Study On The Friction And Wear Properties Of Rare Earth Lanthanum Oxide Reinforced Resin Based Automotive Friction Plates

Resin based friction materials are widely used in automobile industry because of their high mechanical strength,large modulus of elasticity,wear resistance and stable friction coefficient.However,the harsh working conditions put forward higher requirements for the comprehensive performance of resin based friction plates.In the resin based friction materials,the lack of active groups on the surface of metal reinforced fibers leads to poor interface performance between resin binder and metal fibers,which becomes the weakest link of automobile friction plates.In addition,the fillers can adjust the friction coefficient,reduce the wear rate and improve the strength of the matrix.How to improve the interface adhesion between the binder and the reinforced fibers,and how to optimize the fillers formula,so as to obtain the automobile friction plate with excellent performance and long service life,have become an urgent problem to be solved.Rare earth elements are located in the third group of the periodic table.They have unique 4f electronic layer structure and high chemical activity.They are generally in the form of rare earth compounds.Their interface bonding is excellent.Therefore,they are widely used in material surface modification,lubrication,and heat resistance improvement.Lanthanum oxide has a hexagonal structure,which has a good anti-wear effect.The addition of lanthanum can establish an intermediate at the interface between resin and metal fiber,so as to improve the interface bonding performance.In addition,nano silicon carbide and nano boron carbide have high hardness,specific stiffness and specific strength,and wear resistance.They are used to transfer and distribute external loads in particle reinforced friction materials to improve the strength of friction materials.Based on the characteristics of lanthanum oxide,nano silicon carbide and nano boron carbide,this paper studies the properties and wear mechanism of lanthanum oxide reinforced automobile friction plate,and explores the friction mechanism of nano silicon carbide and boron carbide composite lanthanum oxide reinforced automobile friction plates.The temperature and stress distribution in the process of friction and braking of automobile friction plate are summarized by using the thermal structure coupling analysis model.The research contents and specific work are as follows:(1)The effect of rare earth lanthanum oxide on the friction and wear properties of resin based automotive friction discs was studied.The mixture of lanthanum oxide with copper fiber,barium sulfate whisker,copper powder,magnesium oxide,alumina,zirconium borate,calcium silicate,chromite powder,aramid fiber,NBR and graphite was used to enhance the properties of lanthanum oxide.The results show that when the lanthanum oxide content is 6%,the shear strength and hardness of the friction sample are the highest,the high temperature friction coefficient is high,the wear is low and stable,the wear surface is smooth,flat,the damage is the smallest,and the wear mark is the shallowest.Friction materials show different wear mechanisms in the range of lanthanum oxide content.At low content(<6%),abrasive wear and adhesive wear are dominant,at high content(>6%),adhesive wear and fatigue wear are dominant.(2)The effect of nano filler composite lanthanum oxide on the friction and wear properties of automobile friction plate was studied.CaSiO3,nano SiC and nano B4C Composite lanthanum oxide reinforced automobile friction plates were prepared,and the friction and wear experiments were carried out on the friction samples.The high-temperature friction coefficient of nano SiC packing sample is obviously improved,the wear rate is larger,and the wear surface has more wear marks;the friction coefficient of nano B4C packing sample is lower,the friction coefficient is stable,the wear rate is low,and the wear surface is smooth and smooth.The nano B4C particles with high hardness strengthen the mechanical engagement force of the material and improve the friction and wear properties.The wear mechanism of friction materials with nano silicon carbide is mainly abrasive wear,and that with nano boron carbide is mainly fatigue wear.(3)The distribution of temperature and stress in the braking process of automobile friction plate is studied.The thermal structure coupling analysis method is used to analyze the friction heat generation process of the brake,and the thermal structure coupling analysis model of the disc brake is established.First,the dynamic calculation of the braking process is carried out,and then the solid 226 coupling element with temperature freedom is introduced to calculate the coupling dynamic model.The simulation results show that the temperature in the center of the friction plate is 498.57? and the stress is 18.929 MPa.The maximum stress and the maximum temperature appear at the same time and in the same position,and the distribution of temperature and stress presents a certain gradient.There is a coupling relationship between the temperature and stress of automobile friction plates.