Mesoscale Contact Characteristics under Current Transfer

Sliding metal-on-metal wear experiments were conducted at the meso-scale within a controlled environment chamber to evaluate the influence of current density, polarity, and humidified gas on system wear behavior. A meso-scale friction tester (MFT) was modified by enclosing the apparatus with an environmental chamber used for introducing humidified gases. Additionally, a high capacity direct current precision power supply was used to supply current through the contact interface of the test materials. Wear rates were observed to decrease with increasing levels of humidity. This observation is in agreement with previous experiments of this nature, but had not been conducted within this scale of measurement. Scanning electron microscopy (SEM) analysis of the wear areas and energy dispersive spectrometer (EDS) analyses suggest the possibility of micro arcing and melting during the evolution of the wear track. The static friction forces and the periods of stick slip were found to correlate with the grain size distribution. Experimental measurement of weld force and blow off force was found to correlate poorly with the theoretically predicted values, and could be attributed to scaling effects not included in the models.