Tribological characterization of silicon carbide and carbon materials

Abstract

Tribological properties of a silicon carbide homogeneous contact are often related in lubricated or even dry conditions but only for ball or pin-on-disk configurations. In this study, we developed an experiment with a ring-on-ring configuration under dry friction in order to better match the industrial needs for dry mechanical seals applications. Tribological tests were run at a temperature of 120 °C, a sliding speed of 2 m/s and a contact pressure of 0.15 MPa on SiC/SiC and SiC/C pairs, with different impregnated carbon materials. Friction coefficients and wear were measured. The measurements were very sensitive to the formation and the circulation of the third body at the contact interface. This third body was mainly composed by carbon, oxygen and the carbon impregnants. An amorphization process of the tribofilm was revealed by using Raman spectroscopy. With EDS chemical analysis and the study of mechanical stresses by Raman spectroscopy the wear mechanisms were found to be driven by cracking process and oxidation.