Comparison of tribology performance, particle emissions and brake squeal noise between Cu-containing and Cu-free brake materials

The present study developed two Cu-free brake materials using carbon fiber or carbon nanotube as the replacements for copper fiber and evaluated their tribology performance, particle emissions and brake squeal noise. Results show that the coefficients of friction (COFs) of the Cu-free brake materials are lower than that of Cu-containing brake material at the braking conditions with low and medium loads. At the high load braking condition, all the braking materials exhibit comparable COFs. Cu-free brake materials present larger specific wear rates than the Cu-containing brake material. However, the application of carbon fiber can reduce the particle number emission. All brake materials exhibit comparable brake squeal noise.