Comparison Between Nano- and Micro-Sized Copper Particles as Fillers in NAO Friction Materials

In this study, the comparative role of nano- and micro-sized Cu powder in exploring the influence on the tribo-performance of friction materials in the form of brake-pads is discussed. Two friction composites were developed by keeping allthe ingredients constant and varying the size of the selected filler (copper powder). The developed micro-composite contained 10% (wt) Cu (400 - 600 mu m) while in the nano-composite only a part (2%) of the micro-powder was replaced by a nano-powder (50 - 200 nm) since 10% replacement was not possible because of the agglomeration problem. One more composite without any metallic filler was also developed for the sake of comparison. For tribo-evaluation, the brake-dynamometer testing was selected. The performance properties, such as friction, wear and sensitivity of friction towards load, speed and temperature were studied as per industrial practice. It was concluded that the inclusion of nano-Cu powder (just 2%) improved the performance properties significantly. Micro-composite was a moderate performer while composite without Cu powder proved the poorest. The quality of a tribo-layer transferred to the disc as studied in SEM was confirmed to be one of the reasons for the improved performance of the nano-composite.