Download or read book A Numerical and Experimental Study of Pulsed Laser Polishing of Metals at the Meso micro Scale written by Tyler L. Perry and published by . This book was released on 2009 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Study of Pulsed Laser Micro Polishing written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fundamental study of pulsed laser micro polishing (PLμP) was conducted as a method for reducing surface roughness of micro/meso-scale metallic parts. Although PLμP was shown to be an effective process at these scales, the knowledge of the process physics lacked thoroughness. The goal of this work, therefore was to improve upon the existing knowledge of PLμP, with focus on developing physics based models, understanding the effects of various process parameters and developing strategies for selection of process parameters and laser scan trajectories. In PLμP, a small area on a surface is irradiated with laser pulses to melt roughness features. The molten features are smoothed out by surface tension and viscous forces. Two polishing regimes for PLμP, namely thermocapillary regime and capillary regime, were defined based on whether the temperature gradient of surface tension driven thermocapillary flows are dominant or negligible. Dominant thermocapillary flows, in the thermocapillary regime, result in significant smoothening of both low and high spatial frequency features, but introduce residual low-amplitude high spatial frequency features. In the capillary regime, thermocapillary flows are negligible and the molten features oscillate as stationary capillary waves that damp out due to the viscosity of the molten metal. The capillary regime is only effective at smoothening higher spatial frequency features. A physics based surface finish prediction model was developed and validated for the capillary regime. The fundamental understanding of the two polishing regimes lead to the development of a two-pass multi-regime PLμP method that takes advantage of both the polishing regimes. In this method, the first pass, in the thermocapillary regime, results in significant reduction of the surface roughness. The second pass, in the capillary regime, removes the residual process features introduced in the first pass. Finally, an artificial potential fields based method was proposed to generate laser scan trajectories for PLμP that can overcome the limitations of a zigzag trajectory. In this method, artificial attractive fields are assigned based on surface condition and repulsive fields assigned to regions where polishing is not desired. The generated trajectories are irregular, smooth and adapt to the changing surface condition of surface being polished.

Download or read book Laser Surface Treatment of Metals written by C.W. Draper and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Study Institute, San Miniato, Italy, September 2-13, 1985

Download or read book Study of Surface Melting of Metals and the Effects in Pulsed Laser Micro Polishing written by Chao Ma and published by . This book was released on 2012 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Modification and Alloying written by J.M. Poate and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an outcome of the NATO institute on surface modification which was held in Trevi, 1981. Surface modification and alloying by ion, electron or laser beams is proving to be one of the most burgeoning areas of materials science. The field covers such diverse areas as integrated circuit processing to fabricating wear and corrosion resistant surfaces on mechanical components. The common scientific questions of interest are the microstructures by the different energy deposition techniques. and associated physical properties produced The chapters constitute a critical review of the various subjects covered at Trevi. Each chapter author took responsibility for the overall review and used contributions from the many papers presented at the meeting; each participant gave a presentation. The contributors are listed at the start of each chapter. We took this approach to get some order in a large and diverse field. We are indebted to all the contributors, in particular the chapter authors for working the many papers into coherent packages; to Jim Mayer for hosting a workshop of chapter authors at Cornell and to Ian Bubb who did a sterling job in working over some of the manuscripts. Our special thanks are due to the text processing center at Bell Labs who took on the task of assembling the book. In particular Karen Lieb and Beverly Heravi typed the whole manuscript and had the entire book phototypeset using the Bell Laboratories UNIXTM system.

Download or read book Equipment Recommendations and Experimental Studies Towards Automation of Friction Stir Welding and Pulsed Laser Micro Polishing written by Dennis Marc Wolf and published by . This book was released on 2009 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Surface Finishing and Deburring Technology written by Hang Gao and published by Trans Tech Publications Ltd. This book was released on 2007-09-10 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume is indexed by Thomson Reuters CPCI-S (WoS). Enhancement of the surface finish and integrity of engineered components is increasingly important, particularly for the working parts used in electronic and optical devices and systems. Significant progress has been made, in recent years, in developing new and advanced surface finishing technologies as well as in achieving a fundamental understanding of surface finishing technologies in order to predict, control and optimise practical surface finishing processes. The aim of this special volume is to offer the opportunity of bringing together academic researchers and industry workers in order to exchange information on the latest developments in, and applications of, advanced precision surface finishing and deburring technologies; as well as generally promoting personal contact and interdisciplinary research collaborations.

