Effect Of Graphite And Paper Forming Methods On The Properties Of Wet Paper-Based Friction Materials

Wet paper-based friction material is a type of friction material used in oil,which is prepared by papermaking method.Its composition and forming method will affect the performance of paper-based friction materials.Graphite is the most widely used antifriction material in paper-based friction materials,but the related research is mainly to explore the role of graphite in sintered metal-based and resin-based friction materials.The forming methods of paper-based friction materials have significant differences with the first two,the structure of the materials is not the same,and the influence of graphite on them also have differences.About the forming method,most of the paper-based friction materials are single layer forming by one time,but this method can not take advantage of each component.So it is necessary to find a suitable forming method to prepare double-layer wet friction materials.But there are few related studies,and there are still some shortcomings in forming methods and develop slowly.Based on the above two aspects,this paper provides a foundation for formulation design and performance optimization of wet paper-based friction materials.In this paper,five kinds of flake graphite with different particle sizes were selected to explore the effect of graphite particle size on properties of paper-based friction materials.The results showed that the graphite with 100 mesh would greatly reduce the porosity of the materials.When the graphite particle size exceeded 325 mesh,the porosity decreased with the decrease of graphite particle size,but the reduction was small.The graphite particle size could affect the thermal conductivity of the materials.When the graphite particle size was 325 mesh and 500 mesh,the thermal conductivity of the materials was better,the thermal conductivity was 0.273w/（m·K）and 0.261 w/（m·K）respectively.When the graphite particle size was 325-600 mesh,the friction coefficient was about 0.137,the wear rate was 8.18-9.08（18）10^-8cm³/J,which was low,and the friction process was also stable.Then three kinds of graphite with different particle sizes were preferred to explore the influence of graphite content on the properties of paper-based friction materials.The results showed that,in order to obtain materials with higher porosity,the content of graphite should not exceed 15%.The thermal conductivity of the materials became higher with the increase of graphite content,but when the content exceeded 20%,the thermal conductivity increased slightly.When adding 15%graphite to materials,the dynamic friction coefficient was 0.139,the torque transmission was stable,and the wear rate was the lowest,which was only 6.3（18）10^-8cm³/J.Considering comprehensively,in paper-based friction materials,the graphite content should not exceed 15%.Finally,a method for forming two-layer paper-based friction materials was optimized,and studied the vacuum resin impregnation system.The performance of four different two-layer paper-based friction materials was studied.The results showed that the comprehensive performance of the double-layer friction material was superior to that of single layer,adding a proper amount of filler,carbon fiber,and aramid pulp to the friction layer could improve the thermal conductivity to 0.572 w/（m·K）,reduce the wear rate to 1.7（18）10^-8cm³/J,and maintain the dynamic friction coefficient stable.