13,Ni61Nb15Mo24 and Ni72Nb20Mo8 multilayered films,while only solid solutions were obtained in the Ni24Nb29Mo47 and Ni26Nb53Mo21 multilayered *** turned out that the Ni concentration played a dominating role in affecting the glass-forming ability of the ***,thermodynamic calculations predicted a favored composition region for metallic glass formation,matching well with the observations from ion beam mixing.

关键词： metallic glasses ion beam mixing the Ni-Nb-Mo system

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Structural stability and magnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

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Science China(Technological Sciences) 2009年第9期52卷 2681-2687页

作者： CHE XingLai LI JiaHao DAI Ye liu baixin Advanced Materials Laboratory Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures,i.e. A15,D019,D03 and L12 Ni3Pt and NiPt3,and α-NiAs,B1,B2,L2a,and L10 NiPt. The calculations reveal that the L12 Ni3Pt,L10 NiPt and L12 NiPt3 are energetically more stable than their respective competitive structures,indicating that the three structures may be formed in some appropriate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states,which may significantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds.

关键词： ab initio study magnetism metastable phases

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New fcc Phase Formed in Immiscible Fe-Cu System by Solid State Diffusion

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Chinese Physics Letters 1992年第12期9卷 663-666页

作者： liu baixin PAN Feng TAO Kun Department of Meterials Science and Engineering Tsinghua UniversityBeijing 100084 Center of Condensed Matter and Radiation Physics CCAST(World Laboratory) Beijing 100080

Fe_(75)Cu_(25) nano-multilayers were prepared by alternative deposition of pure Fe and Cu metals and then annealed in situ in transmission electron microscopy to investigate the structural phase transformation.A new phase was formed in the Fe-Cu multilayers by interdiffusion at 820℃ for about I0min and was identified to be of fcc structure with a lattice parameter of 0.854±0.005nm.

关键词： Solid Diffusion annealed

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气候变暖对吉林省降雪量与新增雪深关系的影响

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冰川冻土 2024年第2期46卷 555-564页

作者：于秀晶胡誉瀚石大明胡轶鑫李金泽刘柏鑫姜忠宝吉林省气候中心吉林长春130062 中国民用航空东北地区空中交通管理局吉林分局吉林长春130000

降雪量和积雪深度的关系是降雪预报及水文气候模拟中的重要参数。本文利用吉林省50个站点1961—2021年的降水量、积雪深度、气温、风速和天气现象等气象观测资料,分析了降雪量和新增积雪深度的关系及主要气候影响因子。结果表明,在中等... 详细信息

降雪量和积雪深度的关系是降雪预报及水文气候模拟中的重要参数。本文利用吉林省50个站点1961—2021年的降水量、积雪深度、气温、风速和天气现象等气象观测资料,分析了降雪量和新增积雪深度的关系及主要气候影响因子。结果表明,在中等及以上强度的降雪过程中,吉林省新增积雪深度(D)与降雪量(S)的比值(深量比,Rds)平均为0.96 cm·mm^(-1);该比值存在空间差异,呈西部小东部大的分布特征,且存在明显的月际、年际和年代际变化特征,其中月际变化呈现不对称的抛物线型,12月和1月为大值时段;近60年来Rds呈减小趋势,变化速率为-0.01 cm·mm^(-1)·(10a)^(-1);降雪日Rds与气温呈明显反相关关系,其中在-12~0℃的温度区间,Rds随气温上升呈明显减小趋势。气候变暖、降水量增加和风速的减小是降雪过程中降雪量与新增雪深关系年代际变化的直接原因。揭示降雪量和新增雪深的关系对于认识东北亚中高纬度降雪积雪特征及其成因具有重要意义。

关键词：吉林省降雪量新增雪深深量比时空变化影响因子

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