The Influence of Adding Copper and Iron Third Body on Brake Disc Temperature

A large number of third bodies are born on the friction surface during braking. Exploring whether the third body has an impact on the friction surface temperature is helpful to recognize the wear factors affecting the brake disc. The effect of the third body composition on the temperature distribution of disc was studied by adding third body method on the TM-I inertial reduced scale brake testing machine, temperature distribution of the disc surface was compared at the pressure of 0.25 MPa and speed of 20–200 km/h under three conditions: no adding third body (NTB), adding Cu third body (CTB), adding Fe third body (FTB). The results indicate that the difference in fluidity and thermal conductivity between CTB and FTB leads to the deviation of the contact state of surface, thus forming the variation of temperature and distribution state of brake disc. At a speed of 120–200 km/h, when adding the CTB, the maximum temperature of disc surface is reduced by 1.9–3.1%, the proportion of the high-temperature zone of radius is reduced by 4.3–13.1%, and the unit width temperature of the radius high-temperature area decreases 2.2–3.2%. When adding the FTB, the maximum temperature of the disc surface rises by 4.1–7.4%, meanwhile, the proportion of the radius high-temperature area and the temperature per unit width of radius are increased by 1.4–5.4% and 5.9–20.2%, respectively. At high speeds, the good fluidity and thermal conductivity of CTB lead to adhesive wear. FTB has high hardness, poor fluidity and thermal conductivity, which causes oxidative fatigue wear.