检索结果-南通市图书馆

Effects of rare earth oxides on microstructures and thermo-physical properties of hafnia ceramics

Journal of Materials Science & Technology 2021年第13期72卷 144-153页

作者： Chun Li Chaolong Ren Yue Ma Jian He Hongbo Guo School of Materials Science and Engineering Beihang UniversityBeijing100191China Key Laboratory of High-temperature Structural Materials&Coatings Technology(Ministry of Industry and Information Technology) Beihang UniversityBeijing100191China

Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite(F)structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore(P)and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m^(-1)K^(-1)at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients(TECs)of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3×10^(-6)K^(-1) in temperature range between 200-1200℃.

关键词： Rare earth oxides multi-doped hafnia Fluorite Pyrochlore Sintering resistance thermo-physical properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of rare earth doping on thermo-physical properties of lanthanum zirconate ceramic for thermal barrier coatings

引用

Journal of Rare Earths 2008年第6期26卷 770-774页

作者：周宏明易丹青 School of Materials Science and Engineering Central South University

The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal diffusivity methods were used to analyze thermal expansion coefficient （TEC）, specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2（Zr1.8Ce0.2）2O7 and La1.7（DyNd）0.15（Zr0.8Ce0.2）2O7 had higher TEC than La2Zr2O7 and La1.7Dy0.3Zr2O7. La2（Zr1.8Ce0.2）2O7, La1.7Dy0.3Zr2O7, and La1.7（DyNd）0.15（Zr0.8Ce0.2）2O7 had lower thermal conductivity than undoped La2Zr2O7. The Dy2O3, Nd2O3, and CeO2 codoped composition showed the lowest thermal conductivity and the highest TEC. thermo-physical results also indicated that TEC of rare earth oxide doped La2Zr2O7 ceramic was slightly higher than that of conventional ZrO2-8Wt.% Y2O3 （8YSZ）, and its thermal conductivity was lower than that of 8YSZ.

关键词： lanthanum zirconate thermal barrier coatings thermo-physical properties pyrochlore oxides rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

thermo-physical properties of rubber seed useful in the design of storage structure

引用

International Journal of Agricultural and Biological Engineering 2012年第2期5卷 62-66页

作者： A.Fadeyibi Z.D.Osunde Department of Agricultural and Bioresources Engineering Federal University of TechnologyMinnaNigeria

This study was carried out to determine the thermo-physical properties of rubber seed in the moisture range of 9.1%to 14.8%(w.b.).The length,width,thickness,measured surface area,bulk density and true density increased with increasing moisture content with high coefficients of determination(significant at p<0.05).Their optimum values at 14.8%moisture content were 17.00 mm,11.94 mm,8.26 mm,285.20 mm^(2),295.00 kg/m^(3) and 470.67 kg/m^(3),respectively.The angle of repose increased as moisture content increased with low coefficient of determination and has optimum value of 28.81°at 14.8%moisture content.The specific heat capacity and thermal conductivity decreased linearly while thermal diffusivity increased exponentially with an increase in moisture content(significant at p<0.05).The optimum values of specific heat capacity,thermal conductivity and diffusivity at 14.8%moisture content were 55.84 kJ/(kg.K),0.032 W/(m.K)and 1.93×10^(-9) m^(2)/s,respectively.The results are essential in the design of storage structure for rubber seed.

关键词： thermo-physical properties rubber seed storage specific heat capacity bulk density storage structure design

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Unsteady Heat Transfer in Bilayer,and Three-Layer Materials

引用

Fluid Dynamics & Materials Processing 2023年第4期19卷 977-990页

作者： Toufik Sahabi Smain Balaska Physics Department Faculty of SciencesUniversity of Saida Dr.Moulay TaharSaida20000Algeria Theoretical Physics Laboratory University of Oran-1-Ahmed Ben BellaOran31000Algeria

The heat transfer equation is used to determine the heat flow by conduction through a composite material along the real axis.An analytical dimensionless analysis is implemented in the framework of a separation of variables method(SVM).This approach leads to an Eigenvalues problem that is solved by the Newton’s method.Two types of dynamics are found:An unsteady condition(in the form of jumps or drops in temperatures depending on the considered case),and a permanent equilibrium(tending to the ambient temperature).The validity and effectiveness of the proposed approach for any number of adjacent layers is also discussed.It is shown that,as expected,the diffusion of the temperature is linked to the ratio of the thermo-physical properties of the considered layers and their number.

关键词： Heat transfer conduction eigen values composite materials thermo-physical properties

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Synthesis of a Fully Biobased Polyfunctional Vinyl Oligomer and Their UV Cured Films Prepared via Thiol-ene Coupling

引用

Journal of Renewable Materials 2019年第8期7卷 795-805页

作者： Changqing Fu Jiahui Wang Lie Chen Liang Shen Department of Polymer and Coating Jiangxi Science&Technology Normal UniversityNanchangChina Jiangxi Engineering Laboratory of Waterborne Coating NanchangChina

In this paper,a fully bio-based vinyl oligomer with high functionalities was successfully prepared from rapeseed oil by three modification steps:epoxidation of rapeseed oil,solvent-free and catalyst-free ring opening by 10-undecylenic acid followed by esterification with 10-undecenoyl chloride.Then,the renewable polymers were prepared by photo-polymerization of these modified vegetable oils with typical thiol monomers:pentaerythritol tetrakis(3-mercaptopropionate),pentaerythritol tris(3-mercaptopropionate)and 1,2-ethanedithiol.The synthesis of the vinyl oligomer was monitored by nuclear magnetic resonance and Fourier-transform infrared spectroscopy.The average number of the carbon-carbon double bonds of the resulting vinyl oligomer is high to be 7.2.The kinetic of thiol-ene photo-polymerization of vegetable oil-based vinyl oligomer was studied by FTIR-ATR analyses.In addition,the thermo-physical properties,thermal stability and solvent resistance of these UV cured films were characterized.The polymers from 1,2-ethanedithiol exhibit higher gel content,storage modulus and glass transition temperature than those from other thiol monomers due to the high crosslinking densities of the resulting polymers.All polymers show excellent thermal stability up to 290oC.The resulting polymers exhibit thermo-physical properties,excellent water resistance and thermals stability,which is promising to find application in coatings and adhesives.

关键词： Vegetable oil photo-polymerization thermo-physical properties thermal stability

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：