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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 studied.The results show that the optimum molar ratio to synthesize Zr_(2)SB is n(ZrH_(2)):n(S):n(B)=1.4:1.6:0.7.The 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 nm.In 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),respectively.The 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

Electron-irradiation-facilitated production of chemically homogenized nanotwins in nanolaminated carbides

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Journal of Advanced Ceramics 2023年第6期12卷 1288-1297页

作者： hui Zhang Qianqian Jin Tao hu Xiaochun Liu Zezhong Zhang chunfeng hu Yanchun Zhou Yu Han Xiaohui Wang Electron Microscopy Center South China University of TechnologyGuangzhou 510640China School of Emergent Sof Mater South China University of TechnologyGuangzhou 510640China Center for the Structure of Advanced Matter School of Electronic EngineeringGuangxi University of Science and TechnologyLiuzhou 545006China Institute of Materials Science and Devices School of Materials Science and EngineeringSuzhou University of Science and TechnologySuzhou 215009China Institute of Metals Changsha University of Science&TechnologyChangsha 410004China Electron Microscopy for Materials Research(EMAT) University of AntwerpAntwerp 2020Belgium Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China School of Materials Science&Engineering Zhengzhou UniversityZhengzhou 4501China Advanced Membranes and Porous Materials Center Physical Sciences and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Twin boundaries have been exploited to stabilize ultrafine grains and improve mechanical properties of nanomaterials.The production of the twin boundaries and nanotwins is however prohibitively challenging in carbide ceramics.Using a scanning transmission electron microscope as a unique platform for atomic-scale structure engineering,we demonstrate that twin platelets could be produced in carbides by engineering antisite defects.The antisite defects at metal sites in various layered ternary carbides are collectively and controllably generated,and the metal elements are homogenized by electron irradiation,which transforms a twin-like lamellae into nanotwin platelets.Accompanying chemical homogenization,α-Ti_(3)AlC_(2) transforms to unconventionalβ-Ti_(3)AiC_(2).The chemical homogeneity and the width of the twin platelets can be tuned by dose and energy of bombarding electrons.Chemically homogenized nanotwins can boost hardness by~45%.Our results provide a new way to produce ultrathin(<5 nm)nanotwin platelets in scientifically and technologically important carbide materials and showcase feasibility of defect engineering by an angstrom-sized electron probe.

关键词： electron-irradiation MAX phases carbides antisite defects crystal-structure engineering

Hot forging Nb_(4)AlC_(3)ceramics with enhanced properties

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Journal of Advanced Ceramics 2023年第11期12卷 2032-2040页

作者： Ye Yu Shuai Fu Detian Wan Yiwang Bao Longsheng Chu Qingguo Feng 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 100024China

Textured Nb_(4)AlC_(3)ceramics were rapidly and efficiently prepared by hot forging through spark plasma sintering(SPS).The longitudinal compression ratio of textured Nb_(4)AlC_(3)ceramics was−78.3%,and the lateral expansion ratio was 32.1%.The grains grew preferentially along the direction perpendicular to the c-axis,forming the texture microstructure.The Lotgering orientation factor f(00l)was calculated to be 0.63.The thermal conductivity of textured Nb_(4)AlC_(3)ceramics along the c-axis direction(11.23 W·m^(−1)·K^(−1))(25℃)was lower than that of untextured ceramics(13.75 W·m^(−1)·K^(−1))(25℃).The electrical conductivity perpendicular to the c-axis direction reached 4.37×10^(6) S·m^(−1)at room temperature.The ordered layered grains increased the resistance of crack propagation,resulting in a higher fracture toughness parallel to the c-axis direction(9.41 MPa·m^(1/2)),which was higher than that of untextured ceramics(6.88 MPa·m1/2).The Vickers hardness tested at 10 N on the texture top surface(7.18 GPa)was higher than that on the texture side surface(6.45 GPa).

