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Novel C_(sf)/SiBCN composites prepared by densifying Csf/MA-SiBCN with the PIP process:Oxidation behavior and damage mechanism

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Journal of Advanced Ceramics 2024年第5期13卷 666-678页

作者： Wenhao Dou Daxin Li Bingzhu Wang Zhihua Yang Jun Chen dechang jia Ralf Riedel Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Chongqing Research Institute of HIT Chongqing 401135China Beijing Institute of Control Engineering Beijing 100094China Institut für Materialwissenschaft Technische Universität DarmstadtDarmstadt D-64287Germany School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

To improve the oxidation resistance of short carbon fiber(C_(sf))-reinforced mechanically alloyed SiBCN(MA-SiBCN)(C_(sf)/MA-SiBCN)composites,dense amorphous C_(sf)/SiBCN composites containing both MA-SiBCN and polymer-derived ceramics SiBCN(PDCs-SiBCN)were prepared by repeated polymer infiltration and pyrolysis(PIP)of layered C_(sf)/MA-SiBCN composites at 1100°C,and the oxidation behavior and damage mechanism of the as-prepared C_(sf)/SiBCN at 1300–1600°C were compared and discussed with those of C_(sf)/MA-SiBCN.The C_(sf)/MA-SiBCN composites resist oxidation attack up to 1400°C but fail at 1500°C due to the collapse of the porous framework,while the PIP-densified C_(sf)/SiBCN composites are resistant to static air up to 1600°C.During oxidation,oxygen diffuses through preexisting pores and the pores left by oxidation of carbon fibers and pyrolytic carbon(PyC)to the interior of the matrix.Owing to the oxidative coupling effect of the MA-SiBCN and PDCs-SiBCN matrices,a relatively continuous and dense oxide layer is formed on the sample surface,and the interfacial region between the oxide layer and the matrix of the as-prepared composite contains an amorphous glassy structure mainly consisting of Si and O and an incompletely oxidized but partially crystallized matrix,which is primarily responsible for improving the oxidation resistance.

关键词： mechanically alloyed SiBCN(MA-SiBCN) polymer-derived ceramics SiBCN(PDCs-SiBCN) short carbon fiber-reinforced SiBCN(C_(sf)/SiBCN)composites polymer infiltration and pyrolysis(PIP) oxidation damage mechanism

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Data-driven Reactive Power Optimization of Distribution Networks via Graph Attention Networks

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 874-885页

作者： Wenlong Liao dechang Yang Qi Liu Yixiong jia Chenxi Wang Zhe Yang Wind Engineering and Renewable Energy Laboratory Ecole Polytechnique Federale de Lausanne (EPFL) the College of Information and Electrical Engineering China Agricultural University the College of Electrical Engineering and Automation Shandong University of Science and Technology the Department of Electrical and Electronic Engineering (Energy Digitalization Laboratory) The University of Hong Kong the Department of Electrical Engineering The Hong Kong Polytechnic University

Reactive power optimization of distribution networks is traditionally addressed by physical model based methods, which often lead to locally optimal solutions and require heavy online inference time consumption. To improve the quality of the solution and reduce the inference time burden, this paper proposes a new graph attention networks based method to directly map the complex nonlinear relationship between graphs(topology and power loads) and reactive power scheduling schemes of distribution networks, from a data-driven perspective. The graph attention network is tailored specifically to this problem and incorporates several innovative features such as a self-loop in the adjacency matrix, a customized loss function, and the use of max-pooling layers. Additionally, a rulebased strategy is proposed to adjust infeasible solutions that violate constraints. Simulation results on multiple distribution networks demonstrate that the proposed method outperforms other machine learning based methods in terms of the solution quality and robustness to varying load conditions. Moreover, its online inference time is significantly faster than traditional physical model based methods, particularly for large-scale distribution networks.

关键词： Distribution networks Reactive power Load modeling Transformers Machine learning algorithms Inference algorithms Static VAr compensators

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Unveiling structural features and mechanical properties of amorphous Si_(2)BC_(3)N by density functional theory

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Journal of Materials Science & Technology 2023年第8期139卷 103-112页

作者： Yuchen Liu Yu Zhou dechang jia Zhihua Yang Daxin Li Bin Liu Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Zhejiang Laboratory Hangzhou 311100China

The atomic structural features and the mechanical properties of the Si_(2)BC_(3)N are investigated employ-ing ab-initio calculations.The chemical bonding types and their proportion are clarified.The tetrahedral and trigonal configurations,together with their nesting,are identified,which contribute to the flexibil-ity of structural characteristics.The Si-related coordination aggravates the inhomogeneous distribution of chemical bonding and weakens the tetrahedral units.The accompanying polyhedral distortion is quanti-tatively reflected by the bond length and its deviation of polyhedron units.The elastic moduli and the ideal strengths of Si_(2)BC_(3)N are found to be lower than SiC and Si_(3)N_(4),as a result of the weakening effect of coordination Si on tetrahedral units and the existence of easily distorted trigona.The balance between tetrahedral and trigonal features through composition tailor is believed an effective way for the design of Si-B-C-N ceramics for structural applications.

