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Authors: Hiroshi Fukushima, Isamu Kuchiwaki, Takahiro Hirabayashi
Abstract: In situ high-resolution transmission electron microscopy experiments were applied to examine the nano-scale solidification process of boron-doped silicon from the liquid state. Fine particles of the specimen were first heated up to the melting temperature using a TEM heating-holder, and then gradually cooled across the melting temperature. The specimen was observed nearly along [001] direction. The lattice fringe of (220) plane was observed during solidification, and this part combined with the other liquid part to make a twist boundary. The angle between the (220) planes of these two crystal grains was close to the rotation angle of the (001) Σ5 twist boundary.
Authors: Xiaogang Shang, Christiane Mázur Lauricella, Sérgio Duarte Brandi
Abstract: The spreading of a liquid on a solid surface is very important in a number of practical applications. Many interesting physical phenomena can be observed when a small drop of a fluid spreads on a solid surface. These phenomena are related to spreading dynamics, which can be classified as spontaneous and forced wetting. In this work spreading dynamics of liquid metals and solders alloys were established to determine the mechanism of spreading. The spreading dynamics of bismuth, tin, 99.3wt%Sn-0.7wt%Cu alloy, 99.8 wt%Bi-0.2wt%Cu alloy and 60wt%Sn-40wt%Pb were studied by using sessile droplet method. Tests were carried out at a temperature range from 280oC to 350oC over a copper substrate. Results showed a discontinuous decrease of spreading velocity as a function of time. For example, spreading velocity of liquid tin at 320oC decreased from 234.86 mm/s at 0.0025 s to 4.62 mm/s at 0.0225 s, after that increased up to 9.24 mm/s at 0.025 s, then down back to 6.07 mm/s at 0.03 s, and finally reached to the end of spreading after 0.04 s.
Authors: Tadeusz Wierzchoń, Halina Garbacz, M. Ossowski
Abstract: The rapid progress in engineering enhances the demands set on materials requiring better mechanical properties, resistance to frictional wear, corrosion and erosion etc. These demands can be also satisfied by e.g. applying various surface engineering techniques which permit modifying the microstructure, phase and chemical composition of the surface layers produced on the treated parts. A prospective line of the development is the production of the intermetallic layers by combining various methods aimed to improve essentially the performance properties and service life of the treated parts. The paper presents properties of the Al2O3+TiAl3+TiAl+Ti3Al type layer produced on titanium alloy Ti6Al2Cr2Mo by duplex method combined with magnetron sputtering process of aluminium coating with a glow discharge assisted treatment. The results of the examinations: microstructure, chemical and phase composition, frictional wear resistance and mechanical properties are discussed. Produced composite surface layers have the diffusion character and a precisely specified structure, chemical and phase composition and good wear and corrosion resistance what can widen significantly application range of treated parts.
Authors: Jerzy Robert Sobiecki, R. Sitek, Tadeusz Wierzchoń
Abstract: The paper presents the use of trimethylaluminum in PACVD method to obtain the surface layers like alumina or aluminum nitride on Inconel nickel alloy. The glow discharge nitriding at a temperature of 750°C leads to the formation of aluminum oxynitride in the layer, whereas annealing in argon plasma at a temperature of 1050°C – to the formation of nickel and aluminum based intermetallic phases of the NiAl or Ni3Al type with aluminum oxide present within the outer zone of the coating. The presence of the surface layer of the Al2O3+NiAl+Ni3Al type formed on nickel alloys may be significant from the point of view of the applications that require a high heat resistance.
Authors: Si Young Choi, Suk Joong L. Kang
Abstract: The design of microstructure in materials, ranging from ultrafine, moderately sized, duplex to single crystalline, has long been a challenging subject to material scientists. A basic means to achieve this goal is related to the control of grain growth. Taking BaTiO3 as a model system, this investigation shows that control of grain boundary structure between rough and faceted and control of initial grain size can allow us to achieve the goal. When the grain boundary is rough, normal grain growth occurs with a moderate rate. On the other hand, for faceted boundaries, either abnormal grain growth or grain growth inhibition occurs resulting in a duplex grain structure or fine-grained structure, respectively. Growth of single crystals is also possible when the boundary is faceted. During crystal growth amorphous films can form and thicken at dry grain boundaries above the eutectic temperature. As the film thickness increases, the growth rate of the crystals is reduced. This observed growth behavior of grains with boundary structure is explained in terms of the difference in mobility between the two types of boundaries. The results demonstrate the basic principles of obtaining various microstructures from the same material.
Authors: Qing Ju Liu, Jin Zhang, Zhongqi Zhu, Yingxia Jin, Qing Hui Wang
Abstract: TiO2-Al2O3 composite thin films were fabricated on soda-lime glass with sol-gel technology. By measuring the contact angle of water with the film surface and the analysis of the XRD and XPS, we studied the influence of Al2O3 doping concentration and film thickness on the hydrophilicity of the composite films. The results indicate that the doping of Al2O3 into TiO2 and the relatively large thickness of the films can improve their hydrophilicity.
Authors: Na-na Jiang, Tian Min Shao, Da Rong Chen
Abstract: Diamond like carbon (DLC) films were prepared on Si wafer, using laser induced arc deposition (Laser arc) technique. Results of Raman Spectra analysis showed that the as-deposit films were amorphous, having obvious sp3 structure. Meanwhile, surface topography and micro-tribological properties were investigated by using Atomic Force Microscope and Nano-Scratch Tester. Influences of arc voltage, substrate bias voltage, target materials and substrate pre-treatment methods upon the film structures and film properties were studied.
Authors: Jian Gang Qian, Di Li, Feng Zhang
Authors: Yuan Zhou, Xiao Fang Bi, Jia Xiang Shang, Hui Bin Xu
Abstract: A series models of Ni3Fe/Al2O3/Ni3Fe magnetic tunnel junction with Al-terminated interfaces have been established for investigating the influence of ferromagnetic layer thickness on the electronic structure, employing first-principle methods based on local spin-density approximation theory. The spin polarization of the interfacial Ni3Fe monolayer shows a maximum value as the thickness of ferromagnetic layer increases. The Al monolayers at the ferromagnetic/insulating interface and the O monolayer in the interior of insulating layer are also studied in terms of the change of spin polarization with the ferromagnetic layer thickness. In addition, we have found that the structure of Ni3Fe monolayer has a great influence on the spin polarization.
Authors: I.K. Then, M. Mujahid, B. Zhang
Abstract: The present work deals specifically with the development of zirconium oxide thin film coatings on the stainless steel orthodontic bracket system by sputtering technique. Thin films of zirconium oxide have been deposited on injection molded stainless steel substrates using sputtering under controlled temperature and environment conditions. The deposited films, 1.5 µm in thickness, were found to have a predominantly tetragonal structure with grain size of about 5 nm. The grain size was found to increase only slightly with increasing heat treatment time at 650°C. It has been shown that thin-film zirconia coatings with stable structure and good adhesion along with very low friction coefficient could be produced.

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