Preparation And Properties Of Hybrid Fibers And Modified Bauxite Composite Friction Materials

With the rapid development of modern transportation industries, people put forward higher demands for vehicles in the comfort, stability, safety and so on. Friction materials in the braking system need stable friction and wear properties and good fade resistance in a large range of speed and temperature. The multicomponent composite friction material in this paper is prepared by phenolic resin as binder, carbon fiber and steel fiber as reinforcement, and a new inorganic modified filler was also added. The friction materials with excellent mechanical properties, thermal stability, friction and wear performance are expected.It is very difficult to meet the comprehensive performances of friction materials under various working conditions by a single kind of reinforced fiber, the multi-fiber reinforced friction materials have become a new trend of the research at home and abroad. The properties and structure of the steel fiber and carbon fiber can complement each other, which can form a complex hybrid cross linked network, and small carbon fibers play a role like "dispersion strengthening" in the framework of steel fibers. In this paper, carbon fiber and steel fiber reinforced friction materials are prepared by hot press molding method, and the influence of fiber hybrid ratio on the mechanical properties, friction and wear properties and the surface morphology were studied The results show that the friction material has good friction stability and recovery performance when the carbon fiber and steel fiber content is 6% and 16% respectively, and the impact toughness is obviously enhanced. The appropriate amount of carbon fiber can help to form a stable and complete friction film on the worn surface, and reduce the wear rate.In order to improve the friction coefficient and fade resistance of the material further, this paper introduces the modified bauxite as inorganic filler. The modified bauxite, made through high temperature foaming and modification process, has advantages of light weight, loose and porous, good plasticity, high interfacial bonding strength and high temperature stability. It is showed that adding 4-8 wt.% modified bauxite can be appropriate to reduce the amount of resin, and the bending strength and impact strength of the friction material are still at a high level. The amount of modified bauxite has an obvious effect to improve the friction coefficient and fade resistance performance, but adding too much will aggravate the friction surface wear, and friction stability significantly reduced. The application of modified bauxite in friction materials has a certain engineering significance.The friction performance is greatly influenced by the external environment and working conditions, and the modern friction materials need to remain suitable friction coefficient and low wear rate in various complex conditions. In this paper, we choose the FM-B2 sample which has good comprehensive performance as the research object, and the small scale sample principle is used. MM-1000 ? friction and wear testing machine is used to simulate the actual running state of cars, and the effects of different braking speed and braking pressure on the friction performance are studied. The results indicate that with the increase of braking speed, the friction coefficient decreases while the wear rate increases. The friction coefficient decreases with the increase of the pressure, and the wear debris is easy to aggregate and compacted to form a friction film under high pressure.which improve the friction stability performance.