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Effect of Heat Treatment on High Temperature Stress Rupture Strength of Brazing Seam for Nickel-base Superalloy

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Journal of university of science and Technology beijing 2001年第2期8卷 123-125页

作者： junying zhang, Zhongtai zhang, Jisheng Sun, Xiaofang Liu, Wei Tian (State key laboratory of new ceramics and fine processing, department of materials science and engineering, tsinghua university, beijing 100084, china) (beijing Institute of Aeronautical Tsing Hua Univ Dept Mat Sci & Engn State Key Lab New Ceram & Fine Proc Beijing 100084 Peoples R China Inst Aeronaut Mat Beijing 100095 Peoples R China Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China

In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam especially morphology of gamma ' phase and boride was observed and the strength of brazing seam was measured in this process. The results show that heat treatment can enhance high-temperature stress rupture strength by improving the microstructure of brazing seam. The strength of brazing seam after solution heat treatment decreases in comparison with that only after diffusion treatment while aging treatment after solution heat treatment increases the strength of brazing seam.

关键词： wide-gap brazing high temperature stress rupture strength microstructure nickel-base superalloy

EffectofEr^(3+) and Nd^(3+)doping on the luminescent properties of BaMgAl_(10)O_(17):Euphosphor

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Rare Metals 2003年第1期22卷 60-63页

作者： zhanglin zhangjunying zhangZhongtai CenterformaterialsPhysiceandchentistry SchoolofSciencesBeiHangUniversityBeijing100083China PersonnelDivision UniversityofSciehceandTechnologyBeijingBeijing100083China StatekeylaboratoryofnewCeram

BaMgAl_(10)O_(17):Eu blue phosphors were synthesized and the effect of dopingE^(3+) and Nd^(3+) ions in the phosphor on the luminescent properties was investigated. When thecontent of Er^(3+) and Nd^(3+) ions is small, the phosphor remains single phase and the luminescentintensity of Eu^(2+) increases effectively. When Er^(3+) is doped, the shape of the excitationspectrum of the phosphor in the UV (ultraviolet) region remains unchanged. As Nd^(3+) is doped inthe phosphor, the location and intensity of the two excitation peaks, and the emission intensityratio excited by corresponding UV change dramatically owing to the alternation of crystal fieldsplitting and level barycenter of 4f^6 5d configuration of Eu^(2+) ion.

关键词： phosphor spectrum luminescent property

A novel synthetic route for LiFePO_4/C cathode materials by addition of starch for lithium-ion batteries

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Chinese Chemical Letters 2007年第2期18卷 237-240页

作者： Shao Hua Luo, Zi Long Tang, Jun Biao Lu, Zhong Tai zhang State key laboratory of new ceramics and fine processing, department of materials science and engineering, tsinghua university, beijing 100084, china Graduate School at Shenzhen, tsinghua university, Shenzhen 518055, china [a]State key laboratory of new ceramics and fine processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 China [b]Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China

LiFePO4/Carbon composite cathode material was prepared using starch as carbon source by spray-pelleting and subsequent pyrolysis in N2. The samples were characterized by XRD, SEM, Raman, and their electrochemical performance was investigated in terms of cycling behavior. There has a special micro-morphology via the process, which is favorable to electrochemical properties. The discharge capacity of the LiFePO4.C composite was 170 mAh g-1, equal to the theoretical specific capacity at 0.1 C rate. At 4 C current density, the specific capacity was about 80 mAh g-1, which can satisfy for transportation applications if having a more flat discharge flat.

