Understanding the Friction Instability of the Brake Friction Material Based on a Stress-Assisted Kinetic Model of Plateau Formation on the Sliding Surface

Friction instability occurred during sliding is studied by investigating the construction and destruction rates of contact plateaus at various sliding conditions. The friction material specimens that are similar in the friction level but showing different stick-slip characteristics were used for this study. Results showed that the friction level was governed by the relative contribution of the primary and secondary contact plateaus present on the sliding surface, which also affected the specific wear rate of the brake friction material. The friction material specimens with the high wear rate showed a considerable increase in the area of secondary contact plateaus, causing a large amplitude of stick-slip. The velocity weakening of the friction coefficient, which was known to be closely related to the noise propensity of a brake lining, was also determined by the growth and deformation of the secondary contact plateaus, which was supported by the stress-assisted kinetic model for wear particle plateau formation.