Research On Preparation And Properties Of Cu-based Powder Metallurgy High-speed Train Pad Materials

With the progress of the times,the demands of efficiency,economy and comfort of travel have grown in people's mind.High speed railway has been developed rapidly due to the trend of the times.High speed rail provides a convenient way to travel for people.But,with the increase of speed,the requirement of brake system becomes more and more higher.Whether the high speed train can be stopped safely and stably at a high speed,it has become the core problems which need most concerning.As one of the key components of the friction system,the brake pad material directly affects the safety of the high speed train.Therefore,railway workers and scientific research institutions in the world have done a lot of research works.The development of foreign high-speed rail technology is relatively early,therefore,they have alrea dy very mature master brake material production technology.However,due to the situation of our country,the development is relatively late.And the high-speed train brake plate needs to be imported from abroad.In this paper,the samples of the brake material are perpared by the powder metallurgy technology.In order to test the hardness and density of the material,the MM1000-II friction and wear tester is used to study the friction and wear property of samples.By means of scanning electron microscopy?SEM?,the friction and wear mechanism of the material was analyzed.The results shows that:1.When the ratio of the mass fraction between Al₂O₃ and SiO₂ changes from 2:6to 4:4,the porosity of the brake material decreases with the increase of the content of Al₂O₃.When the mass fraction of the material changes from 4:4 to 8:0,the porosity of the material continues to decrease with the increase of the content of Al₂O₃.But the magnitude of the decrease gradually decreases.The density and hardness of the materials increase with the increase of the ratio of the mass fraction between the Al₂O₃ and SiO₂.2.The friction coefficient of the brake pad material decreases with the increase of the ratio of Al₂O₃ and the wear resistance increases gradually,when the initial braking speed is 2303 r/min.When the initial braking velocity is 5757 r/min,the friction coefficient decreases with the increase of the ratio of Al₂O₃,and the wear resistance increases first and then decreases later.3.The addition of chromium can improve the wear resistance of copper based powder metallurgy brake pads.When the initial braking speed is low?2303r/min?,the increase of Cr content has little effect on the wear resistance of the material.When the content of Cr is between 5% and 15%,the wear of the material decreases with the increase of Cr content.