Surface-topography assessment: precursor to the prediction of pressed-contact behaviour

The deformation mechanisms ensuing when a contact between two nominally-flat surfaces is subjected to mechanical and thermal stresses have been examined and the surface properties essential for the prediction of the contact's behaviour identified. These parameters include: the surface micro-hardness (in order to estimate the total true area of contact); the root-mean-square roughness as well as the mean absolute asperity-slope (so as to be able to predict the number and mean size of micro-contacts); the mean radius of curvature of the asperity peaks (which will help to indicate whether the surface deformations will be predominantly plastic or elastic); and surface wavelength parameters, such as autocorrelation and power spectral density functions (which are needed to estimate how micro-contact populations cluster at contacts formed between wavy surfaces). Various methods for surface-topography assessment and appropriate data manipulation in order to deduce values for meaningful parameters are described.