Chemical Characterization of Tribological and Biomaterial Surfaces With Nanoscale Spatial Resolution.

摘要

The overall goal of this study is to gain molecular-level understanding of the chemical properties of the diamond like carbon (DLC) surface exposed at various environmental conditions so that this knowledge can be used to design better DLC coatings and operation conditions. DLC coatings have great potentials to reduce frictional energy loss and increase service life of mechanical systems. However, the near-frictionless and near-wearless behaviors are observed only in vacuum or extremely dry conditions. Our contributions toward the understanding of tribochemical properties of DLC coatings include elucidation of the friction reduction mechanism of hydrogen gas for hydrogen-free DLC coatings, in-situ characterization of the graphite- like transfer film, quantification of the oxidized surface layer and composition on DLC upon exposure to air, the adsorption isotherm of water on DLC in humid air, development of a theoretical model to predict the capillary force at nano-asperity contacts in ambient conditions, and discove1y of the vapor phase lubrication method to suppress the wear of DLC in humid air conditions.