Tribological Effects of Multiwall Carbon Nanotube (MWCNT) on Cu Based Hybrid Composite Brake Friction Material for Medium Duty Automotive Applications

The aim of this work is to investigate the synergistic effect of Multiwall Carbon Nanotube (MWCNT) in a Cu/SiC hybrid composite brake friction material. The brake hybrid composite materials were prepared using copper as a matrix, silicon carbide as a reinforcing fibre, graphite as a solid lubricant and barium sulphate as a filler combined with varying volume percentage (0.0, 0.5, 1.0, 1.5 and 2.0) of Multiwall Carbon Nanotube (MWCNT) by conventional powder metallurgy technique. The prepared brake friction materials are characterized for compression strength, density and hardness to analyze their mechanical properties. The friction and wear behaviour of the composite were carried out using a fully instrumented pin-on-disc (PoD) test rig with linear variable differential transducer for wear rate and strain gauge for friction measurement under dry condition for medium duty applications. The results of this study indicate that the addition of MWCNT in composite brake friction material increases coefficient of friction significantly whereas wear loss of material has shown a decreasing trend with increase in volume percentage of MWCNT. In post-test analysis, the morphology of worn out surfaces, wear mechanisms and compositions of brake friction materials was examined using scanning electron microscope (SEM) with energy dispersive x-ray spectroscopy (EDX). Furthermore, this study also revealed that adhesive wear and delamination mechanisms are predominantly observed on worn-out sample surfaces.