Comparison of scanning electron microscopy and stylus raster measurements of wear

Abstract

In a simple running-in experiment a steel and a brass surface are in sliding contact. Measurements of their surface topography are made by scanning electron microscopy (SEM) and with a raster scanning system based on a stylus instrument. Histograms of height readings and isometric views produced by computer from the stylus data are compared with SEM micrographs, often on the same area of surface. Changes in microtopography of the steel are found to be too small for easy stylus measurement. A progressive increase in roughness of the brass surface ends with delamination, shown more clearly by the SEM micrographs than by the stylus technique. The stylus, however, gives area roughness measurements and shows the existence of deep valleys not easily measured by SEM. Comparison of results enables progressive changes in surface statistics to be related to changing surface appearance.