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2011 IEEE International Symposium on Applications of Ferroelectrics(ISAF/PFM 2011) and 2011 International Symposium on Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar materials

作者： Minghe Cao Fan Li Mengpu Lv Hua Hao ZhiYong Yu Zhonghua Yao Hanxing Liu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WHUT Wuhan 430070 Hubei PR China School of Materials Science and Engineering WuHan University of Technology Wuhan 430070 Hubei PR China

ISBN: (纸本)9781457711626

Lead free textured K_(0.5)Na_(0.5)NbO_(3) piezoelectric ceramics have been prepared by reactive-templated grain growth method by using NaNbO_(3) with different morphologies as templates. The NaNbO_(3) template particles with different edge length (10-20 (mu)m) and thickness (0.5-2.5 (mu)m) was synthesized through controlling Bi_(1.5)Na_(x-1.5)Nb_(x)O_(3x+3) precursor's layer numbers x from 2 to 6 by two-step molten salt methods. The crystalline phases and microstructure of textured K_(0.5)Na_(0.5)NbO_(3) were characterized by X-ray diffraction and scanning electron microscopy, respectively. It shows that all the K_(0.5)Na_(0.5)NbO_(3) ceramics are orthorhombic perovskite structure with {001} orientation. By using the template particles with a ratio of edge length to thickness (l/h)(velence)approx10, the textured ceramics with optimized piezoelectric properties was prepared. The results indicate that the enhanced properties of textured ceramics are concerned with the template morphology.

关键词： K_(0.5)Na_(0.5)NbO_(3) ceramics Template morphology RTGG Textured ceramics

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Wear and corrosion properties of laser cladded Cu_(47)Ti_(34)Zr_(11)Ni_8/SiC amorphous composite coatings on AZ91D magnesium alloy

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1351-1355页

作者：黄开金闫里王存山谢长生周昌荣 State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and Technology State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology State Key Laboratory of Materials Modification by Laser Ion and Electron BeamsDalian University of Technology Guangxi Key Laboratory of Information Materials Guilin University of Electronic Technology

To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and *** wear and corrosion behaviours of the coatings were *** wear resistance of the coatings was evaluated under dry sliding wear condition at room *** corrosion resistance of the coatings was tested in 3.5%(mass fraction) NaCl *** coatings exhibit excellent wear resistance due to the recombined action of amorphous phase and different intermetallic *** main wear mechanisms of the coatings and the AZ91D sample are *** former is abrasive wear and the latter is adhesive *** coatings compared with AZ91D magnesium alloy also exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.

关键词： magnesium alloy AZ91D alloy laser cladding wear corrosion amorphous phase

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Effects of gas diffusion layer characteristic on the water-protect performance of low-humidity PEMFC

Effects of gas diffusion layer characteristic on the water-p...

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International Conference on Electric Information and Control Engineering (ICEICE)

作者： Wang Fangfang Luo Maji Zhang Xin Luo Zhiping Zhan Zhigang Wuhan University of Technology Wuhan Hubei CN State Key Laboratory of Advanced Technology for Materials Synthesis and Progressing Wuhan University of Technology China

ISBN: (纸本)9781424480364

The gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC) plays a prominent effect on the water balance inside the fuel cell. A two-dimensional, steady-state, two-phase model for a PEMFC is developed to investigate the effects of GDL characteristics on the water-protect performance of the fuel cell. Analysis of the water-protect performance of low humidity PEMFC indicates that in the condition of saturated anode inlet humidification and 25% of the cathode inlet humidification, the smaller the porosity, the better the water-protect performance of the fuel cell. The thicker the GDL, the better the water protect capability. The fuel cell with smaller mean aperture has higher water content in the membrane. The stronger hydrophilicity in the GDL plays a certain role of holding the water.