关键词： Nb_(4)AlC_(3) texture anisotropy 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 phases.However,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 characteristics.In 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 work.First-principles calculations predicted the stability and lattice parameters of the two new MAB phase compounds Zr_(2)SeB and Hf_(2)SeB.Then they were successfully synthesized by using a thermal explosion method in a spark plasma sintering(SPS)furnace.The 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,respectively.And 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 phases.This 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

Effect of potential difference between nano-Al_(2)O_(3)whisker and Mg matrix on the dispersion of Mg composites

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International Journal of Minerals,Metallurgy and Materials 2023年第1期30卷 104-111页

作者： Xiaoying Qian Hong Yang chunfeng hu Ying Zeng Yuanding huang Xin Shang Yangjie Wan Bin Jiang Qingguo Feng National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Material Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1D-21502 GeesthachtGermany School of Mechanical Engineering Dongguan University of TechnologyDongguan 523808China

The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al_(2)O_(3) whiskers in Mg matrix composites.The Mg powders were decorated with sodium dodecylbenzene sulfonate(C_(18)H_(29)NaO_(3)S,SDBS)and were introduced to the cathode group on their surface.The Al_(2)O_(3) whiskers were modified by the cetyl trimethyl ammonium bromide(C_(19)H_(42)BrN,CTAB)and were featured in the anode group.The suitable contents of CTAB and SDBS,the application atmosphere,and the type of solvents were investigated.Dispersion results showed that adding 2wt%SDBS into Mg powders and adding 2wt%CTAB into Al_(2)O_(3) whiskers pro-moted the formation of more uniformly mixed composite powders,compared to those of conventional ball milling via scanning electron micro-scopy(SEM)analysis.Meanwhile,the calculated results derived from first-principle calculations also demonstrated the stronger cohesion between Al_(2)O_(3) whisker reinforcements and Mg matrix than undecorated composite powders.After preparation by powder metallurgy,the mor-phology,grain size,hardness,and standard deviation coefficient of composites were analyzed to evaluate the dispersed efficiency.The results indicated that the modification of homogenized dispersed Al_(2)O_(3) whiskers in composites contributed to the refinement of 26%in grain size and the improvement of 20%in hardness compared with pure Mg,and the reduction of 32.5%in the standard deviation coefficient of hardness compared with the ball-milling sample.

关键词： magnesium-based composites Al_(2)O_(3)whiskers potential difference dispersion

Synthesis,microstructure,and properties of high purity Mo_(2)TiAlC_(2) ceramics fabricated by spark plasma sintering

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Journal of Advanced Ceramics 2020年第6期9卷 759-768页

作者： Yunhui NIU Shuai FU Kuibao ZHANG Bo DAI Haibin ZHANG Salvatore GRASSO chunfeng hu State Key Laboratory of Environment-Friendly Energy Materials Southwest University of Science and TechnologyMianyang 621010China Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Institute of Nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China

The synthesis,microstructure,and properties of high purity dense bulk Mo_(2)TiAlC_(2) ceramics were studied.High purity Mo_(2)TiAlC_(2) powder was synthesized at 1873 K starting from Mo,Ti,Al,and graphite powders with a molar ratio of 2:1:1.25:2.The synthesis mechanism of Mo_(2)TiAlC_(2) was explored by analyzing the compositions of samples sintered at different temperatures.It was found that the Mo_(2)TiAlC_(2) phase was formed from the reaction among Mo3Al2C,Mo2C,TiC,and C.Dense Mo_(2)TiAlC_(2) bulk sample was prepared by spark plasma sintering(SPS)at 1673 K under a pressure of 40 MPa.The relative density of the dense sample was 98.3%.The mean grain size was 3.5μm in length and 1.5μm in width.The typical layered structure could be clearly observed.The electrical conductivity of Mo_(2)TiAlC_(2) ceramic measured at the temperature range of 2-300 K decreased from 0.95×10^(6) to 0.77×10^(6)Ω^(-1)·m^(-1).Thermal conductivity measured at the temperature range of 300-1273 K decreased from 8.0 to 6.4 W·(m·K)^(-1).The thermal expansion coefficient(TEC)of Mo_(2)TiAlC_(2) measured at the temperature of 350-1100 K was calculated as 9.0×10^(-6) K^(-1).Additionally,the layered structure and fine grain size benefited for excellent mechanical properties of low intrinsic Vickers hardness of 5.2 GPa,high flexural strength of 407.9 MPa,high fracture toughness of 6.5 MPa·m^(1/2),and high compressive strength of 1079 MPa.Even at the indentation load of 300 N,the residual flexural strength could hold 84% of the value of undamaged one,indicating remarkable damage tolerance.Furthermore,it was confirmed that Mo_(2)TiAlC_(2) ceramic had a good oxidation resistance below 1200 K in the air.