关键词： Amorphous SiBCN Ab-initio calculations Atomic structure Electronic structure Mechanical properties

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Advanced lanthanide doped upconversion nanomaterials for lasing emission

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Journal of Rare Earths 2022年第5期40卷 687-695,I0001页

作者： Yunfei Shang Tong Chen Tianhui Ma Shuwei Hao Weiqiang Lv dechang jia Chunhui Yang School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001China College of Materials and Chemical Engineering Heilongjiang Institute of TechnologyHarbin 150050China State Key Laboratory of Urban Water Resource and Environment Harbin Institute of TechnologyHarbin 150001China Yangtze Delta Region Institute(Huzhou)&School of Physics University of Electronic Science and Technology of ChinaHuzhou 313001China

Microlasers are narrow-band and coherent light from small cavities,which have been widely applied in biomedicine,optical interconnection,integration devices,etc.Lanthanide doped upconversion materials are potential gain media for microlasers from near infrared(NIR)to visible and UV regimes due to their multi ladder-like metastable energy levels and superior optical frequency conversion capability.The optical feedback from photon scattering of the porous upconversion nanoparticles clusters has been reported to produce upconversion random lasers.The light bouncing back and forth between two reflective surfaces or internal surface has been utilized to achieve modulated upconversion lasing emission.In addition,photon lattices and plasmonic cavities with enhanced electromagnetic fields can amplify the upconversion process within the sub-diffraction volumes and produce highly efficient upconverting lasers.In this review,the recent advances on using lanthanide doped upconversion materials for random,whispering gallery mode(WGM)/Fabry-Perot(FP)cavity and photon lattice/plasmonic cavity modulated upconversion microlasers are overviewed.Current challenges and future directions of the upconverting lasers are also discussed.

关键词： Lanthanide Upconversion Microlaser Microcavity Rare earths

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Simple and scalable synthesis of super-repellent multilayer nanocomposite coating on Mg alloy with mechanochemical robustness,high-temperature endurance and electric protection

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Journal of Magnesium and Alloys 2022年第9期10卷 2446-2459页

作者： Shuqi Wang Yaming Wang Junchen Chen Yongchun Zou jiahu Ouyang dechang jia Yu Zhou Institute for Advanced Ceramics Harbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structure-Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Center of Analysis and Measurement Harbin Institute of TechnologyHarbin 150001China School of New Energy and Materials Southwest Petroleum UniversityChengdu 610500China

Multi-functionalization is the future development direction for protective coatings on metal surface,but has not yet been explored a lot.The effective integration of multiple functions into one material remains a huge challenge.Herein,a superhydrophobic multilayer coating integrated with multidimensional organic-inorganic components is designed on magnesium alloy via one-step plasma-induced thermal field assisted crosslinking deposition(PTCD)processing followed by after-thermal modification.Hard porous MgO ceramic layer and polytetrafluoroethylene(PTFE)nano-particles work as the bottom layer skeleton and filler components separately,forming an organic-inorganic multilayer structure,in which organic nano-particles can be crosslinked and cured to form a compact polymer-like outer layer with hierarchical surface textures.Remarkably,the chemical robustness after prolonged exposure to aqua regia,strong base and simulated seawater solution profits from polymer-like nanocomposite layer uniformly and compactly across the film bulk.Moreover,the self-similar multilayer structure coating endows it attractive functions of strong mechanical robustness(>100th cyclic rotary abrasion),stable and ultra-low friction coefficient(about 0.084),high-temperature endurance,and robust self-cleaning.The organic-inorganic multilayer coating also exhibits high insulating property with breakdown voltage of 1351.8±42.4 V,dielectric strength of 21.4±0.7 V/μm and resistivity of 3.2×10^(10)Ω·cm.The excellent multifunction benefits from ceramic bottom skeleton,the assembly and deposition of multidimensional nano-particles,and the synergistic effect of organic inorganic components.This study paves the way for designing next generation protective coating on magnesium alloy with great potential for multifunctional applications.

