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Robust and Tunable Ferroelectricity in Ba/Co Codoped (K_(0.5)Na_(0.5))NbO_(3) Ceramics
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作者 刘佳讯 查节林 +5 位作者 杨玉龙 吕笑梅 胡雪莉 阎朔 吴子敬 黄凤珍 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第7期152-160,共9页
The 0.98(K_(0.5)Na_(0.5))NbO_(3)-0.02Ba(Nb_(0.5)Co_(0.5))O_(3-δ) ceramics with doped Ba^(2+) and Co^(2+) ions are fabricated,and the impacts of the thermal process are studied.Compared with the rapidly cooled (RC) sa... The 0.98(K_(0.5)Na_(0.5))NbO_(3)-0.02Ba(Nb_(0.5)Co_(0.5))O_(3-δ) ceramics with doped Ba^(2+) and Co^(2+) ions are fabricated,and the impacts of the thermal process are studied.Compared with the rapidly cooled (RC) sample,the slowly cooled (SC) sample possesses superior dielectric and ferroelectric properties,and an 11 K higher ferroelectricparaelectric phase transition temperature,which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy.Heat treatment can reversibly modulate the content of the oxygen vacancies,and in turn the ferroelectric hysteresis loops of the samples.Finally,robust and tunable ferroelectric property is achieved in SC samples with good structural integrity. 展开更多
关键词 ceramics FERROELECTRIC treatment
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Preparation and Photostriction Properties of BiFeO_(3)-BaTiO_(3)Ceramics
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作者 ZHENG Zewei ZHANG Liqiang +3 位作者 CHEN Chen CAO Minghe YI Zhiguo LIU Hanxing 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第5期1079-1086,共8页
Under illumination by 405,520 and 655 nm monochromatic visible light(light intensity of 30 kW/m^(2)),large photostriction(ΔL/L)of 0.19%,0.13%and 0.26%for 67BiFeO_(3)-33BaTiO_(3)(67BF-33BT)lead-free ferroelectric cera... Under illumination by 405,520 and 655 nm monochromatic visible light(light intensity of 30 kW/m^(2)),large photostriction(ΔL/L)of 0.19%,0.13%and 0.26%for 67BiFeO_(3)-33BaTiO_(3)(67BF-33BT)lead-free ferroelectric ceramics are obtained,respectively.By studying the ferroelectric and photoelectric properties in conjunction with in situ Raman spectroscopy,it is found that the photostrictive effect of 67BF-33BT is not caused by the electrical strain induced by abnormal photovoltaic voltage,but related to the optical induced oxygen octahedral distortion.The 67BF-33BT lead-free ferroelectric material with excellent photostrictive response in the visible light region is expected to play an important role in the field of optical drive electromechanical devices. 展开更多
关键词 ferroelectric ceramics photostrictive effect visible light response
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Microstructure Characteristics and Possible Phase Evolution of the Coal Gangue-Steel Slag Ceramics Prepared by the Solid-State Reaction Methods
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作者 刘文洁 WANG Yang +1 位作者 LI Jingtao 李宝让 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第4期921-930,共10页
Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios... Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios,from 100%steel slag to 100%coal gangue at 10%intervals,microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction,scanning electron microscopy,mercury intrusion porosimetry and Archimedes boiling method.The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics.The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8,which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature.Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity. 展开更多
关键词 steel slag-coal gangue ceramics SYNTHESIS phase evolution microstructure characteristics
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A critical review of direct laser additive manufacturing ceramics
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作者 Dake Zhao Guijun Bi +4 位作者 Jie Chen WaiMeng Quach Ran Feng Antti Salminen Fangyong Niu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第12期2607-2626,共20页
