The research objectives of this work are to complete development of a fluctuating-charge molecular dynamics code and potential energy function that are capable of reliably capturing bond breaking and forming events that occur between carbon-based materials and oxygen-containing environmental species, such as water. The phrase "carbon-based materials" encompasses a broad range of materials, including the building blocks of biology, allotropes of carbon, and carbon-based films. Because carbon-based solid lubricants have desirable properties, such as high hardness and ultralow friction and wear, they are being used or considered for a wide range of applications that include space systems, micro-electromechanical systems, orthopedic implants, computer hard disks, and as scaffolds on which to build DNA-based microsensors. Perhaps the most significant factor that has prevented even wider spread use of carbon-based materials as solid lubricants is the sensitivity of their friction to the environment. This project will also validate a potential energy function based on a similar formalism that can model dynamics in Si-, C- and H- containing systems. Knowledge gained from these development projects can be used to create a potential capable of modeing chemical reactions in Si-, O- and H- containing systems with charge. These tools can then be used to examine the nanotribology and mechanical properties of carbon-based material in the presence of water, the properties of Si-doped DLC, and epitaxial graphene on Si-C.
If successful, this research effort will provide several new tools that can be used to examine dynamics at the atomic scale. In addition, a fundamental understanding of the way in which environmental species, such as water, impact carbon-based solid lubricant performance will be developed. This knowledge will allow for the rational design of carbon-based solid lubricants with the desired tribological and mechanical properties and increase the viability of applications where carbon-based solid lubricant films can be used. Also as part of this project, a broad range of middle and high school students will be introduced to nanotribology via the integration of a nanotribology module into the existing USNA STEM program and into the DAPCEP program at OU. Nanotribology modules will also be developed for graduate-level tribology classes at OU.