| With the rapid development of the automotive industry,higher requirements are placed on brake friction materials,which are key component materials in automotive braking systems Currently,thermosetting phenolic resins are widely used as binders in non-asbestos non-metallic brake friction materials,which play a decisive role in the mechanical strength and friction wear properties of friction materials.The poor heat resistance of these resins leads to severe thermal degradation of the friction materials[3]as well as higher wear rate and other problems.Poly(ether ether ketone resins as high-performance resins have excellent high-temperature properties,and as the temperature increases Poly(ether ether ketone undergoes physical morphological changes to fill the microcracks generated in the friction material during braking and enhance its overall performance.Therefore,this paper aims to improve the high temperature friction and wear performance of resin-based friction materials,to study the influence mechanism of Poly(ether ether ketone reinforced resin-based friction materials on their high temperature friction and wear performance and its mechanism of action,to lay the theoretical foundation for the development of a new generation of brake friction materials.The main research contents and results of this paper are as follows.(1)Feasibility study of powder hot pressing Poly(ether ether ketone)reinforced brake friction materials.Based on the existing research base of resin-based brake friction materials,the group designed a hot pressing process to prepare resin-based friction materials with different Poly(ether ether ketone)content for the performance requirements of commercial vehicle brake friction materials,and investigated the influence mechanism of Poly(ether ether ketone)content on the physical and mechanical properties of friction materials and friction wear properties.The results showed that 1)the addition of Poly(ether ether ketone)could reduce the wear rate,and the total wear rate was reduced by 21.5%compared with the friction specimens without the addition of Poly(ether ether ketone);2)the friction factor of the friction material with the addition of Poly(ether ether ketone)in the range of 100-200°C was increased by 3.4%at maximum,but the average friction factor of the specimens with the addition of Poly(ether ether ketone)after 250°C was reduced by 3.8%compared with the specimens without the addition of Poly(ether ether ketone).(2)Optimization of granulation process.By means of experimental optimization design,the granulation process parameters for the best granulation effect were explored under the conditions of detailed analysis of the characteristics of each granulation stage,and the best process parameters such as stirrer speed,barrel speed and time were obtained for each stage,and the uniform and dense granules covered with phenolic resin were prepared.(3)Based on the study of the preparation of Poly(ether ether ketone)reinforced friction materials by powder hot pressing method,it was found that the friction factor of the specimens prepared by direct powder mixing with Poly(ether ether ketone)was not as good as that of the control group of F-0 specimens after 250°C.Starting from the curing mechanism of phenolic resin,the problem of decreasing friction factor generated by powder hot pressing was solved by the method of physical isolation of the two types of resin materials through the pelletizing process.The results of the optimization of the parameters of the pelletizing process were used several times to prepare Poly(ether ether ketone)reinforced resin-based brake friction materials using the pelletizing process,and the performance indexes of the specimens were characterized,and the results showed that 1)the specimens prepared using the pelletizing process with Poly(ether ether ketone)of 3 wt.%had the best friction performance with a recession rate of 7.2%,a recovery rate of 101.3%,and a total wear rate of 2.052×10-7cm~3(N-m)-1;2)further comparison revealed that the friction performance index of the specimens prepared by the pelletizing process was better than that of the specimens prepared by the powder hot pressing process under the same Poly(ether ether ketone content.The highest thermal recession resistance and wear resistance of the pelletizing process specimens were improved by 16.7%and 19.4%,respectively;3)the results of microscopic morphological analysis of the wear surface showed[1]that the Poly(ether ether ketone)resin had heat deformation to fill the microcracks at high temperatures,which effectively improved the recession resistance of the friction brake material.(4)Bench test of Poly(ether ether ketone reinforced brake friction material.By JF160B friction material testing machine(CHASE tester)on the granulation process prepared by different Poly(ether ether ketone)content of the friction material specimens for CHASE test,combined with mechanical properties test comprehensive analysis can be obtained when the polyether 3 ether ketone content of 3wt.%friction material has good thermal recession resistance.Further scaled-down bench tests were conducted on the specimens with this content,and the results showed that the friction factors were in the range of 0.327-0.343,with an average friction factor of 0.335,which was relatively stable at high temperatures and achieved excellent friction performance. |
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