Download or read book Polishing Metal Surfaces for Optical Purposes written by William Frederick Steve and published by . This book was released on 1907 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling the Laser Induced Phenomena and Spall Failure of Metal Microstructures at the Atomic Scales and the Mesoscales written by Sergey Galitskiy and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The understanding of laser-induced phenomena in metals plays a critical role in pushing the current state-of-the-art in nanoscale laser processing methodologies (drilling, welding, surface structuring, etc.) and providing insights into the mechanisms of dynamic strength of materials. These techniques operate at small temporal and spatial scales (picoseconds and nanometers), often inaccessible with the experiment. The modeling approach can provide valuable insights into microstructural evolution at such scales. However, an accurate description of laser-matter interaction and lattice phenomena is challenging. This dissertation aims to develop and apply a novel modeling methodology to investigate the evolution of microstructure due to laser-induced phenomena at the atomic scales and the mesoscales. The developed mesoscale-continuum Quasi-coarse-grained Dynamics – two-temperature model (QCGD-TTM) combines an accurate description of laser energy absorption at nanoscales (within the TTM frame) and extends the domain of its applicability from nanometers to several microns by integration of QCGD. The developed model is used to determine the role of microstructure (orientation, grains, porosity, nanoscale geometry) in laser-induced melting and shock phenomena in metals. Chapter Two utilizes MD-TTM to investigate the behavior of nanoscale Al microstructures irradiated by ultrafast (femtoseconds) lasers. The formation of the shock wave, its propagation, and consequent material failure (spall) is studied for a range of orientation, grain structure, and laser parameters. It is demonstrated that elevated temperatures and defect density are the major factors determining the ability of a metal to withstand failure in extreme shock loading conditions. In Chapter Three, the mesoscale QCGD-TTM approach is developed and used to extend the investigation of spall phenomena in Al to micron scales. The coarser microstructure (grains) and larger system size reduce the spall strength and exhibit the conditions for partial fracture (incipient spall). The interaction of the incipient spall with secondary shockwaves facilitates damage healing by void volume reduction. Chapter Four investigates the role of porosity (voids) during shock. The interaction of mesoscale voids with shockwaves is studied in BCC single-crystal Ta using QCGD. The dynamics of void collapse and its influence on the microstructure and spall are characterized at various shock-loading conditions and porosity distribution. Chapter Five further develops MD/QCGD-TTM by implementing laser absorption models to accurately predict the microstructural evolution in complex nanoscale geometries. The model is used to study the laser melting in small (nanoscale to micron) Al particles at regimes close to the ablation threshold. The demonstrated dynamics of melting and consequent solidification of Al particles irradiated by pulsed laser suggest guidelines for surface nanostructuring techniques. This dissertation provides a versatile QCGD-TTM modeling framework to predict the microstructural evolution of metals at the nano and mesoscale. The model can be further utilized to study microstructural evolution in metals (shock phenomena, phase transformation, defect evolution, etc.) at the scales of a modern experiment, therefore, assisting the development of laser-based techniques.

Download or read book Applicability of a Picosecond Laser for Micro polishing of Metallic Surfaces written by Abdullah Mohammad Khalid Hafiz and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An increasing number of recent technological advancements is linked to the adoptions of ultra-short pulsed picosecond (ps) lasers in various material processing applications. The superior capability of this laser is associated with precise control of laser-material interaction resulted from extremely short interaction time. In this context, the present study explored the applicability of a ps laser in laser micro-polishing (LæP) of Inconel 718 (IN718) and AISI H13 tool steel. The melting regime-a mandatory phase for LæP-was determined experimentally by the variation of focal offset to attain desired laser fluence. The finite element formulation of heat transfer equation and its solution were also estimated in order to develop a theoretical foundation for the heat transfer mechanism in ps laser-material interaction. The initial one dimensional (1D) line polishing experiments were performed on ground IN718 and H13 tool steel samples with the parameters related to the melting regime of corresponding material. The knowledge of this initial experimental investigation was later utilized to prepare the surface topography by micromilling with a specific step-over and scallop height, followed by LæP experiments with the same set of aforementioned parameters. The performance of LæP was evaluated by average surface roughness (Ra) spectrum at different spatial wavelength intervals along the laser path trajectory. Additionally, statistical measures, such as power spectral density (PSD) function, transfer function (TF) and material ratio (MR) curve were analyzed in order to establish the process parameters resulting the best possible surface quality. From the analysis of this experimental investigation, surface quality improvement up to 78.5% and 75.7% were reported for the spatial wavelength interval of 50-100 æm for IN718 and H13 tool steel respectively. As a next step, two dimensional (2D) areal polishing of micromilled IN718 and H13 tool steel were performed, where surface quality improvement up to 69.32% and 77.28% were observed for the spatial wavelength interval of 50-100 æm for IN718 and H13 tool steel, respectively. Overall, ps LæP was found to be an effective way of enhancing desired surface quality as demonstrated by the reduction of surface asperities as well as their volumetric uniform redistributions.

