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Effect of Bi_2O_3 Additives on Properties of La_(0.7)Ca_(0.3)CrO_3

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Journal of Rare Earths 2005年第1期23卷 36-40页

作者：仲洪海周晓亮刘杏芹孟广耀 Department of Materials Science and Engineering University of Science and Technology of China Hefei 230026 China

sintering characteristics of Ca-doped lanthanum chromite [La(Ca)CrO_3] powder, prepared by gel-casting process were studied by measuring density and the evaluation of micro structural information. Bi_2O_3 is found to be an effective sintering additive for this material. The amount of Bi_2O_3 is altered to investigate Bi_2O_3 effect on the properties of La_(0.7)Ca_(0.3)CrO_3. The amount of 10% (mass fraction) Bi_2O_3 is suitable to increase sinter-ability of La_(0.7)Ca_(0.3)CrO_3. Increased concentration of point defects arising form substitution of Bi in La site is the plausible cause of enhanced sintering. Measurement of electrical conductivity and thermal expansion coefficient indicate that the doping of Bi_2O_3 does not have any significant effect on these properties.

关键词： La_(0.7)Ca_(0.3)CrO_3 gel-casting process sintering aid electrical conductivity rare earths

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

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Nano-Micro Letters 2013年第3期5卷 151-158页

作者： Jung-Hoon Song Myung Geun Jung Hye Won Park Hyung-Tae Lim Fuel Cell Project Research Institute of Industrial Science and Technology (RIST) School of Nano & Advanced Materials Engineering Changwon National University

A Gd-doped ceria（GDC） buffer layer is required between a conventional yttria-stabilized zirconia（YSZ） electrolyte and a La-Sr-Co-Fe-O3（LSCF） cathode to prevent their chemical reaction. In this study,the effect of varying the conditions for fabricating the GDC buffer layer, such as sintering temperature and amount of sintering aid, on the solid oxide fuel cell（SOFC） performance was investigated. A finer GDC powder（i.e., ultra-high surface area）, a higher sintering temperature（1290℃）, and a larger amount of sintering aid（12%） resulted in improved densification of the buffer layer; however, the electrochemical performance of an anode-supported cell containing this GDC buffer layer was poor. These conflicting results are attributed to the formation of（Zr, Ce）O2 and/or excess cobalt grain boundaries（GBs） at higher sintering temperatures with a large amount of sintering aid（i.e., cobalt oxide）. A cell comprising of a cobalt-free GDC buffer layer, which was fabricated using a low-temperature process, had lower cell resistance and higher stability. The results indicate that electrochemical performance and stability of SOFCs strongly depend on fabrication conditions for the GDC buffer layer.

关键词： Solid oxide fuel cell(SOFC) Gd-doped ceria sintering aid Sol-gel spin coating

Microstructure and piezoelectric properties of K_(5.70)Li_(4.07)Nb_(10.23)O_(3)0-added K_(0.5)Na_(0.5)NbO_(3) ceramics

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Journal of Advanced Ceramics 2014年第2期3卷 147-154页

作者： Xuming PANG Jinhao QIU Kongjun ZHU State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mechanical Engineering Nanjing Tech UniversityNanjing 210009China

Lead-free piezoelectric ceramics K_(0.5)Na_(0.5)NbO_(3)-xmol%K_(5.70)Li_(4.07)Nb_(10.23)O_(3)0(x=0-2.5,KNN-xmol%KLN)were prepared by conventional sintering *** phase structure and electrical properties of KNN ceramics were investigated as a function of KLN *** results showed that small amount of KLN introduced into the lattice formed a single phase perovskite *** KLN modification lowered the phase transition temperature of orthorhombic-tetragonal(T_(O-T))and increased the Curie temperature(T_(C)).Some abnormal coarse grains were formed in a matrix when the content of KLN was relatively low(1 mol%).However,normally grown grains were only observed when the sintering aid content was increased to 2 mol%.Proper content of KLN decreased the amount of defects,thus the remanent polarization increased and the coercive field decreased markedly,and the sinterability of the KNN ceramics was simultaneously improved with significant increase of piezoelectric properties.

