VOLUME INCREASE PHENOMENA IN RECIPROCAL SCRATCHING OF POLYCARBONATE STUDIED BY ATOMIC-FORCE MICROSCOPY

An atomic force microscope (AFM) was used to study the microwear process of polycarbonate (PC). Testing included Line scratching of the polymer surface using a microfabricated Si3N4 AFM tip of 10-20 nm radius. Interfacial adhesion, friction, the effect of the number of scratches, and scanning speed were studied. Unlike previous reports, projections as a result of polycarbonate apparent volume increase have been observed after reciprocal scratching on the same track (without an AFM tip lateral feed). In spite of analytically predicted elastic/plastic contact, no plastic deformation was found during the tests. A model, based on the formation of cracks and their growth was suggested to explain these phenomena. No viscoelastic/plastic behavior (scanning speed effect on friction or microwear) was found. (C) 1995 American Vacuum Society.