Download or read book The Electrolytic and Chemical Polishing of Metals in Research and Industry written by W. J. McG. Tegart and published by . This book was released on 1956 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modification of Surface Tribological Properties by Microscale Pulsed Laser Processing written by Shixuan Chen and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When a microscale pulsed laser beam deposits localized energy on a metallic surface, the irradiated spot can melt and cool down rapidly. A scanned surface area experiences a cycle of rapid heating and cooling treatments, which in turn causes microstructural evolution. The microstructural evolution leads to changes in mechanical strength and tribological properties. Besides, microscale pulsed laser processing controls micro-scale surface features. Therefore, it is a promising technique to produce surfaces with improved tribological performance. The objective of this thesis is to investigate the microstructural changes and the multi-scale tribological performances of the microscale pulsed laser processed surfaces. The tribological performances are related to the microstructures to understand the underlying mechanisms of the enhancements. The thesis starts with applications of microscale pulsed laser processing on a couple of metallic alloys to study the microstructural changes in the processed area, such as phase transformation and chemical redistribution (Chapters 2 and 3). Initially, this method is applied on Ti6Al4V alloy to create continuous surface layers with altered phase components. Two laser powers are used to achieve low and high energy inputs. The obtained phases are predominantly martensitic Îł' and Îø phases due to the extremely rapid heating and cooling in the melt zone and heat affected zone. Higher laser power produces thicker martensitic Îł' surface layers several microns into the processed surface, exhibiting higher hardness compared to the surface processed by low power laser. The hard martensitic surface layer resulting from microscale pulsed laser processing facilitates superior resistance to abrasive wear and low cycle fatigue wear. Then, the influence of microscale pulsed laser processing on chemical distribution and wear resistance of A384 casting aluminum (Al) alloy is investigated. The large proeutectic silicon (Si) precipitates in the base material melt and disperse into the Al matrix during melting. Thanks to the rapid cooling, the dispersed Si lacks time to grow. Thus, the process results in a homogeneous remelted surface layer with well-distributed small Si particles. The hardness of the layer becomes more uniform compared to the base material, which is an expected consequence of elemental homogenization. Besides, the hardness and wear resistance of the homogeneous surface is higher than the unprocessed Al matrix. Microscale pulsed laser processing can also cause significant geometric and chemical changes in a multi-material system. Chapter 4 and 5 of this thesis study those changes on S7 tool steel surfaces dip-coated by nanoparticles and melted by microscale pulsed laser. The nanoparticles can either mix with the substrate or agglomerate on the surface, depending on the laser settings and nanoparticle properties. The magnitude of the fluid flow in the melt pool increases as the laser power increases. Higher laser powers result in stronger flow of the molten mix and help mixing of nanoparticles in the substrate. Besides, nanoparticles with good wettability, solubility and reactivity with the substrate can mix with the substrate and form alloyed regions; whereas nanoparticles with poor wettability agglomerate on the surface and form clusters. For instance, thanks to their good wettability and solubility in steel, SiC nanoparticles mix with the S7 tool steel during processing and form alloyed regions. The alloyed regions exhibit higher hardness and wear resistance compared to the substrate processed without nanoparticles. That enhancement should come from the strengthening effect of the nanoparticles dispersed in the metal matrix. In contrast, due to the poor wettability in liquid iron, Al2O3 nanoparticles form clusters on the S7 tool steel surface after microscale pulsed laser processing. The clusters exhibit higher hardness, denser structure and stronger bonding to the substrate compared to the as-coated layer. Therefore, the clusters can withstand severe scratching and exhibit excellent wear resistance. In this study, microscale pulsed laser processing is applied on metallic surfaces to achieve enhancement of the multi-scale tribological properties. The enhancement can be realized by altering the phase component, chemical distribution and introducing reinforcements. The method is flexible with the scale and the selection of the processed material, therefore has a great potential in micro device and small part manufacturing.

