检索结果-内蒙古大学图书馆

Sintering behavior and microwave dielectric properties of Ba1+x(Mg1/3Nb2/3)O3 ceramics

Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2008年第8期30卷 27-29页

作者： Tian, Zhong-Qing Zhao, Wei-Lin Yu, Hong-Tao Chen, Wei-Ling School of Materials Science and Engineering Chongqing Institute of Technology Chongqing 400050 China State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Sintering behavior, microstructure and microwave dielectric properties of Ba1+x(Mg1/3Nb2/3)O3 (-0.01 [less-than or equal to] x [less-than or equal to] 0.01) were investigated. An improvement of the degree of 1:2 ordering and sinterability was found in Ba-deficient Ba(Mg1/3 Nb2/3)O3 because there existed Ba vacancies. Excessive Ba inhibits the sintering and the degree of 1:2 ordering. It was proposed that excessive Ba exist in grain boundary and inhibit the movement of grain boundary. Therefore, the sintering was restrained. Ba-deficiency had little effect on dielectric constant of Ba(Mg1/3Nb2/3)O3 ceramics. With Ba-deficiency increasing, Qf value decreased drastically.

关键词： Ba(Mg1/3Nb2/3)O3 Microwave dielectric ceramic Ordering Sinterability

来源：评论

学校读者我要写书评

暂无评论

Thermal Stress Calculation and Fabrication of 6063 Al/60SiC‐35Al‐5Si Graded materials by Spark Plasma Sintering

引用

AIP Conference Proceedings 2008年第1期973卷 844-849页

作者： Zhang Dongming Zhang Lianmeng Gu Xiaofeng Chen Fei State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P.R. China

The high intensity of thermal stress was generated during fabrication of 6063 aluminum/60SiC‐35Al‐5Si double‐layer material. In order to decrease the thermal stress, graded materials of Al/60SiC‐35Al‐5Si was fabricated by spark plasma sintering. The CTE in the graded layer was controlled by SiC fraction and particle sizes. The calculation results indicate that the net stress of more than 800 MPa was generated in the double‐layer materials, but it decreased to 170 MPa or less in the graded materials. So the stability can be guaranteed in the graded composites. The graded layers also have the potential for high thermal conductivity, more than 180W/Mk for every layer, which satisfies the application.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Structure and microwave dielectric properties of a new niobate Ba3Nd2Ti2 Nb2O15

引用

Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2008年第1期30卷 28-31页

作者： Hu, Chang-Zheng Zhu, Wen-Feng Wu, Bo-Lin Zhang, Gui-Ling Key Lab. of Nonferrous Materials and New Processing Technology Guilin University of Technology Guilin 541004 China Guangxi Key Lab. for Advanced Materials and New Preparation Technology Guilin 541004 China

A new niobate Ba3Nd2Ti2 Nb2O15 was synthesized by high temperature solid state reaction in the BaO-Nd2O3-TiO2- Nb2O5 system. The chemical compositions, crystal structure, microstructure, and microwave dielectric properties of the new compound were characterized. Ba3Nd2Ti2 Nb2O15 crystallizes in trigonal system with space group P3 ml (164) and lattice constants a=5.6532(1) A, c=11.6117(2) A, V=321.377(6) A3, Z=1. The Ba3Nd2Ti2 Nb2O15 ceramic exhibits a high dielectric constant of 40.1, high quality factors (Q) 3390 (at 5.7542 GHz), and low temperature variation of resonant frequency (τf)+12 × 10-6 K-1. Ba3Nd2Ti2 Nb2O15 might be a suitable candidate of high εr microwave dielectric ceramics.

