| Carbon fiber phenolic resin matrix friction materials is called C/F friction materials, which is a new type of friction materials enhanced by carbon fiber and based on phenolic resin adhesive, a grinding agent, antifriction agent,filler and other mixture material with friction function. Due to the excellent performance,it gets more and more popular as a a new research for high quality friction material and widely used in the field of aviation, truck, railway traffic, military and so on. The process of manufacture C/F friction materials includes: the design offiber prefabricated structure, component selection formula, composite curing process optimization. Among this section, the design of carbon fiber prefabricated not only influenced the effect of fiber reinforced, but also make great influence of preparation technology and material property. Currently, in the process of manufacture C/F friction materials, Short cut fiber or 2D carbon cloth is adopted as a reinforcement. While it produces serious defect such as low mechanical strength, easy delamination damage, in the mean time thermo oxidation capability and friction and wear properties has a great raising space. This issue applies 2.5D woven enhancement technique to C/F friction material preparation, in order to overcome the defect of traditional C/F friction material and realize performance enhancements.This research adopts the unit cell modeling and approximate calculation methods, functional relation between weft density Pw and warp density Pj is obtained which is related to the total purity Z of 2.5D prefabricated structure. And design and prepare the deep crossing linking woven(S-1, S-2, S-3)and the curved shallow crossing linking woven(Q-1,Q-2,Q-3) carbon fabrics reinforced phenolic resin friction materials whose carbon fabrics volume fraction is 30%,40% and 50% respectively,and researches 6 kinds of the pore size distribution of 2.5D prefabricated structure; And then adopts the optimal composite molding process to the preparation of three kinds of the deep crossing linking(SM-1,SM-2,SM-3) and (QM-1, QM-2, QM-3) prefabricated structure reinforced C/F friction material.In the mean time the preparation of the carbon fiber volume fraction were respectively 30%,40% and 50% chopped fiber reinforced C/F friction material(DM-1,DM-2,DM-3) for controlled trials. Researched the bending performance, shear properties,Oxidation properties, friction and wear performance of different C/F friction materials to get the response mechanism of the behavior under different test conditions, at last analyzed the prefabricated structure and the influence that carbon fiber content to the different properties of C/F friction materials systematically. The concluding is as follows:(1) In the same conditions, the average pore diameter, maximum aperture, smallest aperture, maximum distribution aperture of the deep crossing linking woven carbon fabrics prefabricated were greater than the curved shallow crossing linking prefabricated structure, the porosity and density of QM was greater than SM. With the increase of the carbon fiber content, the average pore diameter, maximum aperture, smallest aperture, maximum distribution aperture of the fabrics prefabricated decreased, the density of SM increased, the opening porosity increased at first then decreased, the density and opening porosity QM all decreased; the density of DM increased gradually while the change of opening porosity was probabilistic. The opening porosity of 2.5D woven fabric prefabricated reinforced C/F friction materials is under 7.5% and its density isabove1.45g/cm3, which indicated this material was full of good density.(2) The bridge doweling and intervalarrest propagating cracks function of 2.5Dwoven fabric prefabrication carbon fiber and the substrate mixture made the C/F friction material keeping maintain structural integrity even under the condition of matrix component damage, showing outstanding mechanical properties. The bending strength of 2.5D woven fabric prefabricated reinforced C/F friction materials was greater than chopped fiber reinforced C/F friction material; when the fiber content was small, the bending strength of QM was greater than SM; when the fiber content was bigger, the bending strength of QM was less than SM.With the increase of fiber content, the bending strength and elasticity modulus of2.5D woven fabric prefabricated reinforced C/F friction materials all increased at first then decreased. The bending strength of DM increased gradually and the elasticity modulus of DM decreased at first then increased. The shear strength of different C/F friction material was characterized as SM>QM>DM; With the increase of fiber content, the shear strength and elasticity modulus of C/F friction materials were characterized as increased at first then decreased.(3) In the some carbon fiber volume fraction, different C/F friction material oxidizing of carbon fiber reinforcement has different performance. The cyclic oxidation loss rates were characterized as:QM<SM<DM,2.5 D precast reinforced C/F friction materials of thermal oxidation performance was superior to the short cut fiber reinforced C/F friction material; With the increase of carbon fiber content,substrate mixture decreased, polymer reduced, oxidation loss became lower, material performance of thermal conductivity increased and oxidation damage rate became also lower.(4) In other conditions of the same case, the relations of friction coefficient between C/F friction material was characterized as:DM> QM> SM; Friction surface deeply characterized as:DM>QM>SM,2.5D woven fabric prefabricated structure reinforced C/F friction material had a smooth process of friction and low wear rate. With the increase of carbon fiber content, the friction coefficient of C/F friction materials increased with the decrease of the first; And wear increased with the decrease of after the first, to some extent increasing carbon fiber content was helpful to reducing the wear rate. |
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