Preparation And Study On Carbon Nannotubes Modified Carbon Fiber Reinforced Paper-based Friction Material

In recent years, the study of friction material has been obtained rapidgrowth with the development of automotive and aviation industry. Paper-basedfriction materials are mainly used in automotive driveline clutches which workedin lubricating medium. At present, it is still a great challenge that how to improvethe friction coefficient, friction stability, heat resistance and the wear resistanceof paper-based friction material. Therefore, many scholars researched higherperformance of paper-based friction material via two routs; one is improvementof interface bonding between fibers and resin; another one is finding out the fitfiller system to improve the properties of the materials.Firstly, the paper-based friction material, which possess fine interfacialbonding between fibers and phenolic resin, was prepared by adding the bamboofiber and carbon nanotubes into the materials. It is found that carbon nanotubescan effectively improve the friction properties and the combinding capacitybetween fibers and resin of the material. When the carbon nanotubes contentsreached4wt.%, the dynamic friction coefficient of the material is0.1031, andthe sample has good friction stability and wear resistance. Thermal analysisresults showed that the mass loss of the sample with4wt.%carbon nanotubesreduced10%compared to that of sample without carbon nanotubes when thesamples were heated to1000℃.The SEM results showed that, bamboo fiber caneasily attach to the carbon fiber, and carbon nanotubes are easily adsorbed on thesurface of bamboo fiber, which could protect the thermal decomposition of thebamboo fiber during the friction progress and improve the heat resistance of thesample. To further improve the friction properties of the paper-based frictionmaterial, silicon carbide, boron carbide, alumina, zirconium oxide, zirconiumboride, and compound of rare earth were added into the above system,respectively. It is discussed the friction properties and the relationship betweenfiller contents and friction properties of the samples. Results present that whenthe sample contains3wt.%Ce(NO3)3and15wt.%Zirconium boride, the frictionmaterial has the best friction performance, the dynamic friction coefficient of thesample was0.13285, the ratio of the static to dynamic friction coefficient was0.9010, the variation of the dynamic friction coefficient of the sample during500times friction tests was0.75, at then the wear rate of the sample was0.6×10-8cm3J-1.Finally, the compressibility and recovery, thermal properties, heat resistanceand dynamic mechanical analysis of the specimens with different zirconiumboride contents were discussed. Results display that with the increase of thezirconium diboride, the compressibility and thermal conductivity of the sampledecreased slightly. However, the dynamic mechanical test and thermal analysisshowed that the specimen with15wt.%zirconium diboride has a high storagemodulus and good heat resistance. Through studying the relationship betweenthe components, the storage modulus, heat resistance and the friction propertiesof the materials, it can be found that the storage modulus and heat resistance ofthe specimen play an important role in the friction properties of the specimen.The specimen has good braking stability when it has great storage modulus, andit has high friction stability and low wear rate when the specimen has good heatresistance.