Biography: Dr. Peng-Sheng Wei received Ph.D. in Mechanical Engineering Department at University of California, Davis, in 1984. He has been a professor in the Department of Mechanical and Electro-Mechanical Engineering of National Sun Yat-Sen University, Kaohsiung, Taiwan, since 1989. Dr. Wei has contributed to advancing the understanding of and to the applications of electron and laser beam, plasma, and resistance welding through theoretical analyses coupled with verification experiments. Investigations also include studies of their thermal and fluid flow processes, and formations of the defects such as humping, rippling, spiking and porosity. Dr. Wei has published more than 80 journal papers. He is a Fellow of AWS (2007), and a Fellow of ASME (2000). He also received the Outstanding Research Achievement Awards from both the National Science Council (2004), and NSYSU (1991, 2001, 2004), the Outstanding Scholar Research Project Winner Award from National Science Council (2008), the Adams Memorial Membership Award from AWS (2008), the Warren F. Savage Memorial Award from AWS (2012), and the William Irrgang Memorial Award from AWS (2014). He has been the Xi-Wan Chair Professor of NSYSU since 2009, and Invited Distinguished Professor in the Beijing University of Technology, China, during 2015-2017.
Topic: Defects Encountered in Keyhole Welding
Abstract: This presentation analyzes defects of (1) surface rippling and humping, (2) root spiking, (3) pore formation, and (4) missed joint due to thermoelectric magnetism in electron beam keyhole welding. The defects of rippling, humping, spiking, porosity and missed-joint seriously reduce the properties and strength of the joint and products. We measure, analyze and confirm mechanisms of these defects. Controlling of these defects becomes achievable.
Biography: Dr. Hua Mei received her B.S. in Applied Chemistry in 1999 and Ph.D. in Organic Chemistry in 2006. Her graduate research project, mentored by Prof. Darryl DesMarteau at Clemson University, involved the synthesis of new organic fluorinated materials as photo acid generator for microlithography and as electrolyte for proton exchange membrane fuel cells. Dr. Mei worked as a visiting Assistant Professor at Loyola College in Maryland from 2006 to 2007, and as a postdoctoral research associate in the group of Prof. Josef Michl at the University of Colorado at Boulder from 2007 to 2009 focusing on organic Boron catalyst preparation for unsaturated olefin polymerization. Dr. Mei then worked as an Assistant Professor at Xavier University of Louisiana in New Orleans from 2009 to 2012, before moving to East Tennessee State University, where she has been working since 2012.
Topic: Diazonium (Perfluoroalkyl) Benzenesulfonimide Zwitterionic Monomers for Proton Exchange Membrane Fuel Cells
Abstract: A series of diazonium (perfluoroalkyl) benzenesulfonyimide (PFSI) zwitterionic monomers have been synthesized from perfluoro-3, 6-dioxa-4-methyl-7-octene-sulfonyl fluoride (Nafion®), and perfluoro-3-oxa-4-pentenesulfonyl fluoride (POPF) monomers for the first time. With trifluorovinyl ether and diazonium precursors, the partially-fluorinated diazonium monomers can be further polymerized and will provide chemically bonding with carbon electrode in Proton Exchange Membrane fuel cells. A systematic study of the synthesis and characterization of these diazonium PFSI monomers has been conducted. The chemical properties and thermal stability of these monomers have been measured and will be discussed in the seminar.