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Journal of Materials Science & Technology 2010年第4期26卷 344-350页

作者： Xianjing Jin Aimin Chang Huimin Zhang Dongyan Zhang Xinjiang Key Laboratory of Electronic Information Materials and Devices Xinjiang Technical Institute of Physics and Chemistry CAS Urumqi 830011 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

In this paper, a quaternary system of Mn0.43Ni0.9CuFe0.67O4 negative temperature coefficient （NTC） thermistor ceramic prepared by solid/solid reaction was sintered by microwave and conventional method, respectively. To characterize the sinterability of the samples, the densification parameter, porosity and grain size distribution of the bulk were determined. The crystal structure, phase compositions, morphology and impedance of the samples were analyzed by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy-dispersive spectroscopy （EDS） and impedance analysis. The experimental results confirmed that the sinterability and electrical properties of ceramics were homogenously improved by microwave sintering.

关键词： Microwave sintering Mn0.43Ni0.9CuFe0.67O4 sinterability Electrical Negative temperature coefficient (NTC)

DEPENDENCE　OF　sinterability　ON　STATE　OF　AGGLOMERATION　OF　ULTRAFINE　ZrO_2，（Y_2O_3）　POWDERS

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中国有色金属学会会刊：英文版 1995年第3期5卷 37-40,44页

作者： Rongde, Ge Zhihong, Liu Huiguang, Chen Duomo, Zhang Tiancong, Zhao Central South Univ of Technology Changsha China

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关键词： zirconia ultrafine powder agglomeration sinterability

sinterability EXPERIMENTS OF PORTAND CEMENT WITH IRON-TAILINGS AS RAW MATERIALS

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Acta Metallurgica Sinica(English Letters) 1999年第5期12卷 1059-1063页

作者： J.Z.Wang and Y.H.Zhao Shenyang Architectural and Civil Engineering Institute, Shenyang 110015,China

The sinterability of Portland Cement with iron tailings as raw materials are studied. Experimental results showed that iron tailings, owing to the existences of the trace elements, play an important role in improving ... 详细信息

关键词： iron tailings sinterability portland cement trace elements

Effect of TiO_2 on the sinterability and Microstructure of Mullite Sythesized from Al(OH)_3 and SiO_2

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China's Refractories 2006年第2期15卷 3-6页

作者： LIANG Yonghe YIN Yucheng WU Yunyun WANG Jibao The Hubei Province Key Laboratory of Refractory Ceramics Ministry-Province Jointly Constructed Cultivation Base for State Key Laboratory Hubei Wuhan 430081

Using analytical pure Al（ OH）3 , SiO2 , TiO2 as raw materials, effect of TiO2 on the sinterability and microstructure of mullite synthesized from Al （ OH）3 and SiO2 was investigated in this paper by XRD , SEM and EPAX. Results show that TiO2 can promote the sintering property when the amount is below 6%, the sinterability of samples becomes better with the increase of the amount of TiO2, microstructure of samples densify gradually, and the best effect can be achieved when the amount of TiO2 is 6%. It was shown by XRD analysis that no Al2TiO5 present when the amount of TiO2 is below 6%, TiO2 existed in the form of solid-solution and glass phase; When the amount of TiO2 is up to 6%, the sinterability of samples becomes worse with the increase of TiO2 added, microstructure of samples began to loosen, Al2TiO5 can be observed in samples and its amount increase with the increase of TiO2.

