Effect Of Graphite Replacement With Ti₃SiC₂on The Properties Of Copper Matrix Friction Materials

In recent years, the development of high-speed trains has yielded significantachievements. The high-speed train in China, for example, has reached a record speed of394.3Km/h. As a train speeds up, higher requirements are placed on its brake materials.High-speed trains for effective braking require a high braking energy, the flashpointtemperature near the surface of the brake pad can reach1000°C. Conventionalcopper-based friction materials feature flake graphite as an antifriction phase. However,flake graphite cannot inhibit high temperature oxidation. At very high temperatures,graphite oxidation can decrease the drive and increase the wear of the brake pads,seriously impacting the safety of the train. Ti₃SiC₂is a ternary-layered compound withceramic and metal performance. Its thermal conductivity and hardness are better thanthose of graphite; more importantly, the material has good thermal shock resistance andhigh-temperature oxidation resistance. Replacing graphite with Ti₃SiC₂thus has promisingapplication prospects in high temperature friction conditions.In this paper, Ti₃SiC₂bulk materials was fabricated by using spark plasma sintering（SPS） method. Then those bulk materials were crushed into particles by vibrating grindingmill. Make Cu powder mixed with Ti₃SiC₂particles, then use spark plasma sinteringpreparation for Cu-Ti₃SiC₂composite material, testing its physical properties andmechanical properties. And with Ti₃SiC₂as a lubricating component added to thecopper-based friction materials, studied Ti₃SiC₂particles on the properties of copper-basedfriction materials. Explored the friction and wear behavior and mechanism of frictionmaterial at different friction conditions,the results shows that:（1） Ti₃SiC₂and Cu experience bidirectional diffusion at high temperatures （e.g.,900°C）.Cu atoms run into the lattice of Ti₃SiC₂and destroy the crystal structure of Ti-Si bonds. Siatoms enter the Cu crystal lattice, forming Cu（Si） solid solution, remaining stable Ti-Coctahedral at Ti₃SiC₂interface.（2） Choose Cu as a substrate, use Ni, Fe etc. reinforce the matrix, SiO2as the frictioncomponent, Ti₃SiC₂partial substitution of G as the lubricant at900°C for sintering temperature obtain a friction material. Under a high speed friction access to a stablefriction coefficient, the friction coefficient maintained at about0.3.（3） During the friction, Ti₃SiC₂particles and the substrate have a solid combination, withno break off. After high temperature friction, there form a complete lubricant film on thefriction surface of the friction layer, which is comprised of SiO2, TiO via componentdetecting. There exhibit a superior high-temperature oxidation resistence for the flakegraphite.