关键词： Fuel cells Protons Humidity Fuels Automotive engineering materials Water resources

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Mechanical property of boron carbide ceramics prepared by Spark Plasma reactive Sintering

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作者： Zhang, S. Wang, C.B. Chen, G. Shen, Q. Zhang, L.M. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

ISBN: (纸本)9780470927151

A novel way was used to prepare dense B4C ceramics at a lower temperature by reactive sintering from carbon and boron elemental powders. Spark Plasma Sintering (SPS) technique, a rapid and non-conventional powder consolidation method, was employed. The densification, microstructure and mechanical property of the as-prepared B4C ceramics were investigated. The reactive sintering process could be divided into two stages, corresponding to synthesis (1300∼1700°C) and densification (1700∼1900°C), respectively. At those stages, boron first reacted with carbon to form B4C, and then the in-situ densification of the as-synthesized B4C occurred and was enhanced by increasing sintering temperature. B4C ceramics with grain size of several hundred nanometers and high densification (98%) were obtained at 1800°C, a lower sintering temperature as compared with general hot press. Due to the high densification and purity as well as fine texture, the SPS-sintered B4C ceramics had high Vickers hardness (48.8GPa), Young's modulus (264.5GPa), fracture toughness (3.9MPa·m1/2) and flexure strength (450MPa).

关键词： Densification

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Investigation on Cracked Solder Ball of BGA Component

Investigation on Cracked Solder Ball of BGA Component

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2011 12th International Conference on Electronic Packaging technology & High Density Packaging(2011 电子封装技术与高密度封装国际会议)

作者： D.G Yang M.Cai B.Y Wu X.X Su F.Zhou D.J Xie Y.Tao Guangxi Key Laboratory of Manufacturing System and Advanced Manufacturing Technology Guilin Universi Flextronics Manufacturing Company Xin Qing Science and Technology Industrial Park Zhuhai P.R.Chin NVIDIA Corporation 2701 San Tomas Expressway Santa Clara CA USA State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Scie

One interesting and challenging BGA solder ball cracked issue occurred at certain electronic production line. This paper is expected to carry out a detail investigation and improvement plan on failure mechanism, by combining some experiment methods, such as SEM/EDX, pin pull test, cross section, dye & pry etc. And also environment test thermal cycling is involved in to qualify the improved products. Thermal stress, mechanical stress and strength of BGA solder ball will be studied as critical factors. The result revealed the crack tracing is along with IMC layer smoothly, and the IMC layer with poor mechanical strength is damaged easily during undergoing process mechanical stress, even through process strain level is within design specification. Meanwhile, the poor strength is shown by pin pull test on BGA solder balls, which means the solder ball strength can be tested by the pin pull test that is designed primarily for PCB pad to laminate strength. To solve the crack phenomenon on current PCBA without changing any BGA produced process, underfill and edge bonding process are suggested to protect the solder balls from mechanical and thermal stress shock. Reliability qualification plan is also conducted and confirmed that both processes solved the failure mechanism successfully. It is believed the history of the investigation and improvement on mentioned solder crack issue will be meaningful for electronic product manufacturing, especially for similar solder ball failure mode.

关键词： Stress Thermal stresses Strain Failure analysis Reliability Production Electronics packaging

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A facile route to prepare tetragonal BaTiO3 nanoparticle through composition control

A facile route to prepare tetragonal BaTiO3 nanoparticle thr...

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12th International Meeting on Ferroelectricity, IMF-12 and the 18th IEEE International Symposium on Applications of Ferroelectrics, ISAF-18

作者： Zhao, Guanghui Cheng, Xiangbang Liu, Hanxing State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

In the present work, tetragonal BaTiO3 particles down to 20 nm have been synthesized by low temperature aqueous co-precipitation method through composition control. Field emission scanning electron microscopy (FE-SEM) images indicated that the precipitates contained fine (about 20-30 nm) faceted particles. The Raman spectra revealed that tetragonal phase appeared with the increase in Ba/Ti ratio in the precursor solution. The appearance of tetragonal phase in BaTiO3 nanoparticle was related with the lattice defect revealed by lattice parameter and lattice strain calculated by XRD results. The lattice defect can be modified through composition control.

