Design And Fabrication Of Copper-base Powder Metallurgy Friction Material For Braking Of High Speed Train

On June 26,2017,the official opening of the“Fuxing”EMU with a speed of350km/h marks the high-speed train independently developed by China to reach the world's advanced level.With the increase of train running speed,the problem of train braking safety has drawn increasing attention.As the core component of high-speed train braking system,the friction performance directly affects the safety and stability of train braking performance.Therefore,it is important to improve the reliability and stability of the train braking system.Based on the basic physical properties and chemical composition of high-speed railway brake pad friction materials,this paper designs and prepares copper-based friction materials for high-speed railway brakes,and tests their physical properties,microstructure,chemical composition and friction performance.The main research and achievements of this article are as follows:1.Analyze the brake pad material currently being used in China's CRH380A high-speed train,and find that the density of the brake material is?₀=4.82g/cm3,shear strength is 22.7MPa,Brinell hardness is 66.2MPa,and the friction material contain copper powder,iron powder,chromium powder,chromium iron powder,molybdenum disulfide,graphite,silica and alumina powders.2.Designed the basic formulation,external dimensions of the copper-based powder metallurgy friction material,the pretreatment scheme of the formulation raw materials,the mixing process,the cold-pressing forming process parameters and the high-temperature sintering process curve,determined the specific processing parameters,and use the designed plan to prepare the#1 sample for the basic formula,and the performance of the sample is tested and analyzed..3.Based on the basic formulation,improved the matrix elements,friction elements,lubrication elements.and#2,#3 and#4 samples are made.The physical properties,friction test,microstructure,and chemical composition of all samples are also examined.The experimental results show that:#2,#3,and#4 samples are all more stable than those of#1 samples;the Sn element improved the#2 sample of the matrix component with a relatively stable coefficient of friction,high hardness,and density.The overall performance is also good;the friction coefficient of the#3 sample of the vanadium-iron modified friction element is the highest;the porosity of the#4 sample of the small-grain graphite improvement lubrication element is higher,and the graphite junction region is more dispersed;The detected elemental content all meet the elemental requirements in the"Temporary Technical Conditions for EMU Brake Pads",and achieve the purpose of improvement.The detected elemental content are all meets the requirements of“Temporary Technical Specifications for EMU Brake Pads”and achieve the purpose of improving the#1 sample.