The urgent need for integrated molding and sintering across various industries has inspired the development of additive manu-facturing(AM)ceramics.Among the different AM technologies,direct laser additive manufacturin... The urgent need for integrated molding and sintering across various industries has inspired the development of additive manu-facturing(AM)ceramics.Among the different AM technologies,direct laser additive manufacturing(DLAM)stands out as a group of highly promising technology for flexibly manufacturing ceramics without molds and adhesives in a single step.Over the last decade,sig-nificant and encouraging progress has been accomplished in DLAM of high-performance ceramics,including Al_(2)O_(3),ZrO_(2),Al_(2)O_(3)/ZrO_(2),SiC,and others.However,high-performance ceramics fabricated by DLAM face challenges such as formation of pores and cracks and resultant low mechanical properties,hindering their practical application in high-end equipment.Further improvements are necessary be-fore they can be widely adopted.Methods such as field-assisted techniques and post-processing can be employed to address these chal-lenges,but a more systematic review is needed.This work aims to critically review the advancements in direct selective laser sintering/melting(SLS/SLM)and laser directed energy deposition(LDED)for various ceramic material systems.Additionally,it provides an overview of the current challenges,future research opportunities,and potential applications associated with DLAM of high-perform-ance ceramics. 展开更多
关键词 3D printing laser additive manufacturing ceramics quality MICROSTRUCTURE mechanical properties
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Microstructure and Oxidation Behavior of ZrB_(2)-SiC Ceramics Fabricated by Tape Casting and Reactive Melt Infiltration
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作者 TAN Min CHEN Xiaowu +5 位作者 YANG Jinshan ZHANG Xiangyu KAN Yanmei ZHOU Haijun XUE Yudong DONG Shaoming 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2024年第8期955-964,共10页
ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to... ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to the conventional preparation method,reactive synthesis allows for the more facile production of ultra-high temperature ceramics with fine particle size and homogeneous composition.In this work,ZrSi_(2),B4C,and C were used as raw materials to prepare ZrB_(2)-SiC via combination of tape casting and reactive melt infiltration herein referred to as ZBC ceramics.Control sample of ZrB_(2)-SiC was also prepared using ZrB_(2) and SiC as raw materials through an identical process designated as ZS ceramics.Microscopic analysis of both ceramic groups revealed smaller and more uniformly distributed particles of the ZrB_(2) phase in ZBC ceramics compared to the larger particles in ZS ceramics.Both sets of ceramics underwent cyclic oxidation testing in the air at 1600℃for a cumulative duration of 5 cycles,each cycle lasting 2 h.Analysis of the oxidation behavior showed that both ZBC ceramics and ZS ceramics developed a glassy SiO_(2)-ZrO_(2) oxide layer on their surfaces during the oxidation.This layer severed as a barrier against oxygen.In ZBC ceramics,ZrO_(2) is finely distributed in SiO_(2),whereas in ZS ceramics,larger ZrO_(2) particles coexist with glassy SiO_(2).The surface oxide layer of ZBC ceramics maintains a dense structure because the well-dispersed ZrO_(2) increases the viscosity of glassy SiO_(2),preventing its crystallization during the cooling.Conversely,some SiO_(2) in the oxide layer of ZS ceramics may crystallize and form a eutectic with ZrO_(2),leading to the formation of ZrSiO_(4).This leads to cracking of the oxide layer due to differences in thermal expansion coefficients,weakening its barrier effect.An analysis of the oxidation resistance shows that ZBC ceramics exhibit less increase in oxide layer thickness and mass compared to ZS ceramics,suggesting superior oxidation resistance of ZBC ceramics. 展开更多
关键词 ultra-high temperature ceramic ZRB2-SIC oxidation behavior reactive melt infiltration
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Low-firing and temperature stability regulation of tri-rutile MgTa_(2)O_(6)microwave dielectric ceramics
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作者 Chengzhi Xu Hongyu Yang +5 位作者 Hongcheng Yang Linzhuang Xing Yuan Wang Zhimin Li Enzhu Li Guorui Zhao 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第8期1935-1943,共9页
A glass frit containing Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa_(2)O_(6)ceramics in this stud... A glass frit containing Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa_(2)O_(6)ceramics in this study.The good low-firing effects are presented due to the high matching relevance between Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass and MgTa_(2)O_(6)ceramics.The pure tri-rutile MgTa_(2)O_(6)structure remains unchanged,and high sintering compactness can also be achieved at 1150℃.We found that the Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass not only greatly improves the low-temperature sintering characteristics of MgTa_(2)O_(6)ceramics but also maintains a high(quality factor(Q)×resonance frequency(f))value while still improving the temperature stability.Typically,great microwave dielectric characteristics when added with 2wt%Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass can be achieved at 1150℃:dielectric constant,ε_(r)=26.1;Q×f=34267 GHz;temperature coefficient of resonance frequency,τ_(f)=-8.7×10^(-6)/℃. 展开更多
