Résumé:
Our study concerns the tribological behavior of bronze-graphite, copper-graphite and graphite-graphite couples in a dry sliding contact with and without electrical current. We conducted experimental trials to determine the coefficient of friction, wear and temperature in the vicinity of the contact as a function of mechanical and electrical parameters. Starting from the Bowden and Tabor, we have calculated friction coefficient and using the Archard’s e have determined the wear rate of the pin. Measurements of the temperature change in the pins instrumented of thermocouple lead to estimate the heat flow in the pin. The distribution of the temperature field in the pin-disk geometrical area is obtained with a numerical method based on finite volume elements. It is important to know the type and magnitude of mechanical stresses imposed at the contact dynamics. To do this, a modeling based on quasi-analytical solutions was developed by a Matlab program.
The discussion of results is based on observations and analyzes of worn surfaces of the contact elements. These analyzes show that the electric current has a significant influence on the nature, composition and the growth rate of the oxide layer. The mechanism of formation and rupture of the film govern the tribological behavior, especially in the presence of electrical current. The analysis of the electrical contact resistance shows the cyclical growth and rupture of this film. This study also optimizes operating conditions tribocontacts, with and without electrical current, to increase the life of these couples and make a wise choice for best couple.
