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Synthesis and property characterization of ternary laminar Zr_(2)SB ceramic

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Journal of Advanced Ceramics 2022年第5期11卷 825-833页

作者： qiqiang zhang Shuai FU Detian WAN Yiwang BAO Qingguo FENG Salvatore GRASSO Chunfeng HU Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Green Building Materials China Building Materials AcademyBeijing 10000China

In this paper,Zr_(2)SB ceramic with purity of 82.95 wt%(containing 8.96 wt%ZrB_(2)and 8.09 wt%zirconium)and high relative density(99.03%)was successfully synthesized from ZrH_(2),sublimated sulfur,and boron powders by spark plasma sintering(SPS)at 1300℃.The reaction process,microstructure,and physical and mechanical properties of Zr_(2)SB ceramic were systematically *** results show that the optimum molar ratio to synthesize Zr_(2)SB is n(ZrH_(2)):n(S):n(B)=1.4:1.6:*** average grain size of Zr_(2)SB is 12.46μm in length and 5.12μm in width,and the mean grain sizes of ZrB2 and zirconium impurities are about 300 *** terms of physical properties,the measured thermal expansion coefficient(TEC)is 7.64×10^(-6) K^(-1) from room temperature to 1200℃,and the thermal capacity and thermal conductivity at room temperature are 0.39 J·g^(-1)·K^(-1)and 12.01 W·m^(-1)·K^(-1),*** room temperature electrical conductivity of Zr_(2)SB ceramic is measured to be 1.74×10^(6)Ω^(-1)·m^(-1).In terms of mechanical properties,Vickers hardness is 9.86±0.63 GPa under 200 N load,and the measured flexural strength,fracture toughness,and compressive strength are 269±12.7 MPa,3.94±0.63 MPa·m1/2,and 2166.74±291.34 MPa,respectively.

关键词： Zr_(2)SB spark plasma sintering(SPS) reaction path microstructure properties

Zr_(2)SeB and Hf_(2)SeB:Two new MAB phase compounds with the Cr_(2)AlC-type MAX phase(211 phase)crystal structures

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Journal of Advanced Ceramics 2022年第11期11卷 1764-1776页

作者： qiqiang zhang Yanchun ZHOU Xingyuan SAN Wenbo LI Yiwang BAO Qingguo FENG Salvatore GRASSO Chunfeng HU Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Hebei Key Lab of Optic–Electronic Information and Materials College of Physics Science and TechnologyHebei UniversityBaoding 071002China State Key Laboratory of Green Building Materials China Building Materials AcademyBeijing 100024China

The ternary or quaternary layered compounds called MAB phases are frequently mentioned recently together with the well-known MAX ***,MAB phases are generally referred to layered transition metal borides,while MAX phases are layered transition metal carbides and nitrides with different types of crystal structure although they share the common nano-laminated structure *** order to prove that MAB phases can share the same type of crystal structure with MAX phases and extend the composition window of MAX phases from carbides and nitrides to borides,two new MAB phase compounds Zr_(2)SeB and Hf_(2)SeB with the Cr_(2)AlC-type MAX phase(211 phase)crystal structure were discovered by a combination of first-principles calculations and experimental verification in this ***-principles calculations predicted the stability and lattice parameters of the two new MAB phase compounds Zr_(2)SeB and Hf_(2)*** they were successfully synthesized by using a thermal explosion method in a spark plasma sintering(SPS)*** crystal structures of Zr_(2)SeB and Hf_(2)SeB were determined by a combination of the X-ray diffraction(XRD),scanning electron microscopy(SEM),and high-resolution transmission electron microscopy(HRTEM).The lattice parameters of Zr_(2)SeB and Hf_(2)SeB are a=3.64398Å,c=12.63223Åand a=3.52280Å,c=12.47804Å,*** the atomic positions are M at 4f(1/3,2/3,0.60288[Zr]or 0.59889[Hf]),Se at 2c(1/3,2/3,1/4),and B at 2a(0,0,0).And the atomic stacking sequences follow those of the Cr_(2)AlC-type MAX *** work opens up the composition window for the MAB phases and MAX phases and will trigger the interests of material scientists and physicists to explore new compounds and properties in this new family of materials.

关键词： Zr_(2)SeB and Hf_(2)SeB MAB phase MAX phase first-principles calculations thermal explosion synthesis

Instrumented oscillographic study on impact toughness of an axle steel DZ2 with different tempering temperatures

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1590-1598页

作者： Shuo Liu Peng zhang Bin Wang Kaizhong Wang Zikuan Xu Fangzhong Hu Xin Bai qiqiang Duan Zhefeng zhang Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Technology Center Ma'anshan Iron and Steel Co.Ltd.Ma'anshan 243000China

Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture *** this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was *** tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of *** toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack *** characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide *** poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface.

