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Substituent Influence of Yttria by Gadolinia on the Tetragonal Phase Stability for Y_2O_3-Ta_2O_5-ZrO_2 ceramics at 1300℃

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Journal of Materials Science & Technology 2014年第4期30卷 381-386页

作者： Xiaoqing Niu Min Xie Fen Zhou Rende Mu Xiwen Song Shengli An Inner Mongolia Key laboratory of advanced ceramics and Device School of Materials and MetallurgyInner Mongolia University of Science and Technology Beijing Institute of Aeronautical Materials

The influences of equimolar substitution of yttria by gadolinia on the phase constituent and stability for Y203- Ta2Os-Zr02 ceramics have been investigated. The ceramics with the Gd content lower than 8 tool% exhibit pure tetragonal phase as well as high tetragonal phase stability. However, the high Gd containing ceramics consist of t-Zr02, m-Zr02 and monoclinic GdTa04 and show complicated phase evolution behaviors. The fractions of monoclinic Zr02 and GdTa04 increase with increasing Gd content, indicating that the excessive substitution of Gd for Y results in a reduction in the tetragonal phase stability. In addition, the lower Gd containing ceramics show an almost invariable tetragonality, while the higher Gd containing ceramics reveal a composition-dependent tetragonality. Accordingly, an association of the tetragonal phase stability and tetragonality with the Gd concentration is established, which provides us a clue to understand the phase stability of these ceramics.

关键词： ceramics Zr02 X-ray diffraction Thermal stability

Cutability Evaluation of Oxide ceramics Containing Rare Earth Phosphates

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Journal of Rare Earths 2003年第S1期21卷 93-98页

作者：于爱兵钟利军刘家臣邱世鹏田欣利 State Education Ministry Key laboratory of advanced ceramics & Machining Technology Tianjin University Institute of Armored Force

Cutabilities of machinable ceramics were evaluated and classified based on fuzzy comprehensive evaluation theory. Ce-ZrO_2/CePO_4 composites were fabricated, measured,machined and evaluated to research cutability of oxide ceramics containing rare earth phosphates. A comprehensive evaluation method was proposed for cutability assessments of machinable ceramics based on fuzzy set theory. Mechanical property parameters of composites were selected as alternative set. Five grades were chosen for the cutability evaluation of machinable ceramics. Fuzzy matrix was calculated for an alternative according to membership function. Then cutability grade of material was determined through fuzzy operation. Prepared Ce-ZrO_2/CePO_4 composites were classified as three cutability grades according to comprehensive evaluation results,which was consistent with the material removal rates in drilling experiments. The cutability grades of Ce-ZrO_2/CePO_4 composites increase with the proportions of CePO_4. There are obvious ductile machining marks on Ce-ZrO_2/CePO_4 composites drilling surfaces. Moreover,cutabilities of other oxides containing LaPO_4 were studied. The evaluation method for material cutability establishes the relation between material properties and machining technologies,and can provide one new material design method.

关键词： ceramics fuzzy evaluation cutability rare earths

巨噬细胞负载Fe_(3)O_(4)@PLGA纳米颗粒触发智能催化功能杀死多重耐药大肠杆菌

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Engineering 2024年第3期34卷 174-186页

作者： Jieni Fu Xiangmei Liu Zhaoyang Li Yufeng Zheng Yu Zhang Hui Jiang Yanqin Liang Shengli Zhu Zhenduo Cui Shuilin Wu Key laboratory of advanced ceramics and Machining Technology of the Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjin 300401China School of Materials Science and Engineering Peking UniversityBeijing 100871China School of Health Sciences and Biomedical Engineering Hebei University of TechnologyTianjin 300401China Department of Orthopedics Guangdong Provincial People’s HospitalGuangdong Academy of Medical SciencesGuangzhou 510080China

Infections with multidrug-resistant(MDR)Gram-negative bacteria,such as MDR Escherichia coli(***),remain a challenge due to the lack of safe antibiotics and high fatality rates under anti-infection *** work presents a form of biomimetic intelligent catalysis inspired by the selective biocatalytic property of macrophages(MΦs),consisting of an intelligent controlling center(a living MΦ)and a Fenton reaction catalyst(Fe_(3)O_(4)@poly(lactic-co-glycolic acid)(PLGA)nanoparticles)for killing MDR *** without harming normal *** MΦ-Fe_(3)O_(4)@PLGA particles(i.e.,the intelligent catalysis particles)exhibit selective biocatalysis activity toward MDR *** by producing H_(2)O_(2) and lipid droplets(LDs).This process activates the lipid metabolism and glycan biosynthesis and metabolism pathways based on the result of RNA sequencing data *** H_(2)O_(2) further reacts with Fe_(3)O_(4)@PLGA to form highly toxic hydroxyl radicals(·OH),while the LDs contain antimicrobial peptides and can target MDR *** highly toxicOH and antimicrobial peptides are shown to combat with MDR ***,such that the antibacterial efficiency of the MΦ-Fe_(3)O_(4)@PLGA particles against MDR *** is 99.29%±0.31%in *** importantly,after several passages,the intelligent catalysis function of the MΦ-Fe_(3)O_(4)@PLGA particles is well ***,the concept of biomimetic intelligent catalysts displays potential for treating diseases other than infections.

