Friction and wear behavior of engineering materials in a simulated Martian (CO 2) environment, a preliminary study

Abstract

The friction and wear behavior of materials (primarily metals) is a strong function of operating environment. Ambient conditions provide a natural lubricating oxide on most metals that reduce friction and wear. In vacuum metals have been shown to have friction coefficients exceeding unity with significant adhesive forces. In space applications materials must be designed with adequate solid lubrication to prevent wear and seizure. In between total vacuum and STP lies the surface of Mars with a primarily CO 2 atmosphere at 10–15 Torr (∼1% earth's atm.). Recent exploration missions conducted by NASA involved a wheeled craft navigating the rocky, dusty surface (opportunity and spirit rovers). The materials used in these rovers were tested in dry nitrogen only. This preliminary study measures friction and wear behavior of several materials utilizing an atomic force microscope and a pin on disk wear tester in a controlled environment of air, CO 2 and nitrogen at 760 Torr. The objective was to demonstrate if friction and wear in CO 2 and N 2 are comparable and whether a difference can be measured. Wear surfaces were examined using scanning electron microscopy. Results indicated some change in frictional force and wear in the CO 2 atmosphere.