关键词： Magnesium alloy Multifunctional multilayer coating Mechanochemical robustness Robust wettability High-temperature endurance

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Composition-dependent structural characteristics and mechanical properties of amorphous SiBCN ceramics by ab-initio calculations

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Journal of Advanced Ceramics 2023年第5期12卷 984-1000页

作者： Yuchen Liu Yu Zhou dechang jia Zhihua Yang Wenjiu Duan Daxin Li Shuzhou Li Ralf Riedel Bin Liu Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China School of Materials Science and Engineering Nanyang Technological UniversitySingapore 639798Singapore Institut für Materialwissenschaft Technische Universität DarmstadtDarmstadt D-64287Germany

The atomic structural features and the mechanical properties of amorphous silicoboron carbonitride ceramics with 13 different compositions in the Si–BN–C phase diagram are investigated employing ab-initio calculations.Both chemical bonds and local structures within the amorphous network relate to the elemental composition.The distribution of nine types of chemical bonds is composition-dependent,where the B–C,Si–N,Si–C,and B–N bonds hold a large proportion for all compositions.Si prefers to be tetrahedrally coordinated,while B and N prefer sp^(2)-like trigonal coordination.In the case of C,the tetrahedral coordination is predominant at relatively low C contents,while the trigonal coordination is found to be the main feature with the increasing C content.Such local structural characteristics greatly influence the mechanical properties of SiBCN ceramics.Among the studied amorphous ceramics,SiB_(2)C_(3)N_(2) and SiB_(3)C_(2)N_(3) with low Si contents and moderate C and/or BN contents have high elastic moduli,high tensile/shear strengths,and good debonding capability.The increment of Si,C,and BN contents on this basis results in the decrease of mechanical properties.The increasing Si content leads to the increment of Si-contained bonds that reduce the bond strength of SiBCN ceramics,while the latter two cases are attributed to the raise of sp^(2)-like trigonal configuration of C and BN.These discoveries are expected to guide the composition-tailored optimization of SiBCN ceramics.

关键词： ultra-high-temperature ceramics density functional theory(DFT) amorphous structure mechanical properties

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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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Enhanced mechanical properties and thermal shock resistance of Si_2BC_3N ceramics with SiC coated MWCNTs

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Journal of Advanced Ceramics 2019年第1期8卷 121-132页

作者： Ning LIAO dechang jia Zhihua YANG Yu ZHOU Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of Technology Key Laboratory of Advanced Structure-Function Integrated Materials and Green Manufacturing Technology Ministry of Industry and Information Technology

Bulk Si_2 BC_3 N ceramics were reinforced with SiC coated multi-walled carbon nanotubes(MWCNTs). The phase compositions, mechanical properties, and thermal shock resistance, as well as the oxidation resistance of the designed Si_2 BC_3 N ceramics were comparatively investigated. The results show that nano SiC coating can be formed on MWCNTs through pyrolyzing polysilazane, which improves the oxidation resistance of MWCNTs. A stronger chemical bonding is formed between the SiC coated MWCNTs and SiC particles, contributing to improved flexural strength(532.1 MPa) and fracture toughness(6.66 MPa m1/2). Besides, the 2 vol% SiC coated MWCNTs reinforced Si_2 BC_3 N ceramics maintains much higher residual strength(193.0 MPa) after thermal shock test at 1000 ℃.The enhanced properties should be attributed to:(1) the breaking of MWCNTs and the debonding between MWCNTs and SiC interfaces, which leads to more energy dissipation;(2) the rough surfaces of SiC coated MWCNTs increase the adhesion strength during the "pull out" of MWCNTs.

关键词： Si2BC3N ceramics SiC coated MWCNTs mechanical properties thermal shock resistance

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Direct ink writing of continuous SiO2 fiber reinforced wave-transparent ceramics

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Journal of Advanced Ceramics 2020年第4期9卷 403-412页

作者： Zhe Zhao Guoxiang Zhou Zhihua Yang Xianqi Cao 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 TechnologyHarbin150080China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China Institute of Petrochemistry Heilongjiang Academy of Science Harbin150001China

This article reports the first example of 3D printed continuous SiO2 fiber reinforced wave-transparent ceramic composites via an adaptation of direct ink writing technology to improve the mechanical and dielectric properties of ceramics.The ceramic inks showed good printability by adding nano-SiO2 powder.The effective continuous fiber-reinforced printing progress was achieved through the design and optimization of the coaxial needle structures by finite element simulation.After printing,the continuous fibers were evenly and continuously distributed in the matrix ceramics and the high molding precision for fiber reinforced composite was kept.It is demonstrated that 10 vol%continuous SiO2 fiber improved the bending strength of ceramics by about 27%better than that of the ceramics without fiber and the dielectric performance has also been greatly improved.The novel method unravels the potential of direct ink writing of continuous fiber reinforced wave-transparent ceramics with complex structures and improved properties.

关键词： 3D printing continuous fiber reinforced rheology dielectric properties

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