关键词： Dielectric properties New niobate Perovskite-like structure

来源：评论

学校读者我要写书评

暂无评论

Optical properties of pulsed laser deposited K3Li2Nb5O15 thin films

引用

Rengong Jingti Xuebao/Journal of Synthetic Crystals 2008年第2期37卷 297-300页

作者： Zhan, Zu-Sheng Gong, Yan-Sheng Wang, Chuan-Bin Shen, Qiang Zhang, Lian-Meng State Key Lab. of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology Wuhan 430070 China School of Materials Science and Chemical Engineering China University of Geosciences Wuhan 430074 China

Potassium lithium niobate (KLN:K3Li2Nb5O15) thin films have been deposited on quartz glass by pulsed laser deposition (PLD) technique using a stoichiometric KLN target, which was prepared by solid reaction with K2CO3, Li2CO3, and Nb2O5 powders as starting materials. X-ray diffraction (XRD) and Raman studies have revealed that tetragonal tungsten-bronze-type structure of KLN films with (310) preferred orientation could be achieved at the substrate temperature of 700°C and the oxygen partial pressure of 10 Pa. The average transmittance of as-deposited thin films in the visible range was nearly 90%.

关键词： Ferroelectric thin films

来源：评论

学校读者我要写书评

暂无评论

Preparation of Silicon Nitride Multilayer Ceramic Radome Material and Optimal Design of the Wall Structure

引用

AIP Conference Proceedings 2008年第1期973卷 889-894页

作者： Chen Fei Shen Qiang Zhang Lianmeng State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P. R. China

A study of silicon nitride ceramic radomes, which includes preparation of the material and optimal design of the radome wall structure, is presented in this paper. Multilayer radome wall structure with high dielectric constant skins and a low dielectric constant core layer is used for broadband application. As a candidate material for both the skins and core layer, silicon nitride ceramics of controlled dielectric constant in the range 3.0∼7.5 were prepared by adding different content of sintering aids such as magnesia, alumina, silica and zirconium phosphate binder and choosing suitable sintering methods. A computer aided design (CAD) for the wall structure of silicon nitride multilayer ceramic radome based on microwave equivalent network method is carried out according to design requirements. By optimizing the thickness of skins and core layer, the power transmission efficiency of such a multilayer Si3N4 ceramic radome is calculated. The calculated results suggest that when the dielectric constant of skins lies in the range 6∼7.5 and core layer in the range 3.5∼4, the power transmission efficiency is above 85% with frequency of 2∼18 GHz while the thickness of skins is less than 0.03λ and the thickness ratio of skins to core layer is less than 1:15.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Fabrication of Silicon Nitride Ceramics with Pore Gradient Structure

引用

AIP Conference Proceedings 2008年第1期973卷 3-8页

作者： Zhang Lian‐meng Chen Fei Shen Qiang Yan Fa‐qiang State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P. R. China

In the present study, Si3N4 ceramics with pore gradient structure were prepared by spark plasma sintering (SPS) technique. Silicon nitride ceramics with different controlled porosities were prepared by using ZrP2O7 as a binder material and heat treated at 1100 °C in a pressureless nitrogen atmosphere. Si3N4 ceramics with controlled porosity of 34–47% were obtained. The distribution of porous structure was homogenous. Fully dense Si3N4 ceramics could be sintered at 1400∼1600 °C by using MgO and alumina Al2O3 as the sintering aids. Pore gradient structure was formed by laminating the Si3N4 porous ceramics and powder mixture was used to obtain fully dense ceramics, and then sintering at 1400–1600 °C. Microstructure of sintered samples was observed by scanning electronic microscope (SEM) and the change of phase compositions was analyzed by X‐ray diffraction (XRD). The results showed that these samples exhibited a good porous graded structure with a highly porous layer and a dense surface layer. The major phase of the Si3N4 ceramics was still α phase.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Pulsed laser deposition of stoichiometric KNbO 3 films on Si (100)

引用

Thin Solid Films 2008年第23期516卷 8559-8563页

作者： R. Yang S.Y. Shen C.B. Wang Q. Shen L.M. Zhang School of Materials Science and Chemical Engineering China University of Geosciences Wuhan 430074 PR China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 PR China

KNbO 3 films were prepared on Si (100) substrates by pulsed laser deposition. The effect of experimental parameters on the films structure and composition was investigated. Well crystallized and single-phase KNbO 3 films were obtained at the substrate temperature of 650 °C, laser energy of 7.5 mJ/pulse and target-substrate distance of 40 mm, but a severe potassium-deficient was observed in the deposited films. The mechanism of K deficiency in films was explored and a method to control the composition was designed. The experimental results indicate that the composition of films can be well controlled by adjusting the oblique angle of substrates from the axial direction of plume. The stoichiometric KNbO 3 films with K/Nb molar ratio of 0.98 were obtained by locating the substrate at an oblique angle of 3–12° from the plume axis.