关键词 MgTa_(2)O_(6) ceramIC microwave dielectric characteristics glass
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Clay Materials for Ceramics Application from N’Djamena in the Chad Republic: Mineralogical, Physicochemical and Microstructural Characterization
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作者 Ndjolba Madjihingam Djoda Pagore +3 位作者 Jacques Richard Mache Bebbata Warabi Bertin Pagna Kagonbe Patrick Mountapmbeme Kouotou 《Journal of Materials Science and Chemical Engineering》 2024年第2期31-48,共18页
Herein, we report some characteristics of the clayey materials (CMs) collected from Kaliwa (C1), Kabé (C2) and Malo (C3) district in N’Djamena (Chad). Three samples were characterized applying XRF, XRD, FTIR, SE... Herein, we report some characteristics of the clayey materials (CMs) collected from Kaliwa (C1), Kabé (C2) and Malo (C3) district in N’Djamena (Chad). Three samples were characterized applying XRF, XRD, FTIR, SEM. In addition, TGA/DSC were performed to control decomposition/mass loss and show phase transitions respectively of CMs. Geochemical analysis by XRF reveals the following minerals composition: SiO<sub>2</sub> (~57% - 66%), Al<sub>2</sub>O<sub>3 </sub>(~13% - 15%), Fe<sub>2</sub>O<sub>3</sub> (~6% - 10%), TiO<sub>2</sub> (~1% - 2%) were the predominant oxides with a reduced proportion in C1, and (~7%) of fluxing agents (K<sub>2</sub>O, CaO, Na<sub>2</sub>O). Negligible and trace of MgO (~1%) and P<sub>2</sub>O<sub>5</sub> was noted. The mineralogical composition by XRD shows that, C1, C2 and C3 display close mineralogy with: Quartz (~50%), feldspar (~20%) as non-clay minerals, whereas clays minerals were mostly kaolinite (~15%), illite (~5%) and smectite (~10%). FTIR analysis exhibits almost seemingly similar absorption bands characteristic of hydroxyls elongation, OH valence vibration of Kaolinite and stretching vibration of some Metal-Oxygen bond. SEM micrographs of the samples exhibit microstructureformed by inter-aggregates particles with porous cavities. TGA/DSCconfirm the existence of quartz (570˚C to 870˚C), carbonates (600˚C - 760˚C), kaolinite (569˚C - 988˚C), illite (566˚C - 966˚C), MgO (410˚C - 720˚C) and smectite (650˚C - 900˚C). The overall characterization indicates that, these clayey soils exhibit good properties for ceramic application. 展开更多
关键词 Clay Soils Characterization MINERALOGY Physicochemical Properties ceramic Application
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Study on Acoustic Emission Characteristics of Deformation Damage Process of Zirconia Ceramics
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作者 Qingchuan Fu Yushu Lai 《Journal of Materials Science and Chemical Engineering》 2024年第2期61-72,共12页
Zirconia ceramics have become increasingly widely used in recent years and are favored by relevant enterprises. From the traditional dental field to aerospace, parts manufacturing has been used, but there is limited r... Zirconia ceramics have become increasingly widely used in recent years and are favored by relevant enterprises. From the traditional dental field to aerospace, parts manufacturing has been used, but there is limited research on the deformation and damage process of zirconia ceramics. This article analyzes the acoustic emission characteristics of each stage of ceramic damage from the perspective of acoustic emission, and explores its deformation process characteristics from multiple perspectives such as time domain, frequency, and EWT modal analysis. It is concluded that zirconia ceramics exhibit higher brittleness and acoustic emission strength than alumina ceramics, and when approaching the fracture, it tends to generate lower frequency acoustic emission signals. 展开更多
关键词 Zirconia ceramics Acoustic Emission Monitoring Crack Damage
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The B-site ordering in RFe_(0.5)Cr_(0.5)O_(3)ceramics and its effect on magnetic properties
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作者 Li Hou Lei Shi +3 位作者 Liping Yang Yiqiang Liu Zhitao Li Lanxiang Meng 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第10期434-441,共8页
