Experimental Investigation on the Tribo-Thermal Properties of Brake Friction Materials Containing Various Forms of Graphite: A Comparative Study

The objective of this research work is to study the impact of graphite forms used as solid lubricant additives on brake friction materials performance. Three composites were fabricated using the conventional process and were characterised for its physical, chemical, mechanical and thermal properties conforming to industrial standards. The thermal stability of the graphite particles and developed composites was measured in an air atmosphere using the thermogravimetric analyser. The tribological performances were studied using the Chase friction test machine as per IS-2742 Part-4 standard. The results indicated that the friction composite containing expandable graphite exhibited better thermal stability with good fade and recovery performances. This led to enhance wear resistance and stable friction due to its better heat dissipation and lubricity comparing with the other two composites. An empirical relationship for the friction and wear was developed based on Chase test results. The worn surface morphologies of the Chase tested composites were analysed using scanning electron microscopy to study the sensitivity of the friction–wear mechanisms to the graphite-type effect.