STUDY ON FRICTION AND WEAR BEHAVIOR OF COPPER FIBERS IN SEMIMETALLIC FRICTION MATERIALS

The friction surfaces of the friction pair consisting of the semimetallic friction material and cast iron were examinated by scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDX).The experimental results show that copper can transfer onto the friction surface of the cast iron counterpart by smearing,adhering and ploughing.Because of the smear and back transfer,the distribution of copper is more dispersive in the friction surface of the friction material after friction.However,there exists a lot of iron on the copper fibers in the friction surface of the friction material with iron and iron oxide wear debris adhering and mounting.These actions of the copper fibers make the friction pair have a stable friction coefficient and an excellent wear resistance.Moreover,the orientation of copper fibers has a great influence upon the friction and wear characteristics of the friction material.The coefficient of friction,wear loss and temperature at the friction interface where the fibers are perpendicular to the friction interface are lower than those at the interface where the fibers are parallel to the friction interface but perpendicular to the sliding direction.