关键词： Multidrug-resistant Escherichia coli Macrophage-Fe_(3)O_(4)@PLGA particles Biomimetic intelligent catalysis

High-strength porous alumina ceramics prepared from stable wet foams

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Journal of advanced ceramics 2021年第4期10卷 852-859页

作者： Linying WANG Liqiong AN Jin ZHAO Shunzo SHIMAI Xiaojian MAO Jian ZHANG Juan LIU Shiwei WANG College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 201306China State Key laboratory of High Performance ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Key laboratory of Transparent and Opto-functional advanced Inorganic Materials Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China

Porous ceramics have been widely used in heat insulation,filtration,and as a catalyst *** with high porosity and high strength are desired;however,this high porosity commonly results in low strength *** this study,porous alumina with high porosity and high strength was prepared by a popular direct foaming method based on particle-stabilized wet foam that used ammonium polyacrylate(PAA)and dodecyl trimethyl ammonium chloride(DTAC)as the dispersant and hydrophobic modifier,*** effects of the dispersant and surfactant contents on the rheological properties of alumina slurries,stability of wet foams,and microstructure and mechanical properties of sintered ceramics were *** microstructure of porous ceramics was regulated using wet foams to achieve high *** a given PAA content,the wet foams exhibited increasing stability with increasing DTAC *** most stable wet foam was successfully obtained with 0.40 wt%PAA and 0.02 wt%*** corresponding porous alumina ceramics had a porosity of 82%,an average grain size of 0.7μm,and a compressive strength of 39 ***,for a given DTAC content,the wet foams had decreasing stability with increasing PAA content.A possible mechanism to explain these results is analyzed.

关键词： porous ceramic alumina dispersant hydrophobic modifier compressive strength

Ultra-high-temperature application of MXene: Stabilization of 2D Ti_(3)C_(2)T_(x) for cross-scale strengthening and toughening of 3D TiC

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Journal of advanced ceramics 2024年第1期13卷 1-10页

作者： Lu Liu Guobing Ying Quanguo Jiang Dong Wen Peng Wang Meng Wu Ziying Ji Yongting Zheng Xiang Wang Department of Materials Science and Engineering College of Mechanics and MaterialsHohai UniversityNanjing 211100China Key laboratory of Superlight Materials&Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin 150001China Shenzhen Key laboratory for advanced Materials School of Materials Science and EngineeringHarbin Institute of Technology(Shenzhen)Shenzhen 518055China Center for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150001China

Transition metal carbide/nitride cores within MXenes make them considerably useful for ultra-high-temperature ***,extensive research on Ti_(3)C_(2)T_(x) MXene has revealed its tendency to undergo a phase transition to TiCy at temperatures above 800℃due to high activity of a superficial Ti atomic ***,spark plasma sintering of Ti_(3)C_(2)T_(x) and TiC is performed to prevent the Ti_(3)C_(2)T_(x) phase transition at temperatures up to 1900℃through the fabrication of composites at a pressure of 50 *** a focused ion beam scanning electron microscope to separate layered substances in the composites and examining selected area diffraction spots in a transmission electron microscope enabled identification of non-phase-transitioned ***-principles calculations based on density functional theory indicated the formation of strong chemical bonding interfaces between Ti_(3)C_(2)T_(x) and TiC,which imposed a stability constraint on the Ti atomic layer at the Ti_(3)C_(2)T_(x) *** performance tests,such as three-point bending and fracture toughness analysis,demonstrated that the addition of Ti_(3)C_(2)T_(x) can effectively improve the cross-scale strengthening and toughening of the TiC matrix,providing a new path for designing and developing two-dimensional(2D)carbides cross-scale-enhanced three-dimensional(3D)carbides with the same elements relying on a wide variety of MXenes.

关键词： MXene ultra-high-temperature phase stability interface bonding cross-scale strengthening and toughening structural ceramic composites

N-doped hollow carbon nanospheres embedded in N-doped graphene forming a three-dimensional interconnected layered porous support loaded with palladium nanoparticles as an efficient electrocatalyst for formic acid oxidation

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新型炭材料(中英文) 2024年

作者： FANG Yue YANG Fu-kai QU Wei-li DENG Chao WANG Zhen-bo Key laboratory of Photochemical Biomaterials and Energy Storage Materials Shenzhen Key laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advance Technology of Ceramics Guangdong Research Center for Interfacial Engineering of Functional Materials College of Materials Science and Engineering Shenzhen University MIIT Key laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical Engineering State Key Lab of Urban Water Resource and Environment Harbin Institute of Technology College of Chemistry and Chemical Engineering Harbin Normal University No.1 Normal University South Road