关键词： Raman scattering

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Corrosion Behavior of SnO2-based Electrode Ceramics in Soda-lime Glass Liquid

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IOP Conference Series: materials Science and Engineering 2011年第20期18卷

作者： Guoqiang Luo Qiang Shen Qizhong Li Dongming Zhang Chuanbin Wang Lianmeng Zhang State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Dense SnO2-based electrode ceramics have extensive application prospect in glass electric-melting industry due to the excellent electrically-conductive and chemical property in high temperatures and oxidation environment. In this paper, dense SnO2-based electrode ceramics doped with MnO2 and Sb2O3 were prepared by pressureless sintering method and the corrosion rate in soda-lime glass liquid as well as the microstructure evolution was mainly investigated. The results suggested that SnO2-based ceramics had good corrosion resistance, and the minimum value was only 2.54×10−4 mm/h when MnO2 content is 1.0% and Sb2O3 content is 0.1%. Composition Elements of Glass liquid were detected in the grain boundary and some intergranular pores. It was found that SnO2 grains remained unchanged, whereas MnO2 was easily dissolved into molten glass liquid. SnO2-based electrode ceramics with dense structure and few amounts of additives had excellent corrosion resistance to the molten glass.

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The effect of ZnO-B2O3-SiO2 additive on sintering and dielectric properties of Ba0.3Sr0.7TiO 3 ceramics

The effect of ZnO-B2O3-SiO2 additive on sintering and dielec...

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12th International Meeting on Ferroelectricity, IMF-12 and the 18th IEEE International Symposium on Applications of Ferroelectrics, ISAF-18

作者： Li, Y.Q. Liu, H.X. Yao, Z.H. Xu, J. Cui, Y.J. Cao, M.H. Hao, H. Yu, Z.Y. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 Hubei China

ZnO-B2O3-SiO2 additive with 0.55: 0.35: 0.10 molar ratio was added to Ba0.3Sr0.7TiO3 ceramics in order to lower the sintering temperature. The densification behavior, crystalline structure, microstructure, dielectric properties and breakdown strength of ceramics were studied. When 9 wt.% additive was mixed with pure Ba0.3Sr0.7TiO3 powder, the densification temperature of samples decreased from 1350°C to 1100°C compared with no additive system, and the sintered ceramics revealed dielectric properties at room temperature as follows: dielectric constant Εr = 413, dielectric loss tanδ = 0.00231 under 1 kHz and the breakdown strength Eb = 9.2 kV/mm.

关键词： Microstructure

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High temperature oxidation and oxide-film chemical removal technology of stainless steel cone-shape pipe in dieless drawing

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Cailiao Rechuli Xuebao/Transactions of materials and Heat Treatment 2011年第3期32卷 127-133页

作者： Mao, Hao-En Liu, Xue-Feng Peng, Bin Qin, Fang Xie, Jian-Xin State Key Laboratory for Advanced Metal and Materials University of Science and Technology Beijing Beijing 100083 China Key Laboratory of Advanced Processing Technology of Materials of Ministry of Education University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Hebei University of Science and Technology Shijiazhuang 050018 China

In dieless drawing process of 304 stainless steel cone-shape pipe, the thickness of oxide film and factors influencing the formation of oxide film were analyzed, and the effects of pickling temperature and pickling speed on the chemical removal process of the oxide film were studied. The results show that the oxide film thickness is gradually increased with the increase of deformation degree, the cone-shape pipe length, the induction heating temperature and the distance between hot and cold sources, and decreasing the feed speed. When the temperature of pickling solution (98%H2SO4(80~100 mL·L-1), NaNO3(40~50 g·L-1), NaCl(10~20 g·L-1), (CH2)6N4(3~5 g·L-1)) is 70~80°C, in order to remove the oxide film completely without excessive corrosion the cone-shape pipe is pulled out from the pickling sink at variable drawing speed, and the good surface quality of the cone-shape pipe is obtained.

关键词： Oxide films

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Effects of TiO2 Doping Fe-Mn-Cu-Co Spinel on the Physical Properties of Diesel Oil

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IOP Conference Series: materials Science and Engineering 2011年第20期18卷

作者： Dong Huang Jing Zhou Hongying Cao Ying Dai Wen Chen State Key Laboratory of Advanced Technology for Materials Synthesis and Processing School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 People's Republic of China

In this paper, Fe-Mn-Cu-Co spinel materials with high infrared radiation property were prepared by doping TiO2. The microstructure and infrared radiation with different doping contents of TiO2 were studied. The results show that infrared radiation of spinel materials were increased by doping TiO2 and the infrared absorption intensities of diesel oil in the ranges of 3000-2800 and 1500-1300 cm−1 were increased after activated by spinel materials. Diesel surface tension and viscosity were reduced after adding the spinels. When the doping amount of TiO2 was 10%, the effects on the decrease of the surface tension and viscosity reached the maximum.

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