Papers by Author: Yu Li Sun

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Authors: Duo Sheng Li, Dun Wen Zuo, Yu Li Sun, Rong Fa Chen, Wen Zhuang Lu, Bing Kun Xiang, Min Wang
Abstract: Diamond spherical shell thick film was prepared by high power DC-plasma jet CVD. Atom force microscopy, scanning electron microscopy, Raman spectroscopy and roughness-profile-meter were used to characterize microstructure, morphology, impurities and orientation evolution of diamond spherical shell thick film. The results show that, when nucleation begins, grains grow random orientation. The grain size of spherical diamond film prepared is compact, clear, uniform, continuous and no remarkable bigger grain over the whole surface of film. On the growth surface, (100) facets were dominant, and the cross-section SEM indicated that film columnar spreading grew from the substrate surface to the diamond film surface. The roughness of the growth surface was much more than that of the nucleation surface. To adjust some important parameters as methane concentrate, depositing time, and matrix temperature, and high quality diamond spherical shell thick film was deposited.
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Authors: Yu Li Sun, Dun Wen Zuo, Jun Li, Wen Zhuang Lu, Z.Z. Yu
Abstract: Ice fixed abrasives (IFA) polishing is a novel ultra-precision machining method. The motion tracks of abrasives during IFA polishing have an important effect on the quality of the machined silicon wafer. Firstly, the motion tracks of IFA polishing are theoretically analyzed in this paper. It is founded that the paths of any point in the IFA polishing pad relative to the wokpiece are a group of cycloids. Then, the motion tracks of single abrasive and multiple abrasives in the IFA polishing pad are simulated respectively. The results show that increasing the eccentricity is beneficial to the enlargement of the size range of polishing process. With the increasing of the speed ratio between the IFA polishing pad and the workpiece, the abrasive at higher speed can leave longer tracks on the workpiece than that at lower speed at the same time. The more the abrasives, the more uniform the mark density under the influence of more abrasives.
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Authors: Yu Li Sun, Dun Wen Zuo, Yong Wei Zhu, Ming Wang, H.Y. Wang, Li Gang Zhao
Abstract: The friction behavior of single silicon wafer sliding against different ice counterparts (α-Al2O3, CeO2 and SiO2) at 10±0.5 °C within a velocity of 60 rpm~300 rpm were studied using a home-made friction and wear testing machine. The morphologies and surfaces roughness of the worn silicon wafers were observed and examined on a non-contact surface topography instrument (ADE). It was found that the friction coefficient of the single silicon wafer decreased with the increase of sliding velocity. Single crystal silicon wafer coupled with α-Al2O3 ice counterpart recorded the highest friction coefficient and the biggest surface roughness, while it had the lowest friction coefficient and the smallest surface roughness as with CeO2 ice counterpart. One reason was that a series of tribochemical reactions occurred at the local contact point between the ice counterpart and the silicon wafer during sliding. Under alkaline condition, there would be a soft corrosion layer formed on the surface of the silicon wafer. Another reason was that the hardness of the abrasive particles was different and this caused different cutting depth of them.
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Authors: Li Gang Zhao, Dun Wen Zuo, Yu Li Sun, Min Wang
Abstract: The experimental research on silicon was reported in this paper. The surface roughness under the different workpiece feed speed and linear velocity of the wire saws is studied mainly in this experiment. The effects of the workpiece feed Vs and the linear velocity of the wire saws Vw were analyzed.
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Authors: Yu Li Sun, Dun Wen Zuo, Yong Wei Zhu, Rong Fa Chen, D.S. Li, M. Wang
Abstract: Cryogenic polishing single silicon wafer with nano-sized CeO2 abrasives can be known as cryogenic fixed abrasives CMP (CFA-CMP). The abrasive slurry was made of nano-sized CeO2 particles dispersed in de-ionized water with a surfactant and the polishing slurry froze to form cryogenic polishing pad. Then the polishing tests of the blanket silicon wafers in the presence of the cryogenic polishing pad containing the nano-particulates were carried out. The morphologies and surfaces roughness of the polished silicon wafers were observed and examined on an atomic force microscope (AFM). The results show that a super smooth surface with roughness of 0. 293 nm is obtained within 5000 nm× 5000 nm and the removal of material is dominated by plastic flowage.
