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Enhancing microstructural properties of alumina ceramics via binary sintering aids

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Journal of Central South University 2021年第12期28卷 3705-3713页

作者： HU Yan-jun YIN Zi-qiang GONG Yu-bo YANG Zhi-gang YANG Zhan-ping LIANG Yin-chun DONG De-jun ZHAO Jin-jin School of Materials Science and Engineering Hebei Key Laboratory of Material Near Net Forming TechnologyHebei University of Science and TechnologyShijiazhuang 050018China School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China Institute of Materials for Energy Conversion Shijiazhuang Tiedao UniversityShijiazhuang 050043China Nantong ZhuhaiKunming Cellulose Fibers Company Technical CenterNantong 226008China

alumina ceramics are widely used in many fields such as cutting tools,laser shock materials,roadbed board and ***,Al_(2)O_(3)ceramics are prepared by a low-cost pressureless sintering technology,using the binary sintering aids of MgO and SiO_(2).The effects of sintering temperature and the ratio of binary sintering aids on the mechanical properties and microstructure of Al_(2)O_(3)ceramics are investigated.A spinel second phase(MgAl_(2)O_(4))is found out by the analysis of the results of XRD and EDS when MgO and SiO_(2)are introduced in the *** optimum properties are found when MgO content is 20 wt.%based on the total sintering aids and the sintering temperature is 1550℃.The bending strength and the bulk density reach a maximum value of 314 MPa and 3.73 g/cm^(3),*** addition of appropriate amount of SiO_(2)makes the formation of liquid phase sintering and the removal of large ***,a small amount of magnesium oxide doping has an effect on the grain refinement from the microstructure of the ***,it is believed that MgO and SiO_(2)are the ideal sintering aids for promoting the densification and property of alumina ceramics.

关键词： alumina ceramics binary sintering aids mechanical properties microstructure

Microstructure and mechanical properties of 3D printed ceramics with different vinyl acetate contents

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Rare Metals 2021年第11期40卷 3241-3250页

作者： He Li Yong-Sheng Liu Yan-Song Liu Qing-Feng Zeng Jing-Jing Liang Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China NPU-SAS Joint Research Center of Advanced ceramics Northwestern Polytechnical UniversityXi’an 710072China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Stereolithography(SL)-based three-dimensional(3D) printing technique is an efficient method for the fabrication of alumina *** alumina slurry is difficult to obtain due to the barrier between hydrophilic alumina and oleophilic *** not only requires that the ceramic slurry possessed low viscosity and uniformity,but also requires that the slurry could complete the photocuring *** this study,vinyl acetate was added in the ceramic slurry as a bridge to connect alumina and resin,and the effects of vinyl acetate content on the microstructure and mechanical properties of the alumina ceramics were systematically *** results showed that the alumina ceramics were composed of three types of particles which included large aggregates,individual particles,and long-columnshaped *** shrinkage,bulk density,and crystallite size of the ceramics increased with the increase in vinyl acetate *** open porosity decreased with the increase in vinyl acetate *** flexural strength of the ceramics first increased and subsequently decreased with the increase in vinyl acetate *** shrinkage in Z direction was much greater than that in X or Y *** on the above results,the optimum vinyl acetate content for alumina slurry was 10 wt%,which resulted in sintered ceramic with the shrinkage of 15.6% in X direction,13.5% in Ydirection,21.9% in Z direction,bulk density of 1.9 g·cm^(-3),open porosity of 50.1%,and flexural strength of 24.4 *** sintered ceramics satisfy the requirement of alumina ceramic cores.

关键词： Stereolithography alumina ceramics Vinyl acetate Microstructure Mechanical properties

Effect of sintering temperature in argon atmosphere on microstructure and properties of 3D printed alumina ceramic cores

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Journal of Advanced ceramics 2020年第2期9卷 220-231页

作者： He LI Yongsheng LIU Yansong LIU Qingfeng ZENG Kehui HU Zhigang LU Jingjing LIANG Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’anShaanxi 710072China NPU-SAS Joint Research Center of Advanced ceramics Northwestern Polytechnical UniversityXi’anShaanxi 710072China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

alumina ceramics with different sintering temperatures in argon atmosphere were obtained using stereolithography-based 3D *** effects of sintering temperature on microstructure and physical and mechanical properties were *** results show that the average particle size,shrinkage,bulk density,crystallite size,flexural strength,Vickers hardness,and nanoindentation hardness increased with the increase in sintering temperature,whereas the open porosity decreased with increasing sintering *** change was observed in phase composition,chemical bond,atomic ratio,and surface *** the sintered samples,the shrinkage in Z direction is much greater than that in X or Y *** optimum sintering temperature in argon atmosphere is 1350℃with a shrinkage of 3.0%,3.2%,and 5.5%in X,Y,and Z directions,respectively,flexural strength of 26.7 MPa,Vickers hardness of 198.5 HV,nanoindentation hardness of 33.1 GPa,bulk density of 2.5 g/cm^3,and open porosity of 33.8%.The optimum sintering temperature was 70℃higher than that sintering in air atmosphere when achieved the similar properties.

关键词： sintering temperature argon atmosphere alumina ceramics microstructure stereolithography

PROGRESSIVE FRAGMENT MODELING OF FAILURE WAVE IN ceramics UNDER PLANAR IMPACT LOADING

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Applied Mathematics and Mechanics(English Edition) 2006年第2期27卷 215-220页

作者：姚国文刘占芳黄培彦 School of Civil Engineering and Architecture Chongqing Jiaotong University Chongqing 400074 P. R. China Department of Engineering Mechanics Chongqing University Chongqing 400044 P. R. China College of Traffic and Communications South China University of Technology Guangzhou 510640 P. R. China

Polycrystalline ceramics have heterogeneous meso-structures which result in high singularity in stress distribution. Based on this, a progressive fragment model was proposed which describes the failure wave formation and propagation in shocked ceramics. The governing equation of the failure wave was characterized by inelastic bulk strain with material damage and fracture. And the inelastic bulk strain consists of dilatant strain from nucleation and expansion of microcracks and condensed strain from collapse of original pores. Numerical simulation of the free surface velocity was performed in good agreement with planar impact experiments on 92.93% aluminas at China Academy of Engineering Physics. And the longitudinal, lateral and shear stress histories upon the arrival of the failure wave were predicted, which present the diminished shear strength and lost spall strength in the failed layer.

关键词： failure wave progressive fragment model alumina ceramics heterogeneous meso-structures plate impact experiment

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