To insight into the B-site ordering in RFe_(0.5)Cr_(0.5)O_(3)ceramics,a series of RFe_(0.5)Cr_(0.5)O_(3)ceramics(R=La,Y,Lu)were synthesized by the sol-gel method,and the structural and magnetic properties were systemi... To insight into the B-site ordering in RFe_(0.5)Cr_(0.5)O_(3)ceramics,a series of RFe_(0.5)Cr_(0.5)O_(3)ceramics(R=La,Y,Lu)were synthesized by the sol-gel method,and the structural and magnetic properties were systemically investigated.By using the Rietveld refinement of all samples,it is found that the structural distortion is increased as the R ionic radius decreases,leading to the weakened interactions between Fe/Cr ions.Moreover,the Fe and Cr are arranged in disorder in LaFe_(0.5)Cr_(0.5)O_(3),but partially ordered in YFe_(0.5)Cr_(0.5)O_(3)and LuFe_(0.5)Cr_(0.5)O_(3),showing an increasing trend of the proportion of ordered domains with the decrease of R ionic radius.Through fitting the temperature-dependent magnetizations,it is identified that the magnetization reversal(MR)in disorder LaFe_(0.5)Cr_(0.5)O_(3)is resulted from the competition between the moments of Cr and Fe sublattices.In the partially ordered YFe_(0.5)Cr_(0.5)O_(3)and LuFe_(0.5)Cr_(0.5)O_(3)ceramics,because of the presence of Fe-O-Cr networks in the ordered domains whose moment is antiparallel to that of Fe-O-Fe and Cr-O-Cr in the disordered domains,the compensation temperature T_(comp)of MR is increased by nearly 50 K.These results suggest that the changing of R-site ions could be used very effectively to modify the Fe-O-Cr ordering,apart from the structural distortion,which has a direct effect on the magnetic exchange interactions in RFe_(0.5)Cr_(0.5)O_(3)ceramics.Then at values of composition where ordered domains are expected to be larger in number as compared to disordered domains and with a weaker structural distortion,one can expect a higher transition temperature Tcomp,providing a different view for adjustment of the magnetic properties of RFe_(0.5)Cr_(0.5)O_(3)ceramics for practical applications. 展开更多
关键词 RFe_(0.5)Cr_(0.5)O_(3)ceramics structural distortion B-site ordering magnetization reversal
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Porous high-entropy rare-earth phosphate(REPO_(4),RE=La,Sm,Eu,Ce,Pr and Gd)ceramics with excellent thermal insulation performance via pore structure tailoring 被引量:1
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作者 Peixiong Zhang Enhui Wang +3 位作者 Jingjing Liu Tao Yang Hailong Wang Xinmei Hou 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第7期1651-1658,共8页
Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high temperatures.In this study,a new porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6)... Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high temperatures.In this study,a new porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4)(HE(6RE_(1/6))PO_(4))ceramics was prepared by combining the high-entropy method with the pore-forming agent method and the effect of different starch contents(0–60vol%)on this ceramic properties was systematically investigated.The results show that the porous HE(6RE_(1/6))PO_(4)ceramics with 60vol%starch exhibit the lowest thermal conductivity of 0.061 W·m^(-1)·K^(-1)at room temperature and good pore structure stability with a linear shrinkage of approximately1.67%.Moreover,the effect of large regular spherical pores(>10μm)on its thermal insulation performance was discussed,and an optimal thermal conductivity prediction model was screened.The superior properties of the prepared porous HE(6RE_(1/6))PO_(4)ceramics allow them to be promising insulation materials in the future. 展开更多
关键词 porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4) ceramics high-entropy strategy pore-forming agent method thermal insulation material thermal conductivity
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Physics-embedded machine learning search for Sm-doped PMN-PT piezoelectric ceramics with high performance
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作者 辛睿 王亚祺 +6 位作者 房泽 郑凤基 高雯 付大石 史国庆 刘建一 张永成 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期81-88,共8页
Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different conce... Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different concentrations of elemental doping are the main methods to modulate their piezoelectric coefficients.The combination of these controllable conditions leads to an exponential increase of possible compositions in ceramics,which makes it not easy to extend the sample data by additional experimental or theoretical calculations.In this paper,a physics-embedded machine learning method is proposed to overcome the difficulties in obtaining piezoelectric coefficients and Curie temperatures of Sm-doped PMN-PT ceramics with different components.In contrast to all-data-driven model,physics-embedded machine learning is able to learn nonlinear variation rules based on small datasets through potential correlation between ferroelectric properties.Based on the model outputs,the positions of morphotropic phase boundary(MPB)with different Sm doping amounts are explored.We also find the components with the best piezoelectric property and comprehensive performance.Moreover,we set up a database according to the obtained results,through which we can quickly find the optimal components of Sm-doped PMN-PT ceramics according to our specific needs. 展开更多
