Advanced Engineering Materials II

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Authors: Chao Sun, Rujuan Shen, Min Song, Yong Du
Abstract: The effects of SiC particle size, volume fraction and tensile strain on the deformation behaviors of SiC particle reinforced Al matrix composites were studied by finite element method using microstructure based model. The results showed that the addition of reinforcements will result in no-uniform stress distribution in matrix. The maximum stress in the particles increases, and the minimum stress in the matrix decreases when the SiC particle volume fraction increases, indicating more load being transferred from matrix to particles with increasing the SiC particle volume fraction. It also showed that as the tensile strain and SiC particle size increase, the maximum stress in the particles increases. It can thus be concluded that small-sized SiC particles can endure more loads and improve the mechanical properties of the composites.
Authors: Shao Fan Xu, Shao Ping Xu, Cheng Nan Zhu, Chuan Yong Yuan
Abstract: Copper-plated TiB2-Cu-graphite composite, Cf-TiB2-Cu-graphite composite and Cf-copper-plated TiB2-Cu-graphite composite with the same TiB2 content were prepared by the powder metallurgy method. Physical and mechanical properties of these composites were tested. The dry friction tests of the composites under sliding velocity of 10m/s and load of 4.9N were conducted for 36h. The results show that the properties of the Cf-copper-plated TiB2-Cu-graphite composite such as electric conductivity, hardness, bending strength and wear resistance are increased remarkably than those of either Cf-TiB2-Cu-graphite or copper-plated TiB2-Cu-graphite composites.
Authors: Long Hua Zhong, Yu Tao Zhao, Song Li Zhang, Rong Wen
Abstract: In situ TiB2/6061 composites have been successfully synthesized through chemical reaction between 6061 master alloy, Al-3B master alloy and Ti powder. The composites fabricated by direct melt mixing method was investigated by Scanning Electron Microscope (SEM), Energy Dispersive x-ray Spectroscopy (EDS) and X-Ray Diffraction (XRD), The results shown the existence of TiB2 particles. The size of most TiB2 particles were just in micron level, and even reached to sub-micron level. The increase in microhardness and tensile strength for the as-prepared composites with 5% particulate volume fraction (PVF) are up to 26.8% and 51.2% respectively.
Authors: Li Jun Zhang, Jing Pei Xie, Ai Qin Wang
Abstract: Al-50Si can be fabricated with a method in which air-atomization is followed by vacuum canning hot-pressing process. In order to improve the mechanical character and the physical property,the treatment of high-energy milling are used in the pretreatment of the powder of Al-50Si.The microstructure,density ,coefficient of thermal expansion are analyzed by scanning electron microscope(SEM) and thermal physical tester. It was found that the silicon grain was refined, the density and strength was improved when high silicon alloy powders were treated by high-energy ball milling.
Authors: Zdeněk Majer
Abstract: In this contribution the mechanical behavior of polymer particulate composite is studied. A numerical model is created as three phase continuum when a matrix, particles and an interphase are considered. Size of particles and properties of matrix are determined from experiment. A non-linear behavior of matrix is considered in calculations. The main objective is to estimate mechanical response of particulate composite depending on the change in matrix and interphase properties. The results are evaluated for different volume filler fraction of particles. The finite element commercial code ANSYS is used for calculations. Results indicated that by the change of volume filler fraction and properties of matrix and interphase it can be obtained composite with relatively different properties.
Authors: Xiao Fei Ding, Ai Guang Lin, Zhong Dong Xie, You Ming Diao, Chen Xiao Mu
Abstract: The ethoxy resin-based composite was made by imitating the structure of shell in the paper, and its structure and mechanical properties were studied . The results showed that the mechanical properties of the ethoxy resin-based composite with bamboo fibre and hemp fibre are higher than that of the ethoxy resin-based composite, and higher the toughness. The toughening mechanisms of the bamboo fibre and hemp fibre reinforced ethoxy resin-based composite have crack stagnation, microcrack, interface stripping, fiber extraction an
Authors: Tao Liu, Rong Bin Du, Xue Jun Kong
Abstract: Composite oxides materials CuSnO3 as anode materials for lithium-ion batteries were synthesized by chemical coprecipitation method using SnCl4•5H2O, NH3•H2O and Cu(NO3)2•3H2O as raw materials.The precursor CuSn(OH)6 and CuSnO3 powders were characterized by thermogravimertric(TG) analysis and differential thermal analysis(DTA), X-ray diffraction(XRD), and transmission electron microscope (TEM). The electrochemical properties of CuSnO3 powders as anode materials of lithium ion batteries were investigated comparatively by galvanostatic charge-discharge experiments. The results show the average particle size of amorphous CuSnO3 is 70nm. The initial capacity during the first lithium insertion is 1078 mA•h/g and the reversible charge capacity in first cycle is 775 mA•h/g. After 20 cycles, the charge capacity is 640 mA•h/g and this material shows moderate capacity fading with cycling. As a novel anode material for lithium ion batteries, amorphous CuSnO3 demonstrates a large capacity and a low insertion potential with respect to Li metal.
Authors: Hao He, Wei Li, Huai Zhong Xing, Er Jun Liang
Abstract: The electronic band structures, partial and total spin density of states of Cr, Fe, Mn and Ni doped β-Ga2O3 are studied. It is shown that there exists only one spin polarized state around the Fermi level for all doped β-Ga2O3. Ferromagnetism is predicted for Mn and Ni doped while spin-glass ground states are predicted for Cr and Fe doped β-Ga2O3. All doped β-Ga2O3 exhibits intermediate bands which are filled with only one spin state electrons and isolated from valence and conduction bands due to the splitting of the 3d orbitals by the potential of crystal and spin interaction
Authors: Xiang Yang Guo, Chun Zhen Fan, Xian Sheng Liu, Wen Bo Song, Chun Xiao Cheng, Er Jun Liang, Ming Ju Chao, Bin Yuan
Abstract: ZrO2-ZrW2O8 diphasic composites with controllable coefficients of thermal expansion (CTEs) are synthesized by rapid in-situ reactive sintering with ZrO2 and WO3 as reactants. High density of ZrO2-ZrW2O8 composites without decomposition of ZrW2O8 is obtained with Y2O3 sintering additive. The CTEs of specimen with ZrO2 to ZrW2O8 mass ratio 1:1.0, 1:1.3, 1:1.5 and 1:2.0 are measured to be about 1.20×10−6, 0.31×10−6, -0.78×10−6 and -1.13×10−6 K−1, respectively. Raman mappings demonstrate homogenous dispersions of ZrO2 and ZrW2O8 in the ZrO2-ZrW2O8 composites. In addition to the role as sintering additive, some Y3+ cations enter the lattice to substitute Zr4+ in ZrW2O8, leading to an increase in disorder and a decrease in phase transition temperature of ZrW2O8 in the composites.

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