Boundary Lubrication and Surface Dynamics

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Abstract 0510239There is a longstanding need for self-lubricating materials for mechanical systems such as gyroscopes, motors, and unmanned space vehicles, in which maintenance-free operation is required over long periods of time. An even greater need exists for these materials for micro- and nano-electro-mechanical systems (MEMS and NEMS) assemblies earmarked for myriad applications in nanotechnology, including actuators for microwave switches and robotics and "intelligent" sensing and drug delivery equipment. In these applications, the miniature scale of the devices increases their surface-to-volume ratio, enhancing the likelihood that premature mechanical failure results from accidental contact of moving surfaces. To design an effective self-lubricated material, it is necessary that lubricant molecules possess high surface mobility, so that the dynamic friction coefficient of the surface is low. This requirement must be balanced against the known tendency of adsorbing substrates to slow down motion of molecules and thereby reduce their effectiveness as lubricants. The research proposed uses a combination of experiment and theory to improve current understanding of molecular mobility and lubrication properties of surface coatings possessing controlled levels of molecular disorder. The investigators propose to exploit this understanding to develop novel lubricant coatings suitable for micro and nano-sized mechanical systems.