关键词 Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)ceramic physics-embedded machine learning piezoelectric coefficient Curie temperature
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Effect of additives on properties of aluminium titanate ceramics 被引量:7
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作者 姜澜 陈晓燕 +1 位作者 韩国明 孟宇 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第7期1574-1579,共6页
The influence of some additives on bulk density,phase composition,mechanical strength and thermal shock resistance of aluminium titanate (AT) ceramics was investigated.AT ceramics with different additives of MgO,SiO... The influence of some additives on bulk density,phase composition,mechanical strength and thermal shock resistance of aluminium titanate (AT) ceramics was investigated.AT ceramics with different additives of MgO,SiO2 and Fe2O3 were prepared by reaction sintering.Properties of AT ceramics were tested by using Archimedes,three-point bending and thermal cycling tests.It was found that additives of MgO,SiO2 and Fe2O3 or their compound additives are favorable to reduce the porosities of AT,enhance mechanical strength and thermal shock resistance.The role of additives can be rationalized in terms of promotion of sintering process,formation of new phases and influence on lattice constant c of AT ceramics. 展开更多
关键词 aluminium titanate ceramics ADDITIVE bulk density mechanical properties
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Preparation and properties of porous silicon carbide ceramics through coat-mix and composite additives process 被引量:2
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作者 赵宏生 刘中国 +3 位作者 杨阳 刘小雪 张凯红 李自强 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第6期1329-1334,共6页
The core-shell structure silicon-resin precursor powders were synthesized through coat-mix process and addition of Al2O3-SiO2-Y2O3 composite additives.A series of porous silicon carbide ceramics were produced after mo... The core-shell structure silicon-resin precursor powders were synthesized through coat-mix process and addition of Al2O3-SiO2-Y2O3 composite additives.A series of porous silicon carbide ceramics were produced after molding,carbonization and sintering.The phase,morphology,porosity,thermal conductivity,thermal expansion coefficient,and thermal shock resistance were analyzed.The results show that porous silicon carbide ceramics can be produced at low temperature.The grain size of porous silicon carbide ceramic is small,and the thermal conductivity is enhanced significantly.Composite additives also improve the thermal shock resistance of porous ceramics.The bending strength loss rate after 30 times of thermal shock test of the porous ceramics which were added Al2O3-SiO2-Y2O3 and sintered at 1 650 ℃ is only 6.5%.Moreover,the pore inside of the sample is smooth,and the pore size distribution is uniform.Composite additives make little effect on the thermal expansion coefficient of the porous silicon carbide ceramics. 展开更多
关键词 silicon carbide porous ceramic coat-mix composite additives
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In-situ Raman observation on crack tips of Vickers indent in PLZT ceramics 被引量:2
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作者 张飒 程璇 张颍 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第10期2259-2263,共5页
Vickers indentation was introduced into the originally in-plane and out-of-plane poled PLZT ceramics.The Raman spectra were in-situ recorded at selected crack tips before and after the indentations,as well as after th... Vickers indentation was introduced into the originally in-plane and out-of-plane poled PLZT ceramics.The Raman spectra were in-situ recorded at selected crack tips before and after the indentations,as well as after the applications of external electric field.The results show that the changes in Raman intensities of optical modes could be sensitively related to 90° domain switching around the crack tips which are strongly dependent on the directions of original polarization and geometric locations.When the direction of electric field was perpendicular to the direction of original polarization,the 90° domain switching at crack tips of the Vickers indentation on the originally in-plane poled PLZT ceramics caused most significant change in the Raman intensity,which inhibited the crack growth.However,when the direction of electric field was parallel to the direction of original polarization,the growth of crack tips became predominantly without the 90° domain switching,which led to the crack growth. 展开更多
