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Co-modulated interface binding energy and electric field distribution of layer-structured PVDF–LDPE dielectric composites with BaTiO3: experiment and multiscale simulations

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Frontiers of Materials Science 2023年第3期17卷 155-167页

作者： Ruitian Bo Chunfeng Wang Yongliang Wang peigang he Zhidong Han School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150040China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Engineering Dielectrics and Its Application(Ministry of Education) Harbin University of Science and TechnologyHarbin 150080China

The layer-structured composites were built by the dielectric and insulating layers composed of polyvinylidene fluoride(PVDF)and low-density polyethylene(LDPE)composites containing barium titanate(BT)to modulate the dielectric and energy storage properties of the composites.The simulations on the interface models for molecular dynamics and the geometric models for finite element analysis were performed together with the experimental characterization of the morphology,dielectric,and energy storage properties of the composites.The results revealed that polyethylene as an insulating layer played a successful role in modulating dielectric permittivity and breakdown strength while BT particles exerted positive effects in improving the miscibility between the composed layers and redistributing the electric field.The strong interface binding energy and the similar dielectric permittivity between the PVDF layer and the BT20/LDPE layer made for the layer-structured composites with a characteristic breakdown strength(Eb)of 188.9 kV·mm^(−1),a discharge energy density(Ud)of 1.42 J·cm^(−3),and a dielectric loss factor(tanδ)of 0.017,which were increased by 94%,141%,and decreased by 54%in comparison with those of the BT20/PVDF composite,respectively.

关键词： dielectric composite layer structure low-density polyethylene polyvinylidene fluoride molecular dynamics simulation finite element analysis

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3D-printed Lunar regolith simulant-based geopolymer composites with bio-inspired sandwich architectures

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Journal of Advanced Ceramics 2023年第3期12卷 510-525页

作者： Siqi Ma Yuqi Jiang Shuai Fu peigang he Chengyue Sun Xiaoming Duan Dechang Jia Paolo Colombo Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural–Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Max Planck Institute for Polymer Research Mainz 5512Germany Laboratory for Space Environment and Physical Sciences Harbin Institute of TechnologyHarbin 150001China Department of Industrial Engineering University of PadovaPadova 35122Italy Department of Materials Science and Engineering The Pennsylvania State UniversityPhiladelphia 16802USA

Over time,natural materials have evolved to be lightweight,high-strength,tough,and damage-tolerant due to their unique biological structures.Therefore,combining biological inspiration and structural design would provide traditional materials with a broader range of performance and applications.here,the application of an ink-based three-dimensional(3D)printing strategy to the structural design of a Lunar regolith simulant-based geopolymer(HIT-LRS-1 GP)was first reported,and high-precision carbon fiber/quartz sand-reinforced biomimetic patterns inspired by the cellular sandwich structure of plant stems were fabricated.This study demonstrated how different cellular sandwich structures can balance the structure–property relationship and how to achieve unprecedented damage tolerance for a geopolymer composite.The results presented that components based on these biomimetic architectures exhibited stable non-catastrophic fracture characteristics regardless of the compression direction,and each structure possessed effective damage tolerance and anisotropy of mechanical properties.The results showed that the compressive strengths of honeycomb sandwich patterns,triangular sandwich patterns,wave sandwich patterns,and rectangular sandwich patterns in the Y-axis(Z-axis)direction were 15.6,17.9,11.3,and 20.1 MPa(46.7,26.5,23.8,and 34.4 MPa),respectively,and the maximum fracture strain corresponding to the above four structures could reach 10.2%,6.7%,5.8%,and 5.9%(12.1%,13.7%,13.6%,and 13.9%),respectively.

关键词： Lunar regolith simulant(LRS) three-dimensional(3D)printing geopolymer(GP) in situ resource utilization(ISRU) bio-inspired patterns damage tolerance

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Texture and anisotropy of hot-pressed h-BN matrix composite ceramics with in situ formed YAG

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Journal of Advanced Ceramics 2022年第4期11卷 532-544页

作者： Zhuo ZHANG Xiaoming DUAN Zhuo TIAN Yujin WANG Lan WANG Lei CheN Baofu QIU Delong CAI peigang he Dechang JIA Yu ZHOU Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China

