MICROWEAR PROCESSES OF POLYMER SURFACES

An atomic force microscope was used to scan-scratch polycarbonate (PC), polymethyl-methacrylate (PMMA) and epoxy (EP) surfaces. A diamond tip with a radius of 0.1 mum was used for scratching and for profile measurements. The sample surfaces were scan-scratched with a load of 500 nN and three different feeds (50, 25 and 12.5 nm). The surfaces were also scan-scratched repeatedly with a load of 200 nN and a feed of 10 nm. The microwear process of PC, PMMA and EP were clarified from these experiments. (1) The microwear process of PC has three steps: the scan-scratched surface forms a plateau-like upheaval and no wear particles are produced (first step); the surface distorts to make projections and again no wear particles are produced (second step); and the surface is worn down and wear particles are produced (final step). (2) The microwear process of PMMA also has three steps, which are almost the same as those for PC. However, the deformation proceeds rapidly to destruction. (3) The microwear process of EP only has the final step. Wear particles are produced from the start. (4) The order of deformation is EP < PMMA < PC. However, the order of wear is EP < PC < PMMA. This suggests that the deformation of a material with a high elongation rate is large, but that the deformation rate is not related to the wear rate.