The Atomic Nature of Polymer-Metal Interactions in Adhesion, Friction, and Wear

Abstract

The polymers PTFE (polytetraf1uoroethylene) and polyimide were studied contacting various metals in adhesion and sliding friction experiments. Field ion microscopy and Auger emission spectroscopy, were used to examine the nature of the polymermetal interactions. Strong adhesion of polymers to all metals in both the clean and oxidized states was observed. Adhesive bonding was sufficiently strong with the cohesively weaker metals such as aluminum that metal transferred to the polymers. Adhesion coefficients measured approach those for clean metals in contact and field ion microscopy indicates that the polymer to metal bonds are chemical in nature. The field ion microscope also indicates that polymer fragments transferred to cohesively strong metals such as tungsten and that these fragments are highly oriented. Auger emission spectroscopy indicates that a single pass of PTFE across a metal surface is sufficient to generate a transfer film. Electron induced desorption of the PTFE from the metal surface indicates that bonding to the metal is via the carbon atom with little to no fluorine to metal interaction.