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Title:Tribological studies of micro/nanoscale thin solid films
Author(s):Lee, Jungkyu
Director of Research:Polycarpou, Andreas A.
Doctoral Committee Chair(s):Polycarpou, Andreas A.
Doctoral Committee Member(s):Bergman, Lawrence A.; Abelson, John R.; Chasiotis, Ioannis
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):tribology
thin film
wear
coating
Abstract:Use of thin films has received significant attention in recent years because of their advantages in controlling friction and wear of the bulk material. There have been significant advances in modern applications such as in magnetic disks for data storage and microelectromechanical systems (MEMS) with the introduction of thin solid films coated on substrates. However, due to harsh operating conditions and higher performance requirements, it is necessary to explore new materials and develop experimental and theoretical framework to better understand the coating system. In this work, five different topics in regard to thin solid films have been studied. First, the adhesion behavior of thin film layers in contact with a solid under shearing motion was investigated. Experimental results of pull-off adhesive forces using various coating materials show that adhesion can be controlled by choosing different coating materials with the aid of appropriate shearing force. Second, the mechanical and tribological properties for a novel material, La5Ca9Cu24O41 (LCCO), were evaluated, revealing that LCCO can be an attractive candidate as a nanothermal layer showing good tribological characteristics as well as thermal properties. Third, the contact behavior of thin films coated on substrate was investigated using a nanoindentation tester and a dynamic stiffness tester. When a hard layer is coated on a soft substrate, both asperity interaction and soft substrate deformation should be considered. Fourth, the wear behavior of a layered sphere at the sliding inception was analyzed based on the finite element approach. The relationships among potential wear, material properties, and normal load were obtained. Fifth, the yielding behavior of hafnium diboride (HfB2) hard coatings was studied showing that plastic deformation at the interface was the dominant failure mechanism of the HfB2 films.
Issue Date:2012-06-27
URI:http://hdl.handle.net/2142/32008
Rights Information:Copyright 2012 Jungkyu Lee
Date Available in IDEALS:2014-06-28
Date Deposited:2012-05


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