Numerical descriptors for the analysis of wear surfaces using laser scanning confocal microscopy

Machinery wear is a major cost to industry and its minimisation would result in significant savings. in order to do this, it is important to understand the mechanisms of wear. Techniques have to be developed to enable the detailed measurement and analysis of wear surfaces. Conventional methods of surface measurement have involved profilometers. Profilometers, however, have severe limitations in terms of the surface features detectable and difficulties arise when 3D data sets of surfaces are required. Alternative methods that have been explored are stereo microscopy, reflected light interference microscopy (RLIM) and scanning electron microscopy. But these methods have proven to be severely limited either by the depth of field that can be obtained, difficulties associated with obtaining and interpreting images or the prohibitive costs involved. Laser scanning confocal microscopes (LSCM), however, have the capabilities to record surface features quickly and conveniently. LSCM techniques allow the determination and analysis of the true surface topography of a sample surface. LSCM has no depth of field limitations, is significantly cheaper than scanning electron microscopy, requires minimal sample preparation and provides images of sufficient quality for engineering purposes. Better measurement techniques facilitate the use of new surface parameters, in addition to the traditional parameters (all of which can be measured using LSCM techniques). In this paper, parameters developed for the measurement and analysis of surfaces using LSCM techniques are discussed. A comparison is made between surface analysis using LSCM techniques and conventional profilometer methods.