Electrical Conductance of Oxidized Rough Sphere Contacts: A Greenwood-Tripp-Based Model

Overview & Synopsis

Electrical conductance of rough contacts is strongly affected by the presence of surface oxides, particularly when oxide films are discontinuous and no clear separation of length scales exists between roughness, oxide morphology, and contact size. In this work, we develop a statistical model for electrical conductance in oxidized rough sphere contacts. Oxide films are represented as spatially heterogeneous insulating regions generated by thresholded Gaussian random fields, allowing controlled variation of oxide coverage and correlation length. Mechanical contact is treated within a Greenwood-Tripp-based formulation, while electrical conductance is evaluated using Greenwood's constriction resistance model applied to the resulting population of conducting microcontacts. A comprehensive parametric study reveals the role of oxide morphology and allows to formulate a simple phenomenological model for the average conductance. This new model is in a good agreement with the extended Barber's model.