Mechanical and Electrical Technology IV

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Authors: Jie Yao, Young Hong Zhu, Yun Zhang Wu
Abstract: Based on thermodynamics and phase transformation driving force, we apply a SMA constitutive model to analyze the large and small deformation of SMA materials. Simulations under different loading, uniaxial tension and shear conditions, illustrate the characteristics of the model in large strain deformation and small strain deformation. The results indicate that the difference between the two methods is small under the uniaxial tension case, while the large deformation and the small deformation results are very different under shear deformation case. It lays a foundation for the further studies of the constitutive model of SMA, especially in the multiaxial non-proportional loading aspects.
Authors: Liang Yan Chen, Chao Fang
Abstract: ZnSe thin films were obtained through chemical bath deposition method. Structural and optical properties of as deposited and annealed samples were investigated by X-ray Diffraction and spectrophotometer. The as deposited thin films were in nanocrystalline, with lots of strain and a blue shift of optical band gap. After annealing, the crystal grain gained, the strain eased and optical band gap enlarged. And it suggested that annealing can ease the quantum effect of chemical bath deposited ZnSe thin films.
Authors: Shu Xia Lin, Wen Ke Bao, Jun Gao, Jia Bin Wang
Abstract: In the paper, the characteristic of intergranular corrosion on austenitic stainless steel is presented. The principles and the influencing factors of intergranular corrosion are analyzed in detail. Furthermore, the effective measures to prevent intergranular corrosion are proposed. Finally, the evaluation methods of sensitivity to intergranular corrosion are introduced.
Authors: Bao Dong Bai, Bo Zhang, De Zhi Chen, Wu Hao Jia, Bing Yin Qu
Abstract: The operation characteristic of transformer when DC bias phenomenon occurred was detected by Epstein frame. Results with different methods of joint forms are obtained in this paper. The circuit structure and measuring principle were analyzed in detail. Average magnetizing curve, magnetic hysteresis loop and loss curve with joint forms method of full tap and 30°,60° tap were obtained. The theoretical basis and experimental evidence for improving the capacity on restraining DC bias during designing transformer are provided.
Authors: Zhong Qiang Zhang, Guang Gui Cheng, Jian Ning Ding, Zhi Yong Ling
Abstract: Molecular dynamics simulations are carried out to explore the fluid flows in parallel-plate nanochannels. A “channel moving” pressure-driven model is utilized to study the planar Poiseuille flows. Considering the slip boundary conditions, relationships among the pressure gradient, mean flow velocity and the channel width are investigated to couple the atomistic regime to continuum. The results show that the mean flow velocity almost linearly increases with the increase of the pressure gradient. The slope of the linear relationship between the pressure gradient and the mean flow velocity is nonlinearly decreased with increasing the channel width. The results indicate that the approximate accuracy is reduced with decreasing the channel width while the pressure-driven flows confined in nanochannels are approximately described by the Navier-Stokes equations.
Authors: Lin Bo Li, Jing Guo, Fei Peng Lou
Abstract: In this paper, the corrosion behaviors of Sm-based bulk metallic glasses (BMGs) were investigated by immersion test. It was found that with Co content increasing the ability of corrosion resistance of the alloy increases for Sm-based bulk metallic glasses. A comparison study was made on the corrosion behaviors between the glassy state alloys and crystalline alloys with the same ingredients. The results show that the glassy state alloy has the better corrosion resistance.
Authors: Yan Gang Wang, Xing Hua Tong, Yong Jiang, Yong Liu, Lin Sen Zhu
Abstract: The corrosion characteristics of mild steel in real sea water are investigated by electrochemical test in this paper. Polarization curves and electrochemical impedance spectroscopy (EIS) are got by electrochemical workstation. From polarization curves, it is found that the corrosion rate rises at the initial period, and it becomes the highest on the 3rd day, then drops, and it tends to be stable after about 15 days, which is confirmed by EIS. In addition, the experiments also show that the corrosion layer can suppress the corrosion process. The electrochemical corrosiveness of the mild steel is analyzed in this study, and it lays a foundation for anticorrosion technology research.
Authors: You Qiang Xing, Jian Xin Deng, Ze Wu, Yun Song Lian
Abstract: Three different textures were produced by Laser Surface Texturing (LST) on Al2O3/TiC ceramic surfaces. MoS2 solid lubricants were filled into the textures. The friction and wear properties of textured and untextured surfaces were investigated by carrying out sliding tests against AISI440C stainless steel balls. Results showed that the textured surfaces filled with MoS2 solid lubricants exhibited lower friction coefficient and excellent anti-wear properties compared with untextured surfaces. At the texture spacing of 100μm, 150μm and 200μm, wavy textured surface had the lowest friction coefficient, while it was the dimpled surface at the texture spacing of 250μm. MoS2 film in the spaces between the textures was formed by mechanical engagement of particles in the rough surfaces and solid lubricants in textures. The friction coefficient and wear rates were reduced by supply of solid lubricants from the textures to the surfaces, bulges around the textures and TiO2 formed after laser texturing.
Authors: Yong Liu, Xing Hua Tong, Bao Guo Li, Yan Gang Wang, Lin Sen Zhu
Abstract: In order to study the corrosion behavior of Q235B steel in seawater at Weihai, the indoor simulated and accelerated corrosion test is carried out by adding H2O2 in seawater. Tafel polarization curves and electrochemical impedance spectroscopy (EIS) techniques are employed to investigate the corrosion electrochemical behavior of Q235B steel. Polarization curves and EIS are acquired by electrochemical workstation. From polarization curves, it is found that the corrosion rate rises rapidly during the initial period, and it becomes highest on the 3rd day, then drops, and tends to be stable after about 15 days. After that, the corrosion rate reduces slowly due to the covering effect of corrosion products, and then the conclusion is confirmed by EIS analysis. Analytical results indicate that the rust layer plays a positive role of hindering the corrosion process.

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