Adhesion between nanoscale rough surfaces. I. Role of asperity geometry

Nanoscale surface roughness strongly affects the adhesion force between surfaces. In this investigation, a model that more accurately describes the size of an asperity based on the measurable parameters of root-mean-square (rms) roughness and the distance between the asperities is derived. The radius of the asperity from the proposed model is much larger than the radius used in previous approaches, considering the same surface with nanoscale roughness. Using the proposed geometry and previously suggested models, this paper elucidates the contributions from contact and noncontact interactions of a particle adhered to a surface with nanoscale roughness (approximately less than 20 nm rms). For most surfaces considered, the contact interaction of the asperity and the adhering particle are found to dominate the interaction. In the second paper of this series, the proposed model is compared to the experimentally determined force of adhesion in systems with nanoscale roughness. (C) 2000 Academic Press.