Papers by Keyword: Micro-Topography

Abstract: The surface roughness morphology of cold rolled sheet treated with three coarsen processes, including shot blasting texturing, electro-discharge texturing and laser texturing, was examined and analyzed before and after stamping. The influence of the micro-topography on the plastic deformation behavior during forming was then discussed. The results revealed that the sheet with uniform dispersion micro-pit, large concave valley and smooth convex hull exhibits a good forming performance.

Abstract: This paper is based on the experimental observation. The micro-topography characteristics of electrical discharge machining (EDM) surface were studied. The results show that the EDM surface is made up of three-dimensional craters and hard protrusions overlapped alternately which distribute randomly and non-directionally. The pulse energy has significant effect on the forming of EDM surface profiles, and peak current and pulse width are the main factors.

Abstract: In processing of electrochemical finishing (ECF), electrochemical dissolution makes anodic surface micro-topography change. To identify the influence of the change on the distribution of electric-current field between electrodes, mathematical model describing the distribution of the electric-current field along the profile of the anodic surface micro-topography was established. The results of simulations and experiments show that the variation in the anodic surface micro-topography makes the distribution density of the electric-current uniform, and the sharp or peak-like micro-topography is in favour of improving the finishing ability of ECF.

Abstract: For the purpose of investigating the surface defects on the machined surface in high speed milling of SiCp/Al Composites, the high speed milling experiments were performed on the precision milling machine (ops650).The machined surface was observed and measured by the OLS3000 Confocal Laser Scanning Microscope. The surface defects on the machined surface were classified and investigated. The surface defects mainly include grooves and holes due to the pulled-out particle. According to the geometrical characteristics of the pulled-out particles.

Abstract: In order to gain a deep understanding of energy absorption property and failure mechanism of closed-cell foam metals, the dynamic energy absorption property of closed-cell foam metals with matrix Al, matrix Al-Si6, matrix Al-Si12 CCAF, Mg matrix, aluminum-fiber and RE-Al alloys are discussed based on the compression and energy absorption test. The influence of different basis materials on absorption property of closed-cell foam metals is discussed, too. It also shows the micro topography of CCAF during the compression process. In addition, micro-mechanics failure mechanism of CCAF is discussed. Results obtained in this research include: (1) the compression deformation curves of different foam metals indicate that matrix Al CCAF is better for energy absorption materials, because of the best energy absorption property and the high strength. (2) the strength of metal foams with matrix Al-Si6, matrix Al-Si12 and matrix Mg are higher than that of matrix Al CCAF, and also have better energy absorption property. However, the failure characteristics of brittle fracture indicate obvious in matrix Al-Si6, matrix Al-Si12 and matrix Mg. (3) the micro-topography of CCAF with matrix Al is simple and uniform. Also the fracture has obvious tear trace. Aluminum-fiber and RE-Al alloys have better compression property, but lower strength and no strength increasing stage lead to destroy suddenly. (4) the curves of energy absorption for matrix Al and matrix Al-Si6CCAF are on the rise. And the maximum of energy absorption is about 2.1MJ/m³. (5) micropore and crack of closed-cell foam metals provide a good space for the compression and energy absorption. Meanwhile, it is the main failure parts of damage. Keywords: closed-cell foam metal; dynamic energy absorption; micro-topography; micro-mechanics

Abstract: For the purpose of accurate inspecting IC chip by image, fuzzy gray theory is used for quantitative evaluating the IC micro-topography’s influence on its image characteristics. Through extracting topography’s feature-points by precise coordinate measuring apparatus, its spatial surface model is structured and the topography characteristic parameters array is established, thus a mathematical model of fuzzy gray evaluating system is obtained. After calculating the fuzzy gray relational degree between the topography characteristics and the image ones, the influence has been quantified. By experiment repeatedly the influence discipline is analyzed and the conclusions are reached. It provides theoretical foundation and technical preparation for IC image sampling condition’s selection and adjustment.

Abstract: For making accurate assessment about each characteristics paramete of three-dimensional surface micro-topography, mathematic model for the datum plane of three-dimensional surface micro-topography assessment was established with least squares method, the relational expression of the average fitting error and maximum error were made. The datum plane equation was found by processing experimental data with least squares fitting method. The rationality and feasibility of the algorithm which is used to establish datum plane were verified through error calculation and analysis of the datum plane equation. The research provides the foundation for parametric assessment of 3D surface micro-topography and provides a method for datum surface establishment of curved surface.

Abstract: In this paper, the micro-topography of the milled surface and chips are investigated, and the milling mechanisms of ceramics are analyzed. The results show that there are many deep and flat craters due to material fractures on the milled surface of Al2O3 ceramics and evidence of plastic flow is also observed around the craters. The milled surface of Si3N4 ceramics is smooth and even, and the trace of plastic flow can be observed. The abrasives after milling are very different from those before milling, which reflects the strong impact between abrasives and materials during the milling process. It is shown that the dominant milling mechanisms of ceramics are crack and exfoliating due to brittle fracture and plastic distortion according to the form of the chips.