关键词： KNbO 3 thin films Pulsed laser deposition (PLD) Composition control Potassium niobiate X-ray diffraction Electron probe microanalysis

来源：评论

学校读者我要写书评

暂无评论

Preparation of High Performance Grccn Alumina Ceramic Balls by Roller Production Waste

引用

Journal of Wuhan University of technology(materials Science) 2008年第1期23卷 134-138页

作者：钟莲云吴伯麟 ZHANG Lianmeng ZHANG Guifang State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Key Lab of Nonferrous Materials and New Processing Technology （ Guangxi University Guilin University of Technology ） of Ministry of Education Guilin 541004 China School of Chemistry and Ecological Engineering Guangxi University for Nationalities Nanning 530006 China

To reuse roller waste as a raw material of high performance green ceramic balls, three kinds of white alumina ceramic balls whose wear resistance were 2-3 times of the best high alumina ceramic ball with 90% Al2O3 were prepared, and the Al2O3 content of the prepared balls was 75%. It is found that the effect of calcia and magnesia on the wear resistance of ceramic balls is contrast to the accepted one： the wear rate of the ceramic balls prepared in CaO-Al2O3-SiO2 system is the lowest and the wear rate of the ceramic balls prepared in MgO-Al2O3-SiO2 is the highest. The main crystal phase of the ceramic ball is mullite and corundum. The ceramic ball granular is uniform and fine with 4-5 μm average size. The pore diameter is about 2 μm. The wear way of the ceramic balls is mainly transcrystalline fracture.

关键词： roller production waste alumina ceramic ball wear resistance white transcrystalline fracture

来源：评论

学校读者我要写书评

暂无评论

Generating Quasi‐Isentropic Loading to Targets via Flier‐Plate Technique

引用

AIP Conference Proceedings 2008年第1期973卷 850-855页

作者： Shen Qiang Su Xiaopeng Wang Chuanbin Zhang Lianmeng Hua Jinsong Tan Hua aState Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P.R. China bLaboratory for Shock Waves and Detonation Physics Research Chinese Academy of Engineering Physics Mianyang 621900 P.R. China

The quasi‐isentropic loading technique allows investigation of material properties in a high‐pressure, low‐temperature regime that is inaccessible by conventional shock wave experiments. In the present paper, the layered flier‐plate and graded density flier‐plate, which have different variations in the density gradient along the thickness direction but the same density range, were designed and fabricated. Impact experiments were then performed on a two‐stage light gas gun. VISAR‐measured results show that wave profiles with an initial jump followed by a slowly‐rising front to the peak velocity amplitude are generated by using both types of the flier‐plate, indicating that quasi‐isentropic loading to the targets have been successfully realized. The process of quasi‐isentropic loading can be seen as the successive overlap of a series of small shock waves by the transient layers in the flier‐plate. It is obvious that the graded density flier‐plate creates a more smoothly rising front, and the compression effect must be closer to isentropic loading than that of the layered flier‐plate with the same density range.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Effects of Phosphorus Additions on Microwave Sintering Properties of Uitrafine WC-10Co Cemented Carbides

引用

Journal of Wuhan University of technology(materials Science) 2007年第4期22卷 725-727页

作者：全峰周建 State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology State Key Lab of Advanced Technology for Materials Synthesis and Processing Wohan University of Technology

Using the microwave sintering technology, the effects of phosphorus （P） additions on the microstructure and properties of the ultrafine WC-10Co alloys were investigated. The experimental results show that with only 0.3wt% P additions, full density WC-10Co cermets were obtained at temperature of 1250℃, which is 70 ℃ lower than that of the undoped counterparts. Lower sintering temperature can result in finer WC grain growth; therefore, the P-doped WC-10Co alloys exhibited higher hardness than the undoped ones. But at the same time, P doping could lead to sacrifice of fracture toughness ofWC-10Co cemented carbides.

关键词： microwave sintering cemented carbides ultrafine hardmetals phosphorus grain growth inhibitor

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：