关键词： MAX phase Mo_(2)TiAlC_(2) synthesis microstructure properties

Spark plasma sintering of damage tolerant and machinable YAM ceramics

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Journal of Advanced Ceramics 2013年第2期2卷 193-200页

作者： Qian WANG Salvatore GRASSO chunfeng hu Haibin ZHANG Shu CAI Yoshio SAKKA Qing huANG Ningbo Institute of Materials Technology and Engineering(NIMTE) Chinese Academy of Sciences(CAS)Ningbo 315201China Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education Tianjin UniversityTianjin 300072China School of Engineering&Materials Science and Nanoforce Technology Ltd. Queen Mary University of LondonMile End RoadLondon E14NSUK China Academy of Engineering Physics Mianyang 621900China National Institute for Materials Science(NIMS) TsukubaIbaraki 305-0047Japan

Single-phase Y_(4)Al_(2)O_(9)(YAM)powders were synthesized via solid-state reaction starting from nano-sized Al_(2)O_(3) and Y_(2)O_(3).Fully dense(99.5%)bulk YAM ceramics were consolidated by spark plasma sintering(SPS)at 1800℃.We demonstrated the excellent damage tolerance and good machinability of YAM ceramics.Such properties are attributed to the easy slipping along the weakly bonded crystallographic planes,resulting in multiple energy dissipation mechanisms such as transgranular fracture,shear slipping and localized grain crushing.

关键词： ceramic synthesis microstructure property damage tolerance

Theoretical prediction,synthesis,and crystal structure determination of new MAX phase compound V2SnC

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Journal of Advanced Ceramics 2020年第4期9卷 481-492页

作者： Qiang Xu Yanchun Zhou Haiming Zhang Anna Jiang Quanzheng Tao Jun Lu Johanna Rosén Yunhui Niu Salvatore Grasso chunfeng hu Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu610031China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing100076China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China Thin Film Physics Division Department of PhysicsChemistryand Biology(IFM)Linköping UniversityLinköpingSE-58183Sweden State Key Laboratory of Environment-friendly Energy Materials Southwest University of Science and TechnologyMianyang621010China

Guided by the theoretical prediction,a new MAX phase V2SnC was synthesized experimentally for the first time by reaction of V,Sn,and C mixtures at 1000°C.The chemical composition and crystal structure of this new compound were identified by the cross-check combination of first-principles calculations,X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDS),and high resolution scanning transmission electron microscopy(HR-STEM).The stacking sequence of V2C and Sn layers results in a crystal structure of space group P63/mmc.The a-and c-lattice parameters,which were determined by the Rietveld analysis of powder XRD pattern,are 0.2981(0)nm and 1.3470(6)nm,respectively.The atomic positions are V at 4f(1/3,2/3,0.0776(5)),Sn at 2d(2/3,1/3,1/4),and C at 2a(0,0,0).A new set of XRD data of V2SnC was also obtained.Theoretical calculations suggest that this new compound is stable with negative formation energy and formation enthalpy,satisfied Born-huang criteria of mechanical stability,and positive phonon branches over the Brillouin zone.It also has low shear deformation resistance c44(second-order elastic constant,cij)and shear modulus(G),positive Cauchy pressure,and low Pugh’s ratio(G/B=0.500<0.571),which is regarded as a quasi-ductile MAX phase.The mechanism underpinning the quasi-ductility is associated with the presence of a metallic bond.

关键词： V2SnC new MAX phase compound crystal structure first-principles calculations

Cold Hydrostatic Sintering:From shaping to 3D printing

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Journal of Materiomics 2019年第3期5卷 496-501页

作者： Anna Jiang Daoyao Ke Ludi Xu Qiang Xu Jiang Li Jiabei Wei chunfeng hu Salvatore Grasso Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu610031China Key Laboratory of Transparent Opto-functional Inorganic Materials Shanghai Institute of CeramicsChinese Academy of SciencesShanghai201899China

We developed a novel consolidation technique,Cold Hydrostatic Sintering(CHS),which allows near full densification of silica.The technique is inspired by biosilicification and geological formation of siliceous rocks.Unlike established cold sintering method which is based on uniaxial pressure,CHS employs an isostatic pressure to enable room temperature consolidation of bulks having a complex threedimensional shape.The resulting material is transparent(in line transmittance exceeding 70% in the visible range)and amorphous.After drying,the Vickers hardness was as high 1.4 GPa which half of materials consolidated at 1200℃ and it is the highest among all materials processed at room temperature.The CHS method,because of its simplicity,might be suitable for broad range of applications including 3D printing,mould forming and preparation of multi-layered devices.Because of the absence of the firing step,CHS could be directly integrated in the manufacturing of a wide range of hybrid(organic/inorganic)materials for functional and biological applications.

关键词： Silica Cold Hydrostatic Sintering(CHS) Shaping 3D printing