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Authors: Yu Li Sun, Dun Wen Zuo, Wen Zhuang Lu, Yu Fei Zhao, Jing Kang, Min Wang
Abstract: The key question in the ice fixed abrasives (IFA) polishing is how to keep suitable ambient temperature in production process in order to avoid premature failure of the IFA. Based on above, the three dimensions finite element analysis (FEA) model of IFA polishing temperature field is built up at first. Then, the model reliability is demonstrated by experiments. Effects of ambient temperature and polishing time on temperature distribution and melting rate of the IFA pad are researched. The results show that the ambient temperature should be kept at about 10 °C in order to control the melting rate of the IFA pad effectively and keep longer polishing time. All the results provide the basis for choosing suitable ambient temperature in polishing.
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Authors: Shou Xin Yu, D.W. Zou, X.L. Zhu, Yu Li Sun, L. Zhou
Abstract: A friction and wear experiment was carried out at different areas of single crystal silicon under same surface roughness. Friction mechanisms at different area were analyzed by STM and 3D profiler. The result showed that the friction and wear properties were obviously different at different area although they had same surface roughness. The friction and wear properties of the single crystal silicon where closest to inner-cycle internal were best while the farther from the inner-cycle silicon area or closer to crystal silicon cylindrical, the worse friction and wear properties were. Abrasive wear and adhesive wear were the primary wear mechanisms.
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Authors: Duo Sheng Li, Dun Wen Zuo, Rong Fa Chen, Yu Li Sun, Bing Kun Xiang, Wen Zhuang Lu
Abstract: In this paper, a new polishing technique was proposed to polish concave spherical surface by diamond spherical shell deposited by DC-Plasma Jet CVD(chemical vapor deposition), and preparation was studied from both experiment and theory. The deposited films were investigated by some techniques including: scanning electron microscopy (SEM), atom force microscopy (AFM), Raman spectroscopy, and roughness-profile-meter, which were used to analyze surface phase, microstructure, internal quality and surface roughness. The results show that the deposited diamond spherical shell film has some remarkable properties, such as high surface density, high hardness. Compared to traditional polishing techniques, it will have some potential advantages as convenient, flexible, efficient and precious. To adjust some important parameters as methane concentration, depositing time, and it can deposit the different size grain diamond spherical shell films, which are used to polish different precision degree concave spherical surfaces. Meantime, to change curvature of diamond spherical shell, it can adapt to polish various curvature radius concave spherical surfaces.
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Authors: Rong Fa Chen, Dun Wen Zuo, Yu Li Sun, Duo Sheng Li, Wen Zhuang Lu, Min Wang
Abstract: Strain films in the thin film resistance strain gauge are prepared by magnetron sputtering method. Some results concerning the electromechanical and structural properties of nichrome (Ni80Cr20 wt.%) thin films are presented. As compared to the well-known Ni-Cu (constantan) alloy film, which are widely used for manufacturing pressure and force sensors, nichrome (Ni80Cr20 wt.%) thin films exhibit gauge factor values of the same order of magnitude, but they are much more corrosion resistant and adherent to the substrate. The influences of composition and post-deposition annealing on the electrical resistance, temperature coefficient of resistance (TCR) and gauge factor of nichrome (Ni80Cr20 wt.%) thin films are discussed.
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Authors: Rong Fa Chen, Dun Wen Zuo, Yu Li Sun, Wen Zhuang Lu, D.S. Li, M. Wang
Abstract: Although research on various diamond polishing techniques has been carried for years, some issues still need to be examined in order to facilitate application on large areas in a cost-efficient manner. A compositive technique for machining efficiently thick diamond films prepared by DC plasma arc jet is reported in the present paper. A two-stage polishing was applied on thick polycrystalline diamond films, by employing first electro-discharge machining (EDM) for rough polishing and subsequently mechanical polishing for finishing operations. Experimental results obtained clearly indicate the applicability of the proposed two-stage technique for fabricating transparent diamond films that can be used for the production of X-ray windows. Appropriate etching with EDM is an effective pretreatment method for enhancing the efficiency of rough polishing process in mechanical polishing of thick diamond film. The machined surfaces of diamond films are studied by Scanning Electron Microscope (SEM) and Raman Scattering Spectroscopy (Raman).
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