Research On The Properties Of Phenolic Resin-base Friction Material Reinforced By Hybrid Fibers

With the development of modern industry,the automobile industry has developed at a high speed.Friction materials play an important role in daily life and are widely used in the braking system and clutch of automobiles and high-speed trains.Vehicle braking performance depends on the comprehensive performance of friction materials,friction materials not only require good wear resistance,stable friction coefficient and excellent mechanical and physical properties,but also have the advantages of light,no pollution,low noise and inexpensive.In order to meet the needs of the automobile industry,a variety of fibers mixed together to strengthen phenolic resin based friction materials have become a hot research topic.In this paper,carbon fiber,steel fiber,composite mineral fiber and polyacrylonitrile fiber were used as reinforcing fibers to prepare phenolic resin-based friction materials.The mechanical and physical properties of friction materials were tested with HR-150 A rockwell hardness tester and XL101 shear tester,and the friction and wear properties of friction materials were tested with XL112 constant speed friction tester.Range analysis method and S-3700 N scanning electron microscope were used to research the influence of hybrid fiber on the comprehensive properties of resin-based friction materials,and the reasonable proportion of reinforced fiber was determined.By the golden section method to optimize the content ratio of reinforcing fiber and orthogonal experiment design,the optimized formula through the fuzzy comprehensive evaluation and screen the optimal formula,and analysis unworn and worn friction material,cross section,microstructure of worn debris,and combined with the worn surface energy spectrum analysis of element content,after study the enhancement mechanism.Results show that the carbon fiber on friction and wear properties of phenolic resin matrix friction materials,in the high temperature friction process,the change of internal crystal structure,the friction surface layer to form a layer of dense transfer film,the friction contact surface play a protective effect,this surface is helpful to slow the recession phenomenon of friction materials;The content of steel fiber has great influence on the hardness of resin base friction material.Composite mineral fiber has a great effect on the wear rate of resin-based friction materials.The content of polyacrylonitrile fiber has a great influence on the shear strength of resin-based friction materials.The change of hybrid fiber level can change the pore size and microstructure of materials and components of reunion phenomenon,thus affecting the mechanical and physical properties of the material and friction and wear performance,when the fiber content is 22.5%(carbon fiber 4.8 wt.%,steel fiber 13.2 wt.%,composite mineral fibre 3.7 wt.%,polyacrylonitrile fiber 0.8 wt.%),phenolic resin matrix friction materials have the highest comprehensive economic and technological value,S3 samples for optimal formula in this paper.The different content of hybrid fiber and the effect of the binder modified phenolic resin base and nitrile rubber powder on the enhancement mechanism of the friction material can change the pore size,microstructure and agglomeration of the raw material components,thus affecting the mechanical and physical properties and friction and wear properties of the material.