Comparative performance of barium sulphate and cement by-pass dust on tribological properties of automotive brake friction composites

Automotive brake friction composites based on several combinations of barium sulphate and cement by-pass dust (CBPD) were manufactured and tribo behaviour is examined as per European regulations on a Krauss machine. The friction coefficient increased upon increasing the amount of CBPD from 0 to 30 wt% and then decreased above 30 wt% CBPD and below 20 wt% barium sulphate contents. Conversely, friction fluctuations and wear increased with decreasing barium sulphate and increasing CBPD contents. In particular, 20 wt% barium sulphate and 30 wt% CBPD filled composites showed the highest friction performance of 0.361, moderate friction stability of 0.76, highest recovery performance of 123.27%, and lowest friction variability of 0.60, whereas the composite with 50 wt% CBPD showed the highest fade resistance of 15.36%. The friction and wear analysis revealed that the fade and recovery response decide the overall frictional performance, whereas material integrity and fade response were the significant determinants of wear performance. The composites' worn surfaces were examined to investigate the associated wear mechanism at the braking interface.