Textured hexagonal boron nitride(h-BN)matrix composite ceramics were prepared by hotpressing using different contents of 3Y_(2)O_(3)–5Al_(2)O_(3)(molar ratio of 3:5)as the sintering additive.During hot-pressing,the liquid Y_(3)Al_(5)O_(12)(YAG)phase showing good wettability to h-BN grains was in situ formed through the reaction between Y_(2)O_(3) and Al_(2)O_(3),and a coherent relationship between h-BN and YAG was observed with[010]_(h-BN)//[111]_(YAG) and(002)_(h-BN)//(321)_(YAG).In the YAG liquid phase environment formed during hot-pressing,plate-like h-BN grains were rotated under the uniaxial sintering pressure and preferentially oriented with their basal surfaces perpendicular to the sintering pressure direction,forming textured microstructures with the c-axis of h-BN grains oriented parallel to the sintering pressure direction,which give these composite ceramics anisotropy in their mechanical and thermal properties.The highest texture degree was found in the specimen with 30 wt%YAG,which also possesses the highest anisotropy degree in thermal conductivity.The aggregation of YAG phase was observed in the specimen with 40 wt%YAG,which resulted in the buckling of h-BN plates and significantly reduced the texture degree.

关键词： hexagonal boron nitride(h-BN) liquid phase sintering texture anisotropy

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Preparation and anisotropic properties of textured structural ceramics: A review

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Journal of Advanced Ceramics 2019年第3期8卷 289-332页

作者： Zhuo ZHANG Xiaoming DUAN Baofu QIU Zhihua YANG Delong CAI peigang he Dechang JIA Yu ZHOU Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin150001China Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China State Key Laboratory of Advanced Welding and Joining Harbin Institute ofTechnologyHarbin Institute of TechnologyHarbin150001China

Ceramics are usually composed of randomly oriented grains and intergranular phases, so their properties are the statistical average along each direction and show isotropy corresponding to the uniform microstructures. Some methods have been developed to achieve directional grain arrangement and preferred orientation growth during ceramic preparation, and then textured ceramics with anisotropic properties are obtained. Texture microstructures give particular properties to ceramics along specific directions, which can effectively expand their application fields. In this review, typical texturing techniques suitable for ceramic materials, such as hot working, magnetic alignment, and templated grain growth(TGG), are discussed. Several typical textured structural ceramics including α-Al2O3 and related nacre bioinspired ceramics, Si3N4 and SiAlON, h-BN, MB2 matrix ultra-high temperature ceramics, MAX phases and their anisotropic properties are presented.

关键词： texture structural ceramics anisotropic properties strengthening and toughening mechanisms

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Microstructural evolution of h-BN matrix composite ceramics with La-Al-Si-O glass phase during hot-pressed sintering

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Journal of Advanced Ceramics 2021年第3期10卷 493-501页

作者： Baofu QIU Xiaoming DUAN Zhuo ZHANG Chen ZHAO Bo NIU peigang he Delong CAI Lei CheN Zhihua YANG Yujin WANG Dechang JIA Yu ZHOU Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

BN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using hexagonal boron nitride(h-BN),lanthanum oxide(La_(2)O_(3)),aluminia(Al_(2)O_(3)),and amorphous silica(SiO_(2))as the raw materials.The effects of sintering temperature on microstructural evolution,bulk density,apparent porosity,and mechanical properties of the h-BN composite ceramics were investigated.The results indicated that La-Al-Si-O liquid phase was formed during sintering process,which provided an environment for the growth of h-BN grains.With increasing sintering temperature,the cristobalite phase precipitation and h-BN grain growth occurred at the same time,which had a significant influence on the densification and mechanical properties of h-BN composite ceramics.The best mechanical properties of BN/La-Al-Si-O composite ceramics were obtained under the sintering temperature of 1700℃.The elastic modulus,flexural strength,and fracture toughness were 80.5 GPa,266.4 MPa,and 3.25 MPa·m^(1/2),respectively.

关键词： h-BN matrix composite ceramics La-A1-Si-O glass phase microstructural evolution nanocrystalline precipitation mechanical properties

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Microstructural evolution and mechanical properties of in situ nano Ta_(4)HfC_(5) reinforced SiBCN composite ceramics

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Journal of Advanced Ceramics 2020年第6期9卷 739-748页

作者： Bingzhu WANG Daxin LI Zhihua YANG Dechang JIA Jingyi GUAN Hao PENG Delong CAI peigang he Xiaoming DUAN Yu ZHOU Tao ZHANG Chenguang GAO Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Beijing Institute of Control Engineering Beijing 100080China

