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Abstract: Friction and wear characteristics of materials used in automotive/train brake systems play an important role for efficient and safe braking performance. Composites with exellent wear and friction performance are often used as the main brake pad material. In this study, a non-asbestos organic composite brake pad containing binder resin, solid lubricants, space fillers and friction modifier was developed, and its fiber content was optimized in order to achieve the best combination of tribo-performance and mechanical properties. For this purpose, different amount of fiber contents starting from 20 wt.% up to 40 wt.% were added to the composite’s matrix by adjusting only the barite content. Subsequently, the friction and wear behavior of the samples having adjusted amounts of fiber were analyzed using a pin-on-disc type friction material test machine (UTS Brake Pad Friction Tester). For this purpose, pin-type friction samples with the length of 15 mm and diameter of 20 mm were produced from the mixed composite. After tribological tests, the worn surfaces of the samples were scanned using a 3D surface profilometer to analyze the wear characteristic of the samples in detail. The results demonstrated that addition of fibers to the matrix structure caused a significant effect on the frictional characteristic of the composite. The average friction coefficient of composite showed a parabolic increase with increasing the fiber content. On the other hand, the stability of the friction coefficient changed during the wear tests with increasing the fiber content. The highest (40%) and the lowest (20%) fiber contents resulted in poor friction stability with high amount of flactuations in friction coefficent values. The best frictional stability was obtained in the composite containing 30 wt.% fiber. Therefore, a composite with 30% fiber was determined as the best content considering the performance parameters related to friction and wear. 3D investigations showed that the composite with 30 wt.% fiber had the best surfce friction film and also the lowest surface asperity.

Keywords: Brake pad composites, Friction and wear, non-asbestos organic composite for brake pads