关键词 ferroelectric ceramics domain switching in-situ Raman spectroscopy Vickers indentation
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High temperature oxidation behavior of electroconductive TiN/O′-Sialon ceramics prepared from high titania slag-based mixture 被引量:2
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作者 姜涛 薛向欣 +1 位作者 李哲夫 段培宁 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第12期2638-2643,共6页
The oxidation behavior of electroconductive TiN/O′-Sialon ceramics prepared using high titania slag as main starting material was studied at 1 200-1 300 °C in air. The isothermal and non-isothermal oxidation pro... The oxidation behavior of electroconductive TiN/O′-Sialon ceramics prepared using high titania slag as main starting material was studied at 1 200-1 300 °C in air. The isothermal and non-isothermal oxidation processes were investigated by DTA-TG. Phase compositions and morphologies of the oxidized products were analyzed by XRD, SEM and EDS. The results indicate that the oxidation of TiN and O′-Sialon occurs at about 500 °C and 1 050 °C, respectively. After oxidation at 1 200-1 300 °C, a protective scale that consists of Fe2MgTi3O10, SiO2 and TiO2 is formed on the surface of the materials, which effectively prevents the oxidation process. The formation of a protective scale is relative to TiN content and apparent porosity of the samples, the amount of SiO2 and amorphous phase in the oxidation product. At the initial oxidation stage, the oxidation kinetics of the materials follows perfectly the linear law with the apparent activation energy of 1.574×105 J/mol, and at the late-mid stage, the oxidation of the samples obeys the parabolic law with the apparent activation energy of 2.693×105 J/mol. With the increase of TiN content, mass gain of the materials increases significantly. 展开更多
关键词 TiN/O′-Sialon high titania slag electroconductive ceramics oxidation behavior
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Effects of alcohol additives on pore structure and morphology of freeze-cast ceramics 被引量:1
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作者 曾婧 张妍 +1 位作者 周科朝 张斗 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第3期718-722,共5页
The porous alumina ceramics with lamellar structure were fabricated successfully by freeze casting. The viscosities of alumina slurries, pore structures, porosities and mechanical properties of the sintered ceramics w... The porous alumina ceramics with lamellar structure were fabricated successfully by freeze casting. The viscosities of alumina slurries, pore structures, porosities and mechanical properties of the sintered ceramics were investigated by introducing both types of alcohols as water solidification modifier into the initial slurries, such as ethanol and 1-propanol. With the addition of ethanol or 1-propanol, the viscosities of slurries increased and porosities of sintered ceramics decreased. The compressive strengths of the sintered porous alumina ceramics were improved due to a good connectivity between lamellae with the addition of both types of alcohols. The lowest porosities of 68.52% and 73.72% and highest compressive strengths of 18.2 MPa and 15.0 MPa were obtained by the addition of 30% ethanol in mass fraction and 1-propanol, respectively. 展开更多
关键词 alumina ceramic lameUar porous material ETHANOL 1-propanol
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Dielectric properties and phase transitions of La_2O_3- and Sb_2O_3-doped barium strontium titanate ceramics 被引量:4
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作者 张晨 曲远方 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第11期2742-2748,共7页
The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray d... The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray diffraction method and scanning electron microscope was also employed to observe the surface morphologies. It is found that (La,Sb)-codoped barium strontium titanate ceramics exhibit typical perovskite structure and the average grain size decreases dramatically with increasing the content of Sb2O3. Both La3+ ions and Sb3+ ions occupy the A-sites in perovskite lattice. The dielectric constant and dielectric loss of barium strontium titanate based ceramics are obviously influenced by La2O3 as well as Sb2O3 addition content. The tetragonal-cubic phase transition of La2O3 modified barium strontium titanate ceramics is of second order and the Curie temperature shifts to lower value with increasing the La2O3 doping content. The phase transition of (La,Sb)-codoped barium strontium titanate ceramics diffuses and the deviation from Curie-Weiss law becomes more obvious with the increase in Sb2O3 concentration. The temperature corresponding to the dielectric constant maximum of (La,Sb)-codoped barium strontium titanate ceramics decreases with increasing the Sb2O3 content, which is attributed to the replacement of host ions by the Sb3+ ions. 展开更多
