| The resin based friction material has stable friction coefficient,good wear resistance,low noise and low price.It is the most widely used friction material in automobile braking system and transmission system.Resin based friction materials commonly used in lubricants mainly include natural graphite,synthetic graphite,calcined petroleum coke and other carbon fillers and metal sulfide.The h-BN and graphite have the same crystal structure and similar lattice constants,and their properties are clean and high temperature resistance.In this paper,h-BN was used as lubricating material in resin based friction material,It is used to improve the cleanliness and high temperature resistance.In this paper,h-BN/PF resin friction materials were prepared.Characterized the thermodynamic properties,tribological properties,wear properties and noise properties by the TGA,CHASE tester,Krauss tester,LINK dynamometer test machine.The tribological properties of different processes and combinations on ftiction and wear and noise performance were studied.The preparation process of h-BN doped resin based friction material and the combination with other materials were optimized.The preparation process of the h-BN/PF resin friction materials are mainly affected by the molding temperature,pressure and time.The best preparation process as follows:the best molding temperature is 160?,the best molding pressure is 500kg/cm2,and the best forming time is 300s.Under this process,the friction material is not only guaranteed to cure completely,but also has good tribological,wear and noise performance.The physical properties of the resin matrix friction material products were improved by the h-BN.It can reduce the density and hardness of products,improve the room temperature compression and high temperature compression.Compared with the synthetic graphite and natural graphite,the h-BN has the similar anti friction,wear resistance and noise reduction performance.However,it has the different friction properties with graphite.The tribological reduction effect of graphite at room temperature is prominent.However,the tribological reduction effect of boron nitride at high is temperature remarkable.The reduction of the coefficient of room temperature and high temperature are 1.98%and 4.05%,respectively;and the reduction of wear at the room temperature and high temperature are 18.92%and 43.22%respectively;and the noise is reduced by 56.12%.The h-BN combination with synthetic graphite,natural graphite and potassium titanate all showed better tribological properties.Compared with the single synthetic graphite,the combination of the h-BN and synthetic graphite can improve the braking stability by 19.35%,the wear resistance is improved by 11.80%and the noise reduction by 27.95%.Compared with the single natural graphite,the combination of h-BN and natural graphite can improve braking stability by 19.66%,the wear resistance was increased by 8.28%,and the noise was reduced by 48.13%.The h-BN and potassium titanate whisker combination compared to single h-BN,coefficient of friction is increased by 5.30%,improve the stability coefficient of friction coefficient increased by 24.41%,the wear resistance is increased by 5.15%.In this paper,the mechanism of friction reduction and anti-wear and noise reduction are discussed.The h-BN rule of layered structure,the atomic force between layers is weak than the atomic force inner layer.The atoms are easily sliding along the layer under the tangential friction force,the friction layer and transfer layer are formed around the short fibers and hard particles,thereby reducing the coefficient and wear.Potassium titanate whiskers due to appropriate hardness,modulus,thermal physical properties,the rivet layer is good to the properties,which is good to form friction layer and improve the friction layer continuous.In this paper,the h-BN/PF resin friction materials has the characteristics of low hardness,low density,high compression,excellent friction and wear performance,low noise and so on.It can fully meets the braking performance requirements. |
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