Papers by Keyword: Surface Topography

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Authors: Ming Jun Chen, Qi Long Pang, Jing He Wang, Kai Cheng
Abstract: 3Dfractal dimension and 2D profile fractal dimension distribution of the surfaces made by brittle or ductile grinding are calculated. From the calculated results of 3D fractal dimension, it can be found that the microtopograhpy of ductile ground surface is more exquisite than brittle ground surface and 3D fractal dimension Ds has inverse relation with the roughness parameter Rq. Through the analysis of 2D profile fractal dimension distribution in different ground surfaces, it is revealed that the topography of ground surface is changed with grinding parameters such as ground surfaces may have weakly or strongly anisotropic even isotropic features when different grinding parameters are adopted. Using fractal method to analyze the topography of ground surface is helpful to understand the generating mechanism of surface topography.
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Authors: Guna Civcisa, Tõnu Leemet
Abstract: This paper presents a study of 3D surface texture measurements and analysis of several surface texture parameters. A stylus measuring instrument was used to measure 3D surface topographies. In experimental part of this study, two coated gas turbine blades used in aerospace industry were chosen to examine surface of the coatings in nano-scale. Surface texture parameters of Ti-Al coating and Ti-Al-N coating were measured and compared to each other. The aim of the research is to analyze the surface of these coatings in an areal (3D) manner. The results indicate slight differences between these two surface textures despite the fact that both are Titanium-based coatings, and the surface of base material for both samples was prepared in the same way before deposition. Further study with repeated measurements of surface texture for deposed coatings has to be made after erosion tests.
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Authors: Yan Qing Tan, Lian Hong Zhang, Ya Hui Hu
Abstract: Dynamic contact model of rough surfaces can provide the theoretical basis for analyzing the microscopic damage of surfaces in wear process and constructing the analytical wear model to predict wear. A dynamic contact model of sliding rough surfaces is innovatively constructed based on the characterization of the contact asperities on rough surfaces in this paper. Firstly, an asperity model of rough surface is set up according to the surface topography parameters and the static contact parameters is evaluated in the light of statistics contact theory; Then the contact characteristic of surface topography in sliding is analyzed and a series of equivalent contact models are proposed; Finally, the dynamic contact model of rough surfaces is established and from which the dynamic contact parameter of rough surfaces is formulated. The dynamic contact model can be further improved to analyze the friction fatigue wear of sliding pairs and provide reference for tribology design of mechanical surfaces.
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Authors: Georg Peter Ostermeyer
Abstract: The analysis of friction in brake systems shows a complex dynamic dependence of friction and wear. Friction produces wear but wear affects the surface topography and by that the friction power itself. The wear in technical brake systems causes a dynamic equilibrium of growth and destruction of surface structures on the brake pad, carrying the friction power. This interaction between friction and wear generates a new dynamic friction law, which describes the effects on friction, wear and temperature on different time scales. For very slow processes the friction law reduces to the classical form, describing only the velocity and heat dependence of friction. For unsteady processes the dynamic friction law is able to describe and explain even complex measured friction events in brake systems.
105
Authors: Zhao Zhong Zhou, Ju Long Yuan
Abstract: In order to kinematic simulate the lapping process with the semi-fixed abrasive plate; a fractal modeling of the semi-fixed abrasive lapping abrasive plate’s surface topography is presented in this paper. A numerical procedure for effectively generating the semi-fixed abrasive lapping abrasive plate surface topography is suggested. The procedure is based on the fractal characteristic of the semi-fixed abrasive plate and the fractal dimension was obtained from the measured structure function of the abrasive plate surface used the Digital Microscope Resources Center. Numerical examples are used to illustrate the viability of the approach. It would be powerful to describe the complex interaction of the abrasive plate and workpiece.
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Authors: Feng Wei Huo, Zhu Ji Jin, Ren Ke Kang, Dong Ming Guo
Abstract: A new non-destructive method was developed to identify the grinding mode of silicon wafers, which is based on the information of subsurface cracks extracted from the surface topography of the ground silicon wafers measured with a 3D surface profiler. We examined extensive measurement data of the surface topography of silicon wafers processed by single grain grinding or real grinding operation, and our results show that the information about median cracks could be captured if the lateral sampling interval of the 3D surface profiler is small enough, even if the grain depth of cut is below 20nm. If the maximum valley of the measured surface topography is approximately equal to the grain depth of cut, surface formation will be under ductile mode, whereas, if the maximum valley is several times larger than the grain depth of cut, surface formation will be under brittle mode. According to this criterion, silicon wafers ground by ductile mode or brittle mode could be identified rapidly and conveniently. Experimental validation shows that this method is accurate.
255
Authors: Dinesh Setti, Benjamin Kirsch, Jan Christian Aurich
Abstract: Visualization of work surface topography through simulations is very challenging task in grinding process due to the complexity of wheel-work interactions with a very high number of cutting points (grits). Kinematic mapping of abrasive grits on a three-dimensional wheel topography enables the evaluation of ground surface topography through simulations. In this paper, a method for generating the ground surface topography based on wheel specifications is presented. Abrasive grits size, abrasives volume percentage and their nature of distribution on the wheel surface are considered in the modeling and visualization of wheel topography. The simulation results of ground surface topographies prove the feasibility of the developed method.
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Authors: Marta Harničárová, Jan Valíček, Jana Müllerová, Milena Kušnerová, Radovan Grznárik, Pavel Koštial
Abstract: Laser - cut quality is mainly characterized by a degree of accuracy in shape, size and also by surface layer conditions after cutting associated with surface roughness. An experimental determination of surface tension (or tensor components) of clean metal surfaces is very difficult and there is no direct method for its measurement. Attention was paid to numerical derivation of surface tensions according to the surface topographical features in laser cutting technology. The surface tensions and temperature dependencies of several metallic materials have been determined and confirmed by data obtained from the literature. It was found to be in very good agreement between our results and data from different sources in the literature.
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Authors: Peng Zhang, Bo Wang, Mark J. Jackson, Xing Mao
Abstract: Current requirements for producing highly precise and ultra-smooth micro structured surfaces of small parts are proposed in certain situations. The following question arises: how to make a highly precise and ultra-smooth micro-structured surface with high efficiency and low cost? Novel desktop lapping and polishing devices should be developed to satisfy these requirements. In order to improve the surface topography and remove the surface damaged layer of a highly precise and ultra-smooth micro thin-walled structure after milling with the width of 150 μm and the depth of 10 μm, a novel lapping desktop device is designed and developed. There are two key points in the design of the lapping desktop device: one is the vertical coupled macro-micro movement axis; the other is the fixture with a thin and flexible hinge structure, which has the capability of measuring both force and displacement as a double-feedback sensor to control both the micro lapping force and the depth of lapping. The experimental results show that the surface topography of the micro thin-walled structured surface is much improved after lapping, and that the three-dimensional surface roughness decreased from 329 nm to 82.2 nm.
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Authors: S. Shanmugan, D. Mutharasu, Z. Hassan, H. Abu. Hassan
Abstract: Al thin films were prepared over different substrates at various process conditions using DC sputtering. The surface topography of all prepared films was examined using AFM technique. Very smooth, uniform and dense surface were observed for Al films coated over Glass substrates. The observed particle size was nano scale (20 -70 nm) for Glass substrates. Sputtering power showed immense effect on surface roughness with respective to Ar gas flow rate. Noticeable change on surface with large particles was observed in Copper substrates at various sputtering power and gas flow rate.
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