检索结果-南通市图书馆

Low-temperature densification of high-entropy(Ti,Zr,Nb,Ta,Mo)C-Co composites with high hardness and high toughness

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2022年第5期11卷 805-813页

作者： Si-Chun LUO wei-ming guo Kevin PLUCKNETT Hua-Tay LIN School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China School of Mechanical and Electronic Engineering Pingxiang UniversityPingxiang 337000China Department of Process Engineering and Applied Science Dalhousie UniversityHalifax B3J1ZICanada

In order to prepare high toughness(Ti,Zr,Nb,Ta,Mo)C ceramics at low temperatures while maintaining high hardness,a liquid-phase sintering process combined with Co-based liquid-phase extrusion strategy was adopted in this *** densification temperature can be lowered to 1350℃,which is much lower than the solid-state sintering temperature(~2000℃)generally employed for high-entropy carbide *** sintered at 1550℃and 30 MPa applied pressure,part of the Co-based liquid-phase was squeezed out of the graphite mold,such that only~3.21 vol%of Co remained in the high-entropy *** to the Co-free solid-state sintered(Ti,Zr,Nb,Ta,Mo)C ceramics,prepared at 2000℃and 35 MPa,the hardness was slightly decreased from 25.06±0.32 to 24.11±0.75 GPa,but the toughness was increased from 2.25±0.22 to 4.07±0.13 MPa·m^(1/2).This work provides a new strategy for low-temperature densification of high-entropy carbides with both high hardness and high toughness.

关键词： high-entropy carbide ceramics liquid-phase sintering microstructure grain size mechanical properties

Optimal preparation of high-entropy boride-silicon carbide ceramics

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2021年第1期10卷 173-180页

作者： Yan ZHANG Shi-Kuan SUN wei-ming guo Liang XU wei ZHANG Hua-Tay LIN School of Electron-mechanical Engineering Guangdong University of TechnologyGuangzhou 510006China Department of Materials Science and Engineering University of SheffieldSheffield SI 3JDUK

High-entropy boride-silicon carbide(HEB-SiC)ceramics were fabricated using boridebased powders prepared from borothermal and boro/carbothermal reduction *** effects of processing routes(borothermal reduction and boro/carbothermal reduction)on the HEB powders were ***-SiC ceramics with>98%theoretical density were prepared by spark plasma sintering at 2000℃.It was demonstrated that the addition of SiC led to slight coarsening of the *** HEB-SiC ceramics prepared from boro/carbothermal reduction powders showed a fine-grained microstructure and higher Vickers9 hardness but lower fracture toughness value as compared with the same composition prepared from borothermal reduction *** results indicated that the selection of the powder processing method and the addition of SiC phase could contribute to the optimal preparation of high-entropy boride-based ceramics.

关键词： high-entropy boride-silicon ceramics borothermal reduction boro/carbothermal reduction microstructure mechanical properties

Design strategy of phase and microstructure of Si_(3)N_(4) ceramics with simultaneously high hardness and toughness

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2023年第1期12卷 122-131页

作者： Shao-Jun TANG wei-ming guo Shi-Kuan SUN Hua-Tay LIN School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China School of Material Science and Energy Engineering Foshan UniversityFoshan 528000China

Aiming to achieve silicon nitride( Si_(3)N_(4))ceramics with high hardness and high toughness,the relationships among phase composition,microstructure,and mechanical properties of Si_(3)N_(4) ceramics prepared by spark plasma sintering(SPS)at temperatures ranging from 1500 to 1800℃were investigated in this *** stages with different phase and microstructure features were observed and ***α-βphase transformation occurs first,and the development and growth of grains lag *** the first stage,the average grain size remains basically unchanged,and the hardness maintains at a value of~20.18±0.26 GPa,despite theβ- Si_(3)N_(4) phase fraction increases from 7.67 to 57.34 wt%.Subsequently,the equiaxed grains transform into rod-like grains with a high aspect ratio via the reprecipitation process,resulting in a significant increase in the fracture toughness from 3.36±0.62 to 7.11±0.15 MPa·m^(1/2).In the second stage of sintering process,the fraction ofβ- Si_(3)N_(4) phase increases to 100.00 wt%,and the grain growth also rapidly ***,the fracture toughness increases slightly to 7.61±0.42 MPa·m^(1/2),but the hardness reduces to 16.80±0.20 *** current results demonstrate that the phase contents ofβ- Si_(3)N_(4) and the microstructure shall be carefully tailored to achieve high-performance Si_(3)N_(4) ceramics. Si_(3)N_(4) ceramics with a finegrained bimodal microstructure,consisting of the mainα-andβ-phases,can exhibit the optimized combination of hardness and toughness.