关键词： ceramics sintering aid phase transformation electrical properties

Effect of LiF on the Optical Transmittance of Magnesium Aluminate Spinel

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Journal of Wuhan University of Technology(Materials Science) 2012年第3期27卷 526-528页

作者：李法荟林红 Department of Materials Science and Engineering Tsinghua University Research Institute of Synthetic Crystals

The effect of LiF as a sintering aid to the optical transparency of magnesium aluminate （MgAl2O4） spinel ceramics is studied. The spinel ceramics is prepared in a process proved to be suitable for commercial production. LiF, in different concentrations ranging from 0-2.5 wt%, is doped into MgAl2O4 powders prepared by sol-gel method. Sample MgAl2O4 ceramic discs are fabricated by ball milling, cold pressing, and hot-pressing, or hot-isostatic-pressing of the powder mixtures. Optical transparency measurements show that, hot-pressed samples exhibit higher transparency when more LiF is added. While for hot-isostatic pressed samples, excessive LiF content leads to a decrease in optical transparency. The optimal LiF doping quantity is suggested for the present technique.

关键词： transperent ceramics spinel liF sintering aid

Effect of TiO_(2)Addition on Properties of Al_(2)O_(3)Ceramics Prepared by Digital Light Printing(DL.P)

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China's Refractories 2023年第1期32卷 35-39页

作者： WANG Rui YANG Daoyuan PAN Yarui YUAN Huiyu CUI Junyan Zhengzhou University Zhengzhou 450000China Porcelain Gold Technology(Henan)Co. Ltd.Dengfeng 452470China

Ceramic slurry of 78 mass%solid loading was prepared using photosensitive acrylic resin and dispersant SP-710 as the liquid phase,Al_(2)O_(3) powder(d50=2.38μm)and TiO_(2) powder additive as the solid *** ceramics were prepared by DLP,sintering for 4 h at 1450,1500,1550 or 1600℃,*** effects of the TiO_(2) addition(0,1%,2%,3%and 5%,by mass)on the properties of the ceramics were *** results show that the addition of TiO_(2) can improve the sintering of Al_(2)O_(3) ceramics,significantly improve the densification,and reduce the sintering *** the optimum TiO_(2) addition of 3%and the optimum sintering temperature of 1600℃,the obtained Al_(2)O_(3) ceramics have shrinkage of 15.7%,15.8%and 23.8%at the x axis,the y axis,and the z axis,respectively,the porosity of 2.4%,the bulk density of 3.74 g·cm-3 and the three-point bending strength of 251.1 *** with the undoped alumina ceramics,the doped alumina ceramic has increased bulk density by 0.56 g·cm-3,decreased apparent porosity from 20.2%to 2.4%,and the three-point bending strength increases by 2.5 ***,the density and the strength of DLP prepared ceramics can be improved effectively by adding an appropriate amount of TiO_(2),and the performance of the DLP prepared ceramics is close to that of the pressed ***,it is hopeful to apply DLP in refractories field.

关键词： digital light printing alumina ceramics strength bulk density sintering aid

Impact of Functional Additives on Properties of Al_2O_3-C Slide Gate Plate Refractories

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China's Refractories 2017年第3期26卷 19-22页

作者： Ali Baghaei Mehdi Naeemi Mehrgodaz Refractories Company

Al2O3-C refractories are widely used as functional elements like nozzles, well blocks, sliding gate plates and stoppers in the continuous casting process of steel production. Application of silicon as a metallic agent in Al2O3-C slide gate plate production is usual. In fact, a non-oxide bond can be generated due to the reaction between silicon and carbon under reducing atmosphere in the plate matrix. This non-oxide bond can enhance the mechanical strength and abrasion resistance. In order to improve the mechanical and thermo-mechanical properties, functional additives can be aimed to lower the sinte- ring temperature and tailor the microstructure. For this reason, the effect of a special solid state sintering aid addition on the microstructure and thermo-mechanical properties of Al2O3-C slide gate plates in the presence of Si as a metallic component has been investigated. Two types of specimens were pressed at 150 MPa, tempered at 200 ℃ and fired in coke bed at 1 400 ℃ , respectively. Physical （ BD and AP ） , mechanical （ CCS and MOR ） and thermo-mechanical （ HMOR ） properties were determined; in addition, phase composition was characterized by X-ray diffraction analysis （ XRD ） and microstructure of specimens was investigated by field emission scanning electron microscopy （FESEM）. Results have shown that the addition of sintering aid increased the generation of cation vacancy in Al2O3 structure which enhanced the cation diffusion and densification process ; consequently, CCS, MOR and HMOR of specimens increased drasticallywhile bulk density and apparent porosity remained un- changed.

关键词： alumina carbon refractories microstructure mechanical properties sintering aid silicon carbide