Laser Processing of Metals and Polymers

Abstract

A laser offers a unique set of opportunities for precise delivery of high quality coherent energy. This energy can be tailored to alter the properties of material allowing a very flexible adjustment of the interaction that can lead to melting, vaporization, or just surface modification. Nowadays laser systems can be found in nearly all branches of research and industry for numerous applications. Sufficient evidence exists in the literature to suggest that further advancements in the field of laser material processing will rely significantly on the development of new process schemes. As a result they can be applied in various applications starting from fundamental research on systems, materials and processes performed on a scientific and technical basis for the industrial needs. The interaction of intense laser radiation with solid surfaces has extensively been studied for many years, in part, for development of possible applications. In this thesis, I present several applications of laser processing of metals and polymers including polishing niobium surface, producing a superconducting phase niobium nitride and depositing thin films of niobium nitride and organic material (cyclic olefin copolymer).The treated materials were examined by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), atomic force microscopy (AFM), high resolution optical microscopy, surface profilometry, Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). Power spectral density (PSD) spectra computed from AFM data gives further insight into the effect of laser melting on the topography of the treated niobium. I owe my deepest gratitude to Dr. J. Michael Klopf from FEL team, who was beside me supporting my experiments. Any discussion I had with him has always been informative and helpful. Thanks for his encouragement and patience. He faced the challenge of a demanding student as I was. Eventually my progress will inspire many more research students to seek his fortunate advice and guidance. I wish to thank Dr. Shukui Zhang from FEL team for training and teaching me the laser system. I can never forget the timely help rendered by Dr. Gwyn Williams, Dr. Steve Benson, Dr. Jim Coleman, Cody Dickover, Chris Gould, Joe Gubeli, Kevin Jordan, Jim Kortze, Dan Sexton, Dr. Michelle Shinn, Dr. Richard Walker, Tom Powers and Guy Wilson, during my stay in FEL building by providing all the help I requested for.