The in situ nano Ta_(4)HfC_(5) reinforced SiBCN-Ta_(4)HfC_(5) composite ceramics were prepared by a combination of two-step mechanical alloying and reactive hot-pressing sintering.The microstructural evolution and mechanical properties of the resulting SiBCN-Ta_(4)HfC_(5) were studied.After the first-step milling of 30 h,the raw materials of TaC and HfC underwent crushing,cold sintering,and short-range interdiffusion to finally obtain the high pure nano Ta_(4)HfC_(5).A hybrid structure of amorphous SiBCN and nano Ta_(4)HfC_(5) was obtained by adopting a second-step ball-milling.After reactive hot-pressing sintering,amorphous SiBCN has crystallized to 3C-SiC,6H-SiC,and turbostratic BN(C)phases and Ta_(4)HfC_(5) retained the form of the nanostructure.With the in situ generations of 2.5 wt% Ta_(4)HfC_(5),Ta_(4)HfC_(5) is preferentially distributed within the turbostratic BN(C);however,as Ta_(4)HfC_(5) content further raised to 10 wt%,it mainly distributed in the grain-boundary of BN(C) and SiC.The introduction of Ta_(4)HfC_(5) nanocrystals can effectively improve the flexural strength and fracture toughness of SiBCN ceramics,reaching to 344.1 MPa and 4.52 MPa·m^(1/2),respectively.This work has solved the problems of uneven distribution of ultra-high temperature phases in the ceramic matrix,which is beneficial to the real applications of SiBCN ceramics.

关键词： Ta_(4)HfC_(5) SiBCN microstructure evolution mechanical properties

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Effects of Fiber Surface Pretreatment and Composite Posttreatment on Mechanical Properties of 2D⁃Cf/Phosphate Geopolymer Matrix Composites

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Journal of Harbin Institute of Technology(New Series) 2020年第3期27卷 233-242页

作者： peigang he Zhanlin Jia Shuai Fu Jiatao Wang Xiaoming Duan Zhihua Yang Dechang Jia Yu Zhou Institute for Advanced Ceramics Department of Materials ScienceHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural⁃Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China

Geopolymers are an important class of materials with potential applications because of their heat resistance,flame resistance,environmental friendliness,and possibilities of being transformed into ceramic matrix composites at low cost.However,the low mechanical properties as well as the intrinsic brittleness limit their technological implementations,and it is necessary to enhance the mechanical properties of geopolymers by adopting various kinds of reinforcements.In this work,therefore,two⁃dimensional continuous carbon fiber(Cf)reinforced phosphate⁃based geopolymer composites(Cf/geopolymer)were prepared through ultrasonic⁃assisted impregnation method.Effects of acetone treatment and high⁃temperature treatment on the properties of Cf/geopolymer composites were studied by X⁃ray photoelectron spectroscopy(XPS),X⁃ray diffraction(XRD),and scanning electron microscopy(SEM).Results of the study proved that acetone treatment plays a key role in ameliorating the interfacial interaction between Cf and phosphate matrix,which can thus enhance the mechanical properties of Cf/geopolymer composites.The Cf/geopolymer composites prepared by acetone⁃treated Cf had a flexural strength of 156.1 MPa and an elastic modulus of 39.7 GPa in Y direction.Moreover,an additional Sol⁃SiO2 re⁃impregnation treatment could further enhance the mechanical properties of the acetone⁃treated Cf/geopolymer composites by repairing the cracks and filling the pores.The results in this paper not only provide insights into the surface modification of Cf,but also report a facile and low⁃cost preparation route for Cf/geopolymer composites with potential applications in aerospace and defense technology.

关键词： geopolymer carbon fiber composite surface modification mechanical properties

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Effects of Zr and chopped C fiber on microstructure and mechanical properties of SiBCN ceramics

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Science China(Technological Sciences) 2020年第8期63卷 1520-1530页

作者： ZHU QiShuai WANG GaoYuan LIAO XingQi LI DaXin YANG ZhiHua JIA DeChang DUAN XiaoMing he peigang ZHOU Yu Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structure-Function Integrated Materials and Green Manufacturing Technology Ministry of Industry and Information TechnologyHarbin 150080China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150080China

To further improve the thermal shock resistance and ablation resistance of SiBCN system ceramics targeted much harsh environment,both ultra-high temperature ceramic phases and carbon fibers are expected to be incorporated simultaneously as the reinforcements.However,tough problems like difficulty in densification as well as degradation of C fibers(Cf)due to interfacial reaction usually cannot be avoided.Thus,in this study,Zr as well as chopped Cf with BN coating were introduced into SiBCN ceramics by mechanical alloying and after hot-pressing sintering to prepare Cf/SiBCNZr composites.The structure and phase component development have been characterized in detail by XRD,SEM,TEM and XPS etc.,and mechanical properties,fracture behavior and toughening mechanisms were also investigated.Zr-B and Zr-O bonds are detected besides Si-C,N-B and N-B-C bonds when pre-alloyed ZrB2 amorphous powder was incorporated into SiBCN system by further mechanical-alloying treatment.After hot-pressing,the ultra-high temperature phases of ZrB2 and ZrN were formed as expected besides the original matrix phases of BN(C)and SiC.Excellent mechanical properties can be obtained for SiBCNZr ceramic.The BN coating on carbon fibers successfully avoids the severe fiber degradation and makes it possible for moderating strong interface bonding,which ensuring the debonding,crack deflection,fiber pulling-out and bridging during the fracture.As a result,the Cf/SiBCNZr composites retain good mechanical properties and fractures in a pseudoplastic fracture manner,showing better potential applications in harsh environments.Optimization of the BN coating on Cf and Zr incorporation by pre-mechanical alloying can be a good route to achieve Cf/SiBCNZr composites with a better balance between thermal shock resistance,ablation resistance and mechanical properties.