关键词： silicon nitride(Si_(3)N_(4)) phase composition microstructure hardness toughness

Textured and toughened high-entropy(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C-SiCw ceramics

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第35期94卷 99-103页

作者： Si-Chun Luo wei-ming guo Yu-Zhang Zhou Kevin Plucknett Hua-Tay Lin School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China College of Mechanical and Electronic Engineering Pingxiang UniversityPingxiang337000China Department of Process Engineering and Applied Science Dalhousie UniversityHalifax B3J 1Z1Canada

High-entropy(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C ceramics,with different contents(0,5,10,and 20 vol.%)of Si C whiskers(SiCw),were fabricated by spark plasma sintering using raw powders synthesized via carbothermal *** application of a uniaxial compaction force led to texture development of the SiCw within the(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C *** toughness increased with the increase in SiCw content,while Vickers hardness remains almost *** toughness of(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C-20 vol.%SiCw ceramics reached 4.3±0.3 MPa m^(1/2),which was approximately 43%higher than that of the monolithic(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C ceramic(3.0±0.2 MPa m1/2).The main toughening mechanisms were attributed to crack deflection,whisker debonding,and whisker pullout.

关键词： High-entropy carbide ceramics Silican carbide whiskers Microstructure Mechanical properties Toughening mechanism

Hot deformation mechanism and microstructure evolution of an ultra-high nitrogen austenitic steel containing Nb and V

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1043-1049页

作者： Rong-hua Zhang Ze-an Zhou ming-wei guo Jian-jun Qi Shu-hua Sun Wan-tang Fu State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Metallurgy and Energy Hebei United University

The flow curves of an ultra-high nitrogen austenitic steel containing niobium(Nb) and vanadium(V) were obtained by hot compression deformation at temperatures ranging from 1000°C to 1200°C and strain rates ranging from 0.001 s-1 to 10 s-1. The mechanical behavior during hot deformation was discussed on the basis of flow curves and hot processing maps. The microstructures were analyzed via scanning electron microscopy and electron backscatter diffraction. The relationship between deformation conditions and grain size after dynamic recrystallization was obtained. The results show that the flow stress and peak strain both increase with decreasing temperature and increasing strain rate. The hot deformation activation energy is approximately 631 k J/mol, and a hot deformation equation is proposed.(Nb,V)N precipitates with either round, square, or irregular shapes are observed at the grain boundaries and in the matrix after deformation. According to the discussion, the hot working should be processed in the temperature range of 1050°C to 1150°C and in the strain rate range of 0.01 to 1 s-1.

关键词： austenitic steels hot deformation microstructural

Fabrication and modelling of Si_(3)N_(4)ceramics with radial grain alignment generated through centripetal sinter-forging

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第31期126卷 1-14页

作者： Da-Wang Tan Zhen-Yong Lao wei-ming guo Akira Kondo Takahiro Kozawa Makio Naito Kevin Plucknett Hua-Tay Lin Department of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China Joining and Welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka 567-0047Japan Department of Mechanical Engineering Dalhousie UniversityHalifaxNova Scotia B3H 4R2Canada

Silicon nitride(Si_(3)N_(4))based ceramics are one of the most attractive advanced engineering materials,which have been widely used under high-speed rotational operation or for mechanical contacts across a curved *** the present study,rotationally symmetric texturing of Si_(3)N_(4),with radial grain align-ment,was obtained by centripetal sinter-forging(CSF)of a partially sintered *** average values of the included angles between the c-axis of the local Si_(3)N_(4)grain and radial direction were approxi-mately 16.4°and 11.0°,on the section plane perpendicular to the pressing direction,and parallel to both the pressing and radial directions,*** compressive strain in the pressing direction forced the ceramic body to flow towards the central axis,resulting in compressive strain in the tangential di-rection and tensile strain in the radial direction.A fundamental physical model was created to simulate the grain rotation during the 3-dimentional strain reorientation,which revealed the rod-like grain would preferentially rotate toward the center of the sample under the CSF *** addition,due to the fric-tion between the sample surface and the pressing punch,the increased shear strain could enhance the Si_(3)N_(4)grain ***,ceramics with rod-like grains perpendicular to the curved side sur-face could be anticipated by applying the centripetal forming concept in a controlled manner.