关键词： Lithium-ion batteries Cathode material Carbon coated LiFePO4 Spray-pelleting

Vibration-assisted material damage mechanism:From indentation cracks to scratch cracks

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Chinese Journal of Aeronautics 2024年第8期37卷 527-546页

作者： Bingrui LV Bin lin Tianyi SUI Chunyan LIU Jinshuo zhang Longfei WANG Xuhui chen Jingguo ZHOU key laboratory of Advanced ceramics and Machining Technology Ministry of EducationTianjin UniversityTianjin 300072China key laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin UniversityTianjin 300072China science and Technology of Advanced Functional Composite laboratory Aerospace Research Institute of Materials and Processing TechnologyBeijing 100076China

Vibration-assisted grinding is one of the most promising technologies for manufacturing optical components due to its efficiency and quality ***,the damage and crack propagation mechanisms of materials in vibration-assisted grinding are not well *** order to elucidate the mechanism of abrasive scratching during vibration-assisted grinding,a kinematic model of vibration scratching was *** influence of process parameters on the evolution of vibration scratches to indentation or straight scratches is revealed by displacement metrics and velocity ***,scratch and vibration scratch experiments were performed on quartz glass,and the results showed that the vibration scratch cracks are a combination of indentation cracks and scratch *** scratch cracks change from indentation cracks to scratch cracks as the indenter moves from the entrance to the exit of the workpiece or as the vibration frequency changes from high to low.A vertical vibration scratch stress field model is established for the first time,which reveals that the maximum principal stress and tensile stress distribution is the fundamental cause for inducing the transformation of the vibration scratch cracking *** model provides a theoretical basis for understanding of the mechanism of material damage and crack propagation during vibration-assisted grinding.

关键词： Vibration assisted grinding Indentation Vibration scratch Material removal mechanism Stress field model Crack propagation mechanism

Improved piezoelectric and luminescent properties in Sm-modified Bi_(0.5)Na_(0.5)TiO_(3)-BaTiO_(3) multifunctional ceramics

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Journal of Materiomics 2024年第4期10卷 803-810页

作者： Shuai cheng Kehong zhang Chongyang Li Boping zhang Jianguo chen Kang Sun Changrong zhou Jingtai Zhao Qisheng lin Guanghui Rao Siqi Shi School of materials science and engineering Shanghai UniversityShanghai200444China Guangxi key laboratory of Information materials&School of materials science and engineering Guilin University of Electronic TechnologyGuilin541004GuangxiChina School of materials science and engineering University of Science and Technology BeijingBeijing100083China School of Information engineering Lanzhou University of Finance and EconomicsLanzhou730020China

The 0.93(Na_(0.5)Bi_(0.5))_(1–x)Sm_(x)TiO_(3)-0.07BaTiO_(3) multifunctional ceramics were prepared by solid-phase reaction *** phase structure,microstructure,electrical and photoluminescent properties were systematically *** increasing x,the ceramics undergoes the phase transition from rhombohedral to tetragonal with some rhombohedral distortion,along with a reduced grain size and increased relative *** the other hand,the Sm3+doping enhances the electric-field driven reversible phase transition and domain size,and reduces the domain walls,thereby contributing to improved piezoelectricity and decreased depolarization temperature(T_(d))from 91℃ to 40℃.Excellent piezoelectric properties of d_(33)=213 pC/N and kp=29.9% are achieved in the x=0.010 *** excitation(407 nm),the Sm^(3+)-doped ceramic exhibits bright reddish-orange fluorescence at 564,599,646 nm and 710 nm.A polarization-induced enhancement of photoluminescence is obtained in BNBT-_(x)Sm ceramics with an improved relative intensity of emission band at 646 *** results indicate that Sm^(3+)-doped BNBT ceramics show great potential in electro-optic integration and coupling device applications.

关键词： Piezoelectricity Curie temperature Phase transitions Thermal stability Photoluminescence

Highly Active Rutile TiO2 for Photocatalysis

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稀有金属材料与工程 2006年第S3期 396-399页

作者： Junping Yan~(1,2) Zilong Tang~1 Zhongtai zhang~1 Zhigang Zhou~1 (1.State key laboratory of new ceramics and fine processing,department of materials science and engineering,tsinghua university,beijing 100084,china) (2.College of materials science and engineering,Taiyuan university of Technology,Taiyuan 030024,china)

Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection *** results showed that rutile titania formed at 70℃without calcination in *** rutile TiO2had good crystalline and small particle *** formation mechanism of rutile was also *** photocatalytic activity of the prepared particles was tested for the degradation of methyl *** photocatalytic activity of rutile TiO2was higher than those obtained from Degussa P-25 *** reasons for high photocatalytic activity of futile were discussed.

