Nano and Micromechanics of Solid-Surface Composites for Contact Suspensio
Kyung-Suk Kim
2:30 PM on 2008-02-22
Over the past decade, rapid advancement in nanotechnology has made it possible to design solid-surface composites to suspend liquid molecules, biological cells as well as plastically deforming solid surfaces. Suspension of liquids and bio cells has already been studied extensibly for designing effective super-hydrophobic surfaces that can be applied to new technologies such as water harvesting from environmental air, nano/micro scale water/liquid management in renewable energy technology, manipulation of biological cell adhesion for cell-growth control in biomedical applications and bio-nanotribology for friction and wear controls as well as for boundary-layer drag reduction. Recently fundamental studies on nano/micro-scale solid surface suspension have been carried out by our research group of the Nano and Micro Mechanics Laboratory at Brown. In particular, nano and micro mechanics framework of solid-surface composites for contact suspension have been developed with various scale-bridging concepts. This framework is particularly important for advances in nano and biotechnology because most of super-hydrophobic surface structures and solid surface suspension nano-structures require feasibility of mass-production and durability for their applications. In this talk, recent studies on the effects of nanometer scale roughness and Al/Si in-situ surface composite structures on solid surface suspension will be presented. The nano-roughness effectively suspends contacting surfaces under pressure, since solids are very strong at the small scale. Nevertheless, certain adhesion mechanisms can amplify the contact pressure to flatten the roughness, increasing friction. For example, a gold nano-bump is twice harder than ultra-high-strength steels; however, it could be flattened by water capillary adhesion. Al/Si in-situ surface composite structures are used for linerless aluminum engines for light weight engine design. A hybrid method of nano-indentation and finite element analysis has been developed with a concept of nano and micro mechanics scale bridging for the optimal design of Al/S surface composite structures for solid surface suspension.