关键词 barium strontium titanate LA2O3 SB2O3 PEROVSKITE ceramics dielectric properties phase transition
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Effects of dwell time during sintering on electrical properties of 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3 ceramics 被引量:1
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作者 程花蕾 周万城 +2 位作者 杜红亮 罗发 朱冬梅 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第10期2984-2988,共5页
The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98(K0.sNa0.5)NbO3-0.02LaFeO3 ceramics (abbreviated as 0.98KNN-0.02LF). All the ceramics sinte... The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98(K0.sNa0.5)NbO3-0.02LaFeO3 ceramics (abbreviated as 0.98KNN-0.02LF). All the ceramics sintered for different dwell time are of pure phase and the peak intensity of the 0.98KNN-0.02LF ceramics becomes stronger with a longer dwell time. Denser microstructures with larger grain size are developed for the sample with a longer dwell time. The maximum dielectric permittivity decreases with increasing the dwell time, and the deteriorative dielectric properties are due to the increasing grain size and the domain wall motion. Ferroelectric properties results indicate that 2Pr value slightly decreases with increasing the dwell time, while the 2Ec value increases. Consequently, the 0.98KNN-0.02LF ceramic sintered at 1150 ℃ for 2 h shows optimum dielectric properties (er=2253 and tan fi〈5%) and ferroelectric properties (2Pr=34.51 gC/cm2 and 2Ec=5.07 kV/mm). 展开更多
关键词 (K0.5Na0.5)NbO3 dwell time dielectric properties ferroelectric property lead-free ceramics
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Design calculation of porous ceramics tube type dew point indirect evaporative cooler 被引量:1
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作者 毛秀明 黄翔 文力 《Journal of Southeast University(English Edition)》 EI CAS 2010年第2期205-208,共4页
To improve the wall surface hydrophilicity of a tube type indirect evaporative cooler,a new method adopting porous ceramics is proposed.This method realizes the combination of porous ceramics and the evaporative cooli... To improve the wall surface hydrophilicity of a tube type indirect evaporative cooler,a new method adopting porous ceramics is proposed.This method realizes the combination of porous ceramics and the evaporative cooling technique.The design calculation of the porous ceramics tube type dew point indirect evaporative cooler are carried out from such aspects as the volumes and status parameters of the primary and secondary air,the cooler structure,the heat transfer of the solid porous ceramic tubes and the resistance of the cooler.The calculation results show that the design is reasonable.Finally,based on the design calculation,the porous ceramics tube type dew point indirect evaporative cooler is successfully manufactured. 展开更多
关键词 tube type indirect evaporative cooler dew point porous ceramics design calculation
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Fabrication of micro-honeycomb ceramics by cloth fabric pore-forming
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作者 伍协 陈振华 +2 位作者 冯延林 刘小磐 李秀莉 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第12期2665-2670,共6页
Micro-honeycomb ceramics were successfully fabricated through brush-coating with cloth fabric as pore-forming agent. The influence of pore-forming agent and slurry’s moisture content on the micro-honeycomb ceramics w... Micro-honeycomb ceramics were successfully fabricated through brush-coating with cloth fabric as pore-forming agent. The influence of pore-forming agent and slurry’s moisture content on the micro-honeycomb ceramics was investigated. The results indicated that micro-honeycomb ceramics made from pore-forming agent cloth fabric with fibre diameter of 100 μm and slurry with 45% (mass fraction) moisture content have the porosity of 65% (volume fraction), bending strength of 24.3 MPa, pore size of about 100 μm, cell wall thickness of about 50 μm and porosity of 1131 pore/cm2. It was suggested that the pore size and the porosity could be adjusted using the pore-forming agent and moisture content of the slurry respectively. 展开更多
关键词 micro-honeycomb ceramics cloth fabric STRENGTH POROSITY
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