关键词： rutile titania photocatalyst needle shape

Preparation,Characterization and Applications of Titanate/Titania Nanocrystals

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稀有金属材料与工程 2006年第S3期 638-641页

作者： Junrong Li~(1,2) Zilong Tang~1 Zhongtai zhang~1 Zhigang Zhou~1 (1.State key laboratory of new ceramics and fine processing,department of materials science and engineering,tsinghua university,beijing 100084,china) (2.beijing Institute of Space Medico-engineering,beijing 100094,china)

The present paper focused on the preparation of hydrogen titanate nanotubes and nanowires and their conversion into titania by heat *** structural,morphology and optical properties of as-prepared nanostructured titanate and titania were investigated by transmission electron microscopy (TEM),X-ray diffraction (XRD) and diffusive reflectance *** slim diameter of these nanostructured titanate and titania,the versatile crystal structure and special optical and electronic properties may make them find versatile applications in chemical sensors for multiple purposes.

关键词： titanate titania nanocrystals preparation applications

弛豫铁电材料在准同型相界附近结构和性能研究的最新进展

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无机材料学报 2002年第3期17卷 385-391页

作者：张孝文陈克丕清华大学材料系新型陶瓷与精细工艺国家重点实验室北京100084

铅系钙钛矿结构弛豫铁电材料在准同型相界区域的单晶,因为具有优异的介电、压电性能及潜在的应用前景,近年来已经引起了广泛的重视,本文较详细地介绍了其反常性能的一些特征,以及对其起源在理论及实验观察上的最新进展,重点介绍了自发... 详细信息

铅系钙钛矿结构弛豫铁电材料在准同型相界区域的单晶,因为具有优异的介电、压电性能及潜在的应用前景,近年来已经引起了广泛的重视,本文较详细地介绍了其反常性能的一些特征,以及对其起源在理论及实验观察上的最新进展,重点介绍了自发极化在外场下进行偏转的理论,以及近年来用同步辐射的Ｘ射线衍射实验研究结果,发现在原先以为只有菱方相和四方相的准同型相界区域存在着单斜相．

关键词：驰豫铁电材料准同型相界结构性能铁电单晶极化偏转

Investigation of improving the thermophysical properties and corrosion resistance of RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7)multiphase silicates by component design with RE doping

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Journal of Advanced ceramics 2024年第6期13卷 842-860页

作者： Zeyu chen Yiling Huang Zhaoxuan zhang Wei Zheng Xuemei Song Yaran Niu Yi Zeng The State key Lab of High Performance ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of materials science and Optoelectronics engineering University of Chinese Academy of SciencesBeijing 100049China key laboratory of Inorganic Coating materials CAS Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China

In this research,a novel method for regulating components in RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7)multiphase silicates was developed,combining the benefits of a suitable thermal expansion coefficient(CTE)and outstanding corrosion resistance against calcium–magnesium–alumino–silicate(CMAS).This approach enhanced the overall thermophysical ***,the results from the CMAS corrosion resistance test indicated that(Lu_(1/3)Yb_(1/3)Tm_(1/3))_(2)SiO_(5)/(Lu_(1/3)Yb_(1/3)Tm_(1/3))_(2)Si_(2)O_(7)and(Lu_(1/4)Yb_(1/4)Tm_(1/4)Er_(1/4))_(2)SiO_(5)/(Lu_(1/4)Yb_(1/4)Tm_(1/4)Er_(1/4))_(2)Si_(2)O_(7)exhibited exceptional resistance to CMAS penetration,even at temperatures up to 1500℃.To comprehend the corrosion mechanism of CMAS on these silicates,we introduced a reaction–diffusion model,which involved observing the changes in the interface between the corrosion product layer and the silicate *** was achieved using electron backscatter diffraction(EBSD).These findings lay a theoretical basis for selecting rare earth elements in RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7)multiphase silicates based on the radii of different rare earth cations.

关键词： thermal conductivity environmental barrier coatings(EBCs) thermal expansion coefficient(CTE) multiphase silicates calcium-magnesium-alumino-silicate(CMAS)corrosion resistance reaction-diffusion