关键词： axle steel DZ2 tempering process impact toughness oscillographic impact test impact crack propagation carbides

Wear-resistant Ag-MAX phase 3D interpenetrating-phase composites:Processing,structure,and properties

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Nano Research 2024年第2期17卷 806-819页

作者： Yu Guo Xi Xie Zengqian Liu Longchao Zhuo Jian zhang Shaogang Wang qiqiang Duan Qing Jia Dake Xu Weihai Xue Deli Duan Filippo Berto Zhefeng zhang Rui Yang Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China Electrobiomaterials Institute Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Chemical Engineering Materials and EnvironmentSapienza University of RomeRoma 00185Italy

Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic *** MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact *** biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact ***,a series of bi-continuous Ag-Ti_(3)SiC_(2) MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2) *** mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural *** composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2),and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy *** particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic *** good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2)3D interpenetrating-phase composites appealing for electrical contact applicatio

关键词： three-dimensional(3D)interpenetrating-phase architecture Ag-MAX(M=early transition metal A=element from III or IV main groups and X=carbon or/and nitrogen)phase composites melt infiltration electrical contact materials mechanical

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学术生态与学术可持续发展

科技管理研究 2007年第4期27卷 110-111页

作者：张启强厦门大学公共事务学院福建厦门361005

本文对学术生态以及学术可持续发展现状进行了研究和探讨。学术生态危机是针对目前学术系统存在的问题而提出的新概念。学术界存在的生态危机的实质是学术成果原创性缺乏和学术可持续发展力的软弱。本文建议必须在科学发展观的指导下尽... 详细信息

本文对学术生态以及学术可持续发展现状进行了研究和探讨。学术生态危机是针对目前学术系统存在的问题而提出的新概念。学术界存在的生态危机的实质是学术成果原创性缺乏和学术可持续发展力的软弱。本文建议必须在科学发展观的指导下尽快进行学术系统的生态建设,提高学术主体的创新能力,以促进学术的可持续发展。

关键词：科学发展观学术生态可持续发展

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布坎南国家观述评

东南学术 2006年第5期 41-46页

作者：张启强厦门大学公共事务学院政治学理论专业

布坎南独特的国家观所关注的重点是如何预防政府的危险性并激发国家的潜力。公共选择理论和立宪经济学是布坎南国家观的理论基础。布坎南的国家观包含非常丰富的内涵,立宪民主与立宪改革理论则是其中的一个核心内容。本文简要评述布坎... 详细信息

布坎南独特的国家观所关注的重点是如何预防政府的危险性并激发国家的潜力。公共选择理论和立宪经济学是布坎南国家观的理论基础。布坎南的国家观包含非常丰富的内涵,立宪民主与立宪改革理论则是其中的一个核心内容。本文简要评述布坎南的国家观。

关键词：立宪民主国家公共选择立宪经济学

Fault Detection of Motor Bearing with Embedded coils and PCA Algorithm

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Fault Detection of Motor Bearing with Embedded coils and PCA...

N-doped graphene quantum dot-decorated N-TiO2/P-doped porous hollow g-C_(3)N_(4) nanotube composite photocatalysts for antibiotic photodegradation and H2 production

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作者： Shirong zhang Qin Cheng qiqiang zhang Wenlian Chen Longbo zhang Department of Automation School of Power and Mechanical EngineeringWuhan University Zhejiang Erg Technology Joint Stock Co. Ltd

ISBN: (纸本)9781538629185

Bearing faults are the main contributors to the failures of induction motors,which are widely used in industrial *** this paper,8 embedded coils are firstly proposed for air gap *** the 8 coils,6 differential signals are generated,which are sensitive indicators to the bearing ***,PCA is introduced for fault *** with an oil pump fault detection are carried out to verify our *** results convince the validity and effectiveness of the embedded coils and PCA based method.

关键词： Induction motor Bearing fault PCA algorithm Air gap eccentricity Embedded coils

来源： cnki会议评论

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 165-178页

作者： Jingshu Yuan Yao zhang Xiaoyan zhang Junjie zhang Shen’gen zhang Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Xi’an Fanyi University Xi’an 710105China Shunde Graduate School of University of Science and Technology Beijing Foshan 528399China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao SAR 820000China

Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.

关键词： N-doped TiO_(2) N-doped graphene quantum dots P-doped g-C_(3)N_(4) porous hollow nanotube heterojunction photocatalysis

Reversing free-electron transfer of sulfide cocatalyst for exceptional photocatalytic H_(2)evolution

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Journal of Materials Science & Technology 2024年第4期171卷 147-149页

作者： Yanfeng zhang Zhenyi zhang National Experimental Chemistry Teaching Center Hebei Key Laboratory of Inorganic Nano-materialsCollege of Chemistry and Materials ScienceHebei Normal UniversityShijiazhuang 050024China Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission Key Laboratory of Photosensitive Materials and Devices of Liaoning ProvinceSchool of Physics and Materials EngineeringDalian Minzu UniversityDalian 116600China

Recently,Yu and co-workers deeply explore the potential impact of free electron transfer between co-catalysts and photocatalyst carriers on H_(2)evolution efficiency of active sites over MoS_(2+x).They pro-pose an electron-reversal tactics to evade the unexpected electron transfer and synchronously regulate the above transfer in a beneficial orientation for weakening hydrogen adsorption on S ***,this highlight not only discusses and summarizes the essences of electron reversal and the optimized H ad-sorption/desorption mechanism,but also emphasizes the significance of femtosecond transient absorp-tion spectroscopy(fs-TAS)and in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS)for revealing charge transfer dynamics and *** anticipate that this highlight can disseminate a new per-spective on the roles of photocatalyst carriers in improving cocatalytic H_(2)-production kinetics.

关键词： Photocatalysis Cocatalyst Electron reversal Antibonding-orbital occupancy S–H bonds