关键词： Mullite sinterability TiO2 Microstructure

Cr-assisted low-temperature densification of(Ti,Zr,Nb,Ta,Mo)C high-entropy carbides with ultrafine grain and enhanced hardness

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Journal of Advanced Ceramics 2024年第6期13卷 780-788页

作者： Yang Liu Jiaji Liang Weiming Guo Shikuan Sun Yu Tian Hua-Tay Lin School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China State Key Laboratory of High Performance Tools Guangdong University of TechnologyGuangzhou 510006China School of Material Science and Energy Engineering Foshan UniversityFoshan 528000China

While the use of low-melting-point metals as sintering aids for high-entropy carbide(HEC)ceramics has been well established,their existence can compromise hardness due to residual metallic *** study demonstrates an innovative strategy to meet this challenge,where(Ti,Zr,Nb,Ta,Mo)C high-entropy carbide ceramics with ultrafine grains and enhanced hardness are obtained through chromium(Cr)-metal-assisted spark plasma sintering(SPS)at a temperature as low as 1600℃.The results show that the addition of 5 vol%Cr promotes the formation of highly densified single HEC phase ceramics with a high relative density(98.4%)and an ultrafine-grained microstructure(0.17μm).This low-temperature densification mechanism can be attributed to Cr’s solid-solution effect within the matrix and the increased carbon vacancies generated during *** grain size of the(Ti,Zr,Nb,Ta,Mo)C ceramics with 5 vol%Cr metal addition is significantly smaller than that of Cr-free(Ti,Zr,Nb,Ta,Mo)C ceramics sintered at 2000℃(3.03μm)or via traditional low-temperature liquid-phase sintering(1.3–1.5μm).Importantly,the addition of 5 vol%Cr substantially increased the hardness of the ceramics,with a remarkable increase from 23.57 to 28.16 GPa compared to that of the pure(Ti,Zr,Nb,Ta,Mo)C ceramics,owing to the fine-grain strengthening and solid-solution strengthening *** work highlights the uniqueness of Cr metal as a sintering aid in achieving densification and hardness improvements in(Ti,Zr,Nb,Ta,Mo)C ceramics,offering a promising strategy for improving the properties of HEC materials for further development in the near future.

关键词： solid solution sinterability hardness enhancement (Ti,Zr,Nb,Ta,Mo)C high-entropy carbide(HEC)ceramics

Low-agglomerated yttria nanopowders via decomposition of sulfate-doped precursor with transient morphology

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Journal of Rare Earths 2014年第4期32卷 320-325页

作者： R.P.Yavetskiy D.Yu.Kosyanov V.N.Baumer A.G.Doroshenko A.I.Fedorov N.A.Matveevskaya A.V.Tolmachev O.M.Vovk Institute for Single Crystals of NAS of Ukraine State Scientific Institution"Institute for Single Crystals"of NAS of Ukraine

The fabrication peculiarities of low-agglomerated yttria （Y2O3） nanopowders via thermal decomposition of sulfate-doped precursor with transient morphology were studied. It was determined that Y2（OH）5（NO3）x（CO2）y（SO4）z·nH2O （n=1-2） crystalline precursor underwent fragmentation and decomposition into isolated quasi-spherical Y2O3 particles upon calcination. Effect was con-nected with minimizing the free energy of the plate-like crystallites via reducing the contact surface until to the moment of spheroidi-zation and attainment of isolation that occurred atТ=1100 °С. Residual sulfate ions slowed down the surface diffusion during heat treatment thus retaining quasy-spherical morphology and low aggregation degree of Y2O3 nanopowders. Sulfate-doped yttria nanopowders with medium particle size of 53±13 nm possessed improved sinterability in comparison with undoped ones arising from finer particle size, narrower particle distribution and lower agglomeration degree.

关键词： precursor transient morphology sulfate-ions yttria nanopowders particle size sinterability rare earths

Microstructure,crystalline phase and electrical properties of Li_(0.06)(Na_(0.5)K_(0.5))_(0.94)Nb_(1-2x/5)Mg_xO_3 lead-free piezoelectric ceramics

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 340-346页

作者： Hai-tao Li Bo-ping Zhang Qian Zhang Peng-peng Shang Gao-lei Zhao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Henan University of Science and Technology Luoyang 471003 China

