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Title: Tribology of organic self-assembled monolayers (SAMs) and thin-films on Si Surface
Keywords: friction, wear, lubrication, SAMs, polymer film, MEMS
Issue Date: 16-Nov-2007
Citation: SATYANARAYANA NALAM (2007-11-16). Tribology of organic self-assembled monolayers (SAMs) and thin-films on Si Surface. ScholarBank@NUS Repository.
Abstract: Silicon (Si), which is an important structural material for many microsystems (such as MEMS), suffers from several surface related tribological issues such as high friction, adhesion and wear during sliding and occasional contacts. Hence, in this thesis, we propose and investigate low friction and wear-resistant coatings based on organic SAMs and polymeric films for Si surface.Mainly two approaches are explored:(1) overcoating different SAMs with a top layer of perfluoropolyether (PFPE) which has shown low friction and very high wear-durability;(2) development of polymer thin-films with better tribological propertiesThe composite SAM/PFPE layer has demonstrated very high wear life on the Si surface in sliding contact compared to traditionally used only SAM coating. It is shown that PFPE, which forms nano-scale liquid-like layer, provides essentiallubrication and works better with a hydrophilic SAM [such as 3-Aminopropyltrimethoxysilane (APTMS) or 3-glycidoxypropyltrimethoxysilane (epoxy SAM)].Further in this research, novel coating procedures have been developed for the deposition of ultra-thin films (with exceptional wear-durability) of ultra-high molecular weight polyethylene (UHMWPE) and polyimide (PI) on Si surface. It has been demonstrated that the addition of filler materials such as CNTs shows excellent improvement in the wear-durability when they are added to the polymer films. The mechanisms responsible for high wear-durability of selected films are explained from their microstructure, chemical, physical and mechanical properties.
Appears in Collections:Ph.D Theses (Open)

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