关键词： Si_(3)N_(4)ceramic Texture Radial grain alignment Modeling CSF

Phase and CCT Diagram of an N-Containing 8%Cr Roller Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2013年第6期20卷 112-117页

作者： Shu-Hua Sun Bo Wang Zhen-Hua Wang Yang Gao ming-wei guo Wan-Tang Fu State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Sciences Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science (Yanshan University) Ministry of Education of China China First Heavy Industries

The pseudo-equilibrium phase diagram and continuous cooling transformation diagram of an N-containing 8％ Cr roller steel were investigated by using thermodynamic calculation,differential scanning calorimetry,Ⅹ-ray diffraction,expansion method,and so *** equilibrium conditions,the main carbonitrides are MX,M7C3,and M23C6 *** measured Ac1,Ac3,start temperature of martensitic transformation,and M7C3 transformation temperatures are 811,855,324,and 1100 ℃,*** appears at cooling rates ranging from 0.5 to 5 ℃/s and ferrite forms at grain boundaries at a cooling rate lower than 0.5 ℃/***,the effects of adding N and lowering the C content on workability and mechanical properties of common 8％Cr steel were discussed.

关键词： high Cr roller steel phase diagram continuous cooling transformation N alloyingCLC number:TG142.45 Document code:AArticle ID:1005-9113(2013)06-0112-06

A Deep Learning Method for Computing Eigenvalues of the Fractional Schrödinger Operator

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第2期37卷 391-412页

作者： guo Yixiao ming Pingbing LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

The authors present a novel deep learning method for computing eigenvalues of the fractional Schrödinger *** proposed approach combines a newly developed loss function with an innovative neural network architecture that incorporates prior knowledge of the *** improvements enable the proposed method to handle both high-dimensional problems and problems posed on irregular bounded *** authors successfully compute up to the first 30 eigenvalues for various fractional Schrödinger *** an application,the authors share a conjecture to the fractional order isospectral problem that has not yet been studied.

关键词： Eigenvalue problem deep learning fractional Schrödinger operator isospectral problem

Wellbore-heat-transfer-model-based optimization and control for cooling downhole drilling fluid

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 1955-1968页

作者： Chao Wang He Liu guo-wei Yu Chen Yu Xian-ming Liu Peng Huang Yangtze University Jingzhou434023HubeiChina State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing2249China CNPC Bohai Drilling Engineering Co. LtdTianjin300280China Exploration Development and Construction Engineering Division of PetroChina Jidong Oilfield Company Tangshan63200HebeiChin Henan University of Urban Construction Pingdingshan467036HenanChina

To address the two critical issues of evaluating the necessity of implementing cooling techniques and achieving real-time temperature control of drilling fluids underground in the current drilling fluid cooling technology,we first established a temperature and pressure coupled downhole heat transfer model,which can be used in both water-based and oil-based drilling ***,fourteen factors,which could affect wellbore temperature,were *** on the standard deviation of the downhole temperature corresponding to each influencing factor,the influence of each factor was *** influencing factors that can be used to guide the drilling fluid's cooling technology were drilling fluid thermal conductivity,drilling fluid heat capacity,drilling fluid density,drill strings rotation speed,pump rate,viscosity,ROP,and injection *** nondominated sorting genetic algorithm was used to optimize these six parameters,but the optimization process took 182 *** these eight parameters'influence rules with the nondominated sorting genetic algorithm can reduce the optimization time to 108 ***,the downhole temperature has been demonstrated to increase with the inlet temperature increasing linearly under quasi-steady *** this law and PID,the downhole temperature can be controlled,which can reduce the energy for cooling the surface drilling fluid and can ensure the downhole temperature reaches the set value as soon as possible.

关键词： Drilling Cooling Influencing factors Analysis Optimization Control