Nano-Mechanics of Solid Surface Suspension and Imprinting

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Nano-mechanics of solid surface suspension and imprintingKyung-Suk Kim, Professor of EngineeringBrown University, Providence, RI 02912Given a high density of nails per square inch, a person is able to lie upon a bed of nails without harm, as the body of the person is suspended on the nail contact points. However, if enough pressure is applied, the nails will pierce the skin surface. This phenomenon can also be observed at the nanometer-scale. Under certain conditions, a solid surface is suspended on a dense array of nanostructures while at other conditions, the surface is imprinted by the nanostructure array. In this project, the investigator and his colleagues study nanometer-scale solid surface deformation associated with solid surface suspension and imprinting caused by high grafting density contacts and molecular interactions at the interface. Carbon nanotube arrays of high grafting density, greater than hundred million arrays per square millimeter, are used to study nanoscale contact suspension of plastically deforming solids and imprintability of high density nanoscale contacts. The study is motivated by the need to develop effective technology for fabricating surface nanostructures and intended to further understanding of nanoscale friction and wear. The former includes nano-imprinting as well as nano-planarization of gold molds for nano-imprinting lithography. Nano-imprinting lithography can not only produce extremely small features but greatly simplify many production processes and lower production cost substantially. The semiconductor industry is currently developing nano-imprinting lithography to build chips with circuits as narrow as 30 nanometers width or less. The latter comprises mainly solid lubrication with nanostructures for dry machining. Dry machining, without liquid lubricant, is necessary to build environmentally-safe manufacturing infrastructures for mass production of lightweight structures. The automotive industry is currently developing a nano-structured coating on tool surfaces to machine aluminum parts with the dry friction coefficient as low as 0.02 or less.The intellectual merit of the work is to provide fundamental understanding of mechanisms of contact interface deformation at the nanoscale and to establish a systematic framework for assessing reliability of nano-fabrication and the use of solid nanostructures. In terms of broader impact, Stan Williams of Hewlett-Packard has stated, "imprint technology has the potential to revolutionize the semiconductor industry as well as a host of other fields, from data storage to optical networking to life sciences," indicating potential major impact on information technology as well as on nano-technology. In addition, it will make broad impact on bio and environmental technology with surface nano-structure sensors and filters, and on materials, manufacturing and energy technology with nanostructured carbon-based coatings for dry machining of light weight structures. Also under this project, it is planned to educate under-represented REU students through summer internship programs and to develop a new course in the field of nanomechanics.