MgO-modified Li0.06（Na0.5K0.5）0.94NbO3O3 （L6NKN） lead-free piezoelectric ceramics were synthesized by normal sintering at a rela- tively low temperature of 1000℃. The crystalline phase, microstructure, and electrical properties of the ceramics were investigated with a special emphasis on the influence of MgO content. The addition of MgO effectively improves the sintembility of the L6NKN ceramics. X-my diffr cfion analysis indicates that the morphotropic phase boundary （MPB） separating orthorhombic and tetragonal phases for the ceramics lies in the range of Mg doping content （x） from 0.3at% to 0.7at%. High electrical properties of the piezoelectric constant （d33=238 pC/N）, planar electromechanical coupling coefficient （kp=41.5%）, relative dielectric constant （εr=905）, and remanent polarization （Pr=38.3 μC/cm2） are obtained from the specimen with x=0.5at%, which suggests that the Li0.06（Na0.5K0.5）0.94Nb（1-2x/5）MgxO3 （x=0.5at%） ceramic is a promising lead-free piezoelectric material.

关键词： lead-flee piezoelectric ceramics sinterability sintering morphotropic phase boundary

Synthesis Yttrium Aluminum Garnet Precursor via Homogeneous Precipitation under Microwave Irradiation

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Journal of Rare Earths 2004年第6期22卷 780-784页

作者：王介强高新睿姜奉华于庆华郑少华 Material Science and Engineering School Jinan University Jinan 250022China

The lowly-agglomerated single-phase YAG nanopowders were synthesized for the first time by the microwave homogeneous precipitation in the presence of urea. The composition and transformations during calcination of YAG precursor were analyzed by IR, DTA/TG and XRD. The size and morphology of YAG powders were characterized by LD and TEM methods. Results show that amorphous precursor synthesized under [urea]/[metal ions] molar ratio of 15 crystallizes directly to single-phase YAG at 900degreesC. The size distribution and sinterability of YAG powders are obviously improved by adding (NH4)(2)SO4 into the reaction solution. YAG powders obtained from precursor with the (NH4)(2)SO4 content of 8% have good sinterability and are highly densified at a temperature of 1500degreesC

关键词： microwave homogenous synthesis YAG powders sinterability (NH4)(2)SO4 rare earths

Spark Plasma Sintering Properties of Ultrafine Ti(C,N)-based Cermet

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Journal of Wuhan University of Technology(Materials Science) 2004年第1期19卷 69-72页

作者：丰平 Huazhong University of Science and Technology

Ultrafine Ti(C,N)-based cermet was sintered by SPS from 1050℃ to 1450℃ and its sintering properties,such as porosity,mechanical properties and phase transformation,were investigated by optical microscopy (OM),scanning electron microscopy (SEM),X-ray diffraction (XRD),and differential scanning calorimeter (DSC).It is found that the spark plasma sintering properties of Ti(C,N)-based cermet differ from those of conventional vacuum *** liquid phase appearance is at least lower by 150℃ than that in vacuum *** porosity decreases sharply below 1 200℃ and reaches minimum at 1 200℃,and afterwards it almost keeps invariable and no longer *** remarkably accelerates the phase transformation of Ti(C,N)-based cermet and it has a powerful ability to remove oxides in Ti(C,N)-based *** 1 350℃,denitrification *** graphite phase formed above 1 430℃.Both the porosity and graphite are responsible for the poor TRS.

关键词： Ti(C,N)-based cermets ultrafine cermet spark plasma sintering (SPS) sinterability densification deoxidation denitrification

Effects of Nucleating Additives on Crystallization and Properties of CaO-B_2O_3-SiO_2 Glass-ceramics

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Journal of Wuhan University of Technology(Materials Science) 2009年第6期24卷 997-1000页

作者：王中俭 Key Laboratory for Ultrafine Materials of Ministry of Education Shanghai Key Laboratory of Advanced Polymeric MaterialsSchool of Materials Science and EngineeringEast China University of Science and Technology

ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO2 as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO2 containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 ℃ for 10 min, with low dielectric constant （5.87） and loss （3.21×10^-4）, which is desirable for LTCC application.

关键词： CaO-B2O3-SiO2 glass-ceramics nucleating additives crystallization sinterability