Tribological Performance and Failure Mechanism of Paper-Based Friction Materials Sliding against Steels of Different Carbon Contents

Paper-based friction material was prepared by wet-forming assisted hot-pressing process. The compatibility of steel pairs with different carbon contents and paper-based friction materials in oil-free state and oil-rich state was investigated, respectively. The friction mechanism in oil-free and oil-rich state was also discussed through wear surface analysis. Results showed that in the oil-free state, as the hardness of the matching material increased, the friction coefficient of the paper-based friction material decreased, the friction stability increased, and the wear rate decreased. The 65Mn steel with high hardness had better compatibility with paper-based friction materials. The failure mode of paper-based friction material in the oil-free state was fiber debonding and pulling-out caused by fatigue cracks. In the oil-rich state, the hardness of the steel had no significant effect on the tribological properties of the paper-based friction material. The formation of oil film and friction film effectively reduced the micro-cutting effect on the material, and hereby reduced the wear of the material.