The efficient electrocatalysts with low cost, high activity and good durability plays a crucial role in the application of direct formic acid fuel cells. Herein, Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCN) embedded in Ndoped graphene (NG) with three-dimensional (3D) layered porous configuration by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Owing to the unique 3D interconnected layered porous configuration doped with nitrogen atoms, Pd/NHCN@NG catalyst with smaller Pd nanoparticle size shows large catalytic active surface area, superior electrocatalyticactivity,highsteady-statecurrentdensity,strongabilitytoresistCOpoisoning,farsurpassingthoseofconventionalPd/C,Pd/NG,andPd/***/GOratio,itisfoundthatwhenthe HCN/GO mass ratio is 1∶1, Pd/NHCN@NG catalyst has the most outstanding performance in catalytic oxidation of formic acid,with an activity 4.21 times that of Pd/C. This work has developed a superior carbon-based support material for electrocatalysts, which brings broad application prospects for the development of fuel cells.

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Sintering effect on ageing behavior of rare earths (Pr_6O_(11)-Er_2O_3-Y_2O_3 )-doped ZnO varistor ceramics

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Journal of Rare Earths 2012年第10期30卷 1028-1033页

作者： Choon-Woo Nahm Semiconductor ceramics laboratory Department of Electrical Engineering Dongeui University

The electrical properties and ageing behavior of the rare earths （Pr6O11-Er2O3-Y2O3）-doped ZnO varistor ceramics were systematically investigated at sintering temperature range of 1335-1350°C. With an increase in the sintering temperature, the sintered density increased from 5.41 to 5.64g/cm3 and the average grain size increased from 5.8 to 7.9μm. The varistor properties and ageing behavior were significantly affected by small sintering temperature range of 1335-1350°C. The breakdown field noticeably decreased from 5767 to 3628V/cm with an increase in the sintering temperature. The varistor ceramics exhibited the highest nonlinear coefficient （43.2） at the sintering temperature of 1340°C. The varistor ceramics sintered at 1350°C exhibited a surprisingly excellent stability by exhibiting 0.3% in the variation rate of the breakdown field and 0.3% in the variation rate of the nonlinear coefficient for ageing stress of 0.95 E1mA/150°C/24 h.

关键词： sintering rare earths nonlinear properties ageing varistors

Effect of sintering temperature on microstructure and varistor properties of Zn-V-O-based ceramics incorporated with Mn-Nb-Tb

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Transactions of Nonferrous Metals Society of China 2015年第12期25卷 4040-4045页

作者： C.W.NAHM Semiconductor ceramics laboratory Department of Electrical Engineering Dongeui University

The effect of sintering temperature on microstructure and varistor properties of Zn-V-O-based ceramics incorporated with Mn-Nb-Tb was investigated. The results showed that the increase of sintering temperature in the range from 875 to 950 °C decreased the densities of sintered pellets in the range of 5.55 to 5.45 g/cm3 and increased the average grain size in the range of 4.1 to 8.8 ？m. The breakdown field decreased noticeably from 7443 to 1064 V/cm with increasing sintering temperature from 875 to 950 °C. The varistor ceramics sintered at 900 ？C exhibited nonlinear properties, with 49.4 in the nonlinear coefficient and 0.21 m A/cm2 in the leakage current density. The dielectric constant increased greatly from 440.1 to 2197.2 with increasing sintering temperature from 875 to 950 °C; however, the dissipation factor exhibited a fluctuation between 0.237 and 0.5. These ceramic compositions and sintering conditions can be applied to the development of advanced multiplayer varistors with silver as an inner electrode.

关键词： Zn-V-O-based ceramics Mn-Nb-Tb sintering varistor properties dielectric characteristics varistor

Sintering of transparent Nd:YAG ceramics in oxygen atmosphere

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Journal of Rare Earths 2013年第2期31卷 153-157页

作者：黄毅华江东亮张景贤林庆玲黄政仁 The State Key laboratory of High Performance ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of Sciences

Yttrium aluminum garnet （YAG） transparent ceramics were fabricated by sintering at oxygen atmosphere. Tetraethyl orthosilicate （TEOS） was added as the sintering additive to control the grain growth and densification. Pores were eliminated clearly at temperature lower than 1700oC, while grain size was around 3 μm. The in-line transmittance was 80% at 1064 nm when samples were sintered at 1710oC. The effect of TEOS was studied in oxygen atmosphere sintering for Nd：YAG transparent ceramics. At higher temperature like 1710oC, the grain growth mechanism was solute drag, while at 1630 and 1550 oC the grain growth was controlled by liquid phase sintering mechanism. And 0.5 wt.% TEOS was the best adding content for Nd：YAG sintered in oxygen atmosphere.

关键词： transparent ceramics YAG oxygen atmosphere sintering rare earths