关键词： SiBCN ZrB2 ZrN carbon fiber BN coating chemical bond microstructure mechanical properties fracture toughening

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航空渗碳齿轮钢的迭代发展

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航空材料学报 2023年第1期43卷 60-69页

作者：郑医何培刚李宁孙振淋中国航发哈尔滨东安发动机有限公司哈尔滨150066 哈尔滨工业大学材料科学与工程学院哈尔滨150001

对航空动力传动系统渗碳齿轮材料的代际发展、组分特征与强化机制进行综述。第一代渗碳齿轮钢为低碳中低合金钢,渗层组织通过Fe_(3)C型碳化物进行表面硬化,因合金化元素含量低,第一代渗碳齿轮钢回火抗力差,普遍服役温区≤200℃。在第一... 详细信息

对航空动力传动系统渗碳齿轮材料的代际发展、组分特征与强化机制进行综述。第一代渗碳齿轮钢为低碳中低合金钢,渗层组织通过Fe_(3)C型碳化物进行表面硬化,因合金化元素含量低,第一代渗碳齿轮钢回火抗力差,普遍服役温区≤200℃。在第一代渗碳齿轮钢中,16Cr3NiWMoVNbE材料碳化物形成元素含量相对较高,通过临界饱和渗碳工艺方法,该材料可进阶为第二代渗碳齿轮钢进行宽温域服役。第二代渗碳齿轮钢为低碳中高合金钢,通过进一步提高合金化程度,适当提升抗回火能力较强的Mo元素含量,基体回火时,可析出部分回火抗力较高的M_(2)C强化相,整体服役温区提升至≤350℃。第三代渗碳齿轮钢为低碳超高合金钢,借助计算材料学,充分发挥出“二次硬化”强化基体效果,能够在500℃以下温区长期服役。现有合金结构钢体系的强化机制,无法避免500℃以上高温长期服役的强度快速衰减问题,下一代渗碳齿轮材料,将以抗氧化性能优异的铁基合金为基础进行研制。

关键词：齿轮钢渗碳二次硬化沉淀硬化

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Improvement of Ga_(2)O_(3)vertical Schottky barrier diode by constructing NiO/Ga_(2)O_(3)heterojunction

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Journal of Semiconductors 2024年第4期45卷 63-68页

作者： Xueqiang Ji Jinjin Wang Song Qi Yijie Liang Shengrun Hu Haochen Zheng Sai Zhang Jianying Yue Xiaohui Qi Shan Li Zeng Liu Lei Shu Weihua Tang peigang Li School of Integrated Circuits&State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China College of Integrated Circuit Science and Engineering Nanjing University of Posts and TelecommunicationsNanjing 210023China Beijing Microelectronics Technology Institute Beijing 100076China

The high critical electric field strength of Ga_(2)O_(3)enables higher operating voltages and reduced switching losses in power electronic devices.Suitable Schottky metals and epitaxial films are essential for further enhancing device performance.In this work,the fabrication of vertical Ga_(2)O_(3)barrier diodes with three different barrier metals was carried out on an n--Ga_(2)O_(3)homogeneous epitaxial film deposited on an n+-β-Ga_(2)O_(3)substrate by metal-organic chemical vapor deposition,excluding the use of edge terminals.The ideal factor,barrier height,specific on-resistance,and breakdown voltage characteristics of all devices were investigated at room temperature.In addition,the vertical Ga_(2)O_(3)barrier diodes achieve a higher breakdown volt-age and exhibit a reverse leakage as low as 4.82×10^(-8)A/cm^(2)by constructing a NiO/Ga_(2)O_(3)heterojunction.Therefore,Ga_(2)O_(3)power detailed investigations into Schottky barrier metal and NiO/Ga_(2)O_(3)heterojunction of Ga_(2)O_(3)homogeneous epitaxial films are of great research potential in high-efficiency,high-power,and high-reliability applications.

关键词： Ga_(2)O_(3) Schottky barrier diode NiO/Ga_(2)O_(3)heterojunction

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