Fe及SiO2对铜基刹车材料摩擦磨损性能的影响机制.docx

Fe及SiO2对铜基刹车材料摩擦磨损性能的影响机制AbstractIn this study, the effects of Fe and SiO₂ on the friction and wear performance of copper-based brake materials were investigated. The influence mechanisms were analyzed through microscopic examination, X-ray diffraction (XRD), and mechanical testing. The results showed that the addition of Fe and SiO₂ could significantly improve the friction and wear resistance of the copper-based brake materials. The formation of an Fe-SiO₂ layer on the surface of the brake materials was the main reason for this improvement. The Fe-SiO₂ layer could effectively reduce the friction coefficient and wear rate by increasing the hardness and reducing the plastic deformation of the braking materials. This research provides a theoretical basis for the development and optimization of copper-based brake materials.IntroductionBrake materials are widely used in various machinery and transportation equipment, especially in automobiles. The performance of brake materials directly affects the driving safety and service life of the vehicles. Copper-based brake materials have good thermal conductivity, wear resistance, and mechanical properties, making them a popular choice for brake pad manufacturing. However, the friction and wear performance of copper-based brake materials still need to be improved, especially under high-temperature and high-load conditions.Fe and SiO₂ are widely used as additives in brake materials to improve their properties. Fe can effectively reduce the friction coefficient of brake materials and increase their hardness, wear resistance, and thermal stability [1, 2]. SiO₂ can improve the mechanical properties of brake materials and reduce their wear rates by forming a protective layer on the surface of the materials [3, 4]. In this study, we investigated the effects of Fe and SiO₂ on the friction and wear performance of copper-based brake materials and analyzed the influence mechanisms.Experimental ProceduresThe copper-based brake materials were prepared by the powder metallurgy method. The composition of the brake materials is shown in Table 1. Fe and SiO₂ were added to the brake materials in different proportions by weight, and the samples were sintered in a low oxygen atmosphere at 850 ℃ for 2 hours.Table 1. Composition of copper-based brake materials (wt.%)Material Cu Fe SiO₂ A base 100 - - B 99.5 0.5 - C 99.0 1.0 - D 98.5 1.5 - E 99.0 - 1.0 F 98.5 - 1.5 The friction and wear tests were carried out using a pin-on-disk (POD) tester under dry sliding conditions. The test parameters were set as follows: the sliding distance was 3000 m, the sliding speed was 3.3 m/s, and the applied load was 40 N. The friction coefficient and wear rate were recorded during the tests.The microstructure and phase composition of the brake materials were observed by scanning electron microscopy (SEM) and XRD analysis, respectively. The hardness of the materials was measured using a Vickers hardness tester.Results and DiscussionFriction and wear performanceThe friction coefficient and wear rate of the brake materials with Fe and SiO₂ additives are shown in Figure 1. It can be seen that the friction coefficient and wear rate decreased with the increase of Fe and SiO₂ content. The samples containing 1.5 wt.% Fe or 1.0 wt.% SiO₂ had the lowest friction coefficient and wear rate, which were 0.17 and 2.48 × 10⁻⁷ mm³/N·m, respectively.Microstructure and phase compositionThe SEM images of the brake materials are shown in Figure 2. It can be observed that the surface of the samples with Fe and SiO₂ additives was smoother and more uniform than that of the base sample. The surface was covered by a thin layer of Fe and SiO₂ particles, which could reduce the abrasive wear and adhesion wear of the brake materials.The XRD patterns of the brake materials are shown in Figure 3. The diffraction peaks of pure Cu, Fe, and SiO₂ were observed in the patterns of the mixed materials. The Fe-SiO₂ layer was formed on the surface of the brake materials, which had a high hardness and a low plastic deformation under high-temperature and high-load conditions.HardnessThe Vickers hardness of the brake materials is shown in Figure 4. It can be seen that the hardness increased with the addition of Fe and SiO₂. The samples containing 1.5 wt.% Fe or 1.0 wt.% SiO₂ had the highest hardness, which were 277 and 261 HV, respectively.MechanismThe addition of Fe and SiO₂ could form an Fe-SiO₂ layer on the surface of the brake materials, which could effectively reduce the friction coefficient and wear rate. The Fe-SiO₂ layer had a high hardness and a low plastic deformation under high-temperature and high-load conditions, which could reduce the abrasive wear and adhesion wear of the brake materials. The Fe-SiO₂ layer could also absorb the metal ions and reduce the oxidation reaction between the brake materials and the air, which could improve the therma。