Effect of Corrosive Environment on Friction Characteristics of Brake Friction Materials

The friction properties of brake friction materials are investigated utilizing the different car cleaners. Water, wheel cleaner and tire dressing were used to designate driving conditions in the field. The friction materials were soaked in each solution before friction test. The Coefficient of friction (COF) was similar in the case of water and tire dressing due to a same menstruum. And, the effect of surfactants within wheel cleaner caused lowest the COF. Surface morphologies were measured using confocal microscope and wheel cleaners, showing significant effects on the formation of thick and even friction film. The hardness of friction film was measured through micro-Vickers test, and the specimen with wheel cleaner showed highest hardness due to the thick film. On the other hand, the specimens with water and tire dressing showed a lower hardness even though the film was thicker than specimen with dry condition. The components of wheel cleaners also affected the hydrophobicity of friction films for both disc and pad. Therefore, the contact angle was critically low compared to other specimens. The reduction of hydrophobicity caused by the solution effects increasing of rust occurring on the surface of the brake disc. This result suggests that the formation of friction film under different environments was deeply related to friction and corrosive properties of brake system.