Tribological behavior of a silicon carbide/carbone dry contact
Résumé
The development of new high-performance mechanical seals working in severe conditions requires higher material performances. Sintered silicon carbide (SSC), widely used as a hard mating material, is a potential candidate but its friction and wear properties need to be investigated in the scope of these new applications. Silicon carbide offers good mechanical properties (high hardness, high Young modulus), good corrosion resistance and good thermal conductivity, that make it suitable for tribological applications in different atmosphere (in air, argon or vacuum) and in dry or lubricated sliding. Combined with a counter-face ring made of a softer carbon-graphite, the dry sliding of SSC can be sustained even under severe conditions of pressure and speed. Graphite has been intensively studied in tribology since Bragg first described its lamellar structure. It has been thought during many years that graphite could act as a solid lubricant thanks to this structure. In fact, the environmental conditions strongly influence its tribological behavior. The hardness of the ceramic facing the carbon seal has also an impact on its friction properties. A transfer layer of carbon is generally found on the ceramic surface. In this study, a first experiment assesses the tribological behavior of SSC sliding against itself and three different carbon-graphite materials. Dry friction and ring-on-ring configuration are considered. A second test uses an infrared camera to estimate the temperature variations of a SiC/C couple during sliding, which determines relationship between displacement resistance and the heat generation.
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