Download or read book Metallographic Polishing by Mechanical Methods written by Leonard Ernest Samuels and published by ASM International(OH). This book was released on 2003 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quality and usefulness of micrographs depends greatly on the preparation and polishing of metallographic specimens, and the work of Leonard Samuels has been instrumental in achieving a more scientific understanding of the effects and mechanisms by which materials is removed during preparation of metallographic specimens. This book provides comprehensive and authoritative coverage of mechanical polishing methods. The 4th Edition covers the advances that have been made since the 3rd Edition was published in 1982. These advances have enabled manual preparation procedures to be reassessed, with the result that considerable simplifications have become possible. Major advances have also been made in the development of semi-automatic machines, and preparation procedures over the last few years, with the objective of increasing productivity and improving reliability. These processes use abrasive machining devices that are significantly different from those used in manual procedures, which are also discussed, but necessarily in a more limited way than for manual procedures because less basic information is available. Other updates and clarifications have been provided throughout the book to create a complete, easy-to-use, and up-to-date information resource on this topic. Contents: Introduction; Sectioning and mounting; Principles of machining with abrasives; Practice of machining with abrasives; Surface damage from machining with abrasives; Non-abrasive machining; Polishing with abrasives: principles; Polishing with abrasives: surface damage; Brittle materials: principles; Principles of the design of manual preparation systems; Modifications required to manual preparation systems.; Semi-automatic polishing; Glossary; Index.

Download or read book Conduction mode and Keyhole mode Laser Polishing of Additively Manufactured Cobalt Chromium Surfaces written by Brodan Mark Richter and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Additive manufacturing (AM) has been the subject of rapid growth and study in recent decades due to the design flexibility and improved capabilities the process enables for manufacturers. However, AM surfaces are usually quite rough with a poor surface quality that necessitates surface post-processing to make them suitable for industrial use. One technique, laser polishing, has been effectively used on a variety of additively manufactured metallic surfaces and has typically reduced the roughness by more than 90%. However, these studies often only study one roughness parameter of interest, do not discuss in detail the effect of the different processing parameters on the final surface, and observe residual waviness in the final laser polished surface.This work helps address those challenges through various studies examining the laser polishing of cobalt-chromium AM surfaces. The first portion of this work (℗ʹ3 and ℗ʹ4) explores various aspects of conduction-mode laser polishing on AM components, including the efficacy of various surface texture parameters at distinguishing laser polished versus as-printed and ground surfaces, the influence the laser parameters have on smoothing, and the efficiency of various processing metrics at forecasting the resultant laser polished surface. To help provide greater reductions in the residual waviness often observed after laser polishing AM parts, the second portion of this work (℗ʹ5 and ℗ʹ6) proposes and studies an unexplored laser polishing technique - keyhole-mode laser polishing. The influence of the keyhole-mode on surface wave dynamics is analyzed through high-speed x-ray imaging performed at the Advanced Photon Source. The improved smoothing potential of the keyhole-mode is demonstrated through a detailed experimental study examining the laser polishing of individual lines, single-pass areas, and multiple-pass areas. Overall, this work provides insight into improving conduction-mode laser polishing of AM components while also performing detailed exploratory work into a new polishing mode that has the capability of providing additional roughness reductions for high roughness starting surfaces. Collectively, it is hoped that the work within this dissertation provides valuable experimental data and process knowledge to users looking to optimize the technique as well as provide the groundwork for continued development into a new and promising processing mode.

Download or read book The Electrolytic and Chemical Polishing of Metals in Research and Industry written by William John McGregor TEGART and published by . This book was released on 1956 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Induced Surface Contaminant Removal written by Abhishek Anant Dixit and published by . This book was released on 2010 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Roughness Prediction and Effects of Initial Surface Textures for Pulsed Laser Micro Polishing of Metal Alloys written by Qinghua Wang and published by . This book was released on 2015 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: