A step towards replacing copper in brake-pads by using stainless steel swarf

Multi-functionality of copper (Cu) in friction materials renders its replacement extremely difficult. However, rising ecological concerns and the imminent ban on its usage make it mandatory to look for an efficient substitute. The present paper explores a possibility to replace particulate Cu filler by stainless steel swarf (SSS) in the brake-pads. A series of five realistic multi-ingredient brake-pads containing SSS as a focussed ingredient was developed by increasing its amount from 0 to 20 wt% in the step of 5%. In another set of pads 10% of SSS was replaced by 10 wt% Cu n particulate form keeping all ingredients same to compare the performance of two fillers. These pads were characterized for their physical, mechanical and tribological properties. Tribo-performance using realistic test parameters was evaluated on the brake inertia dynamometer as per JASO C 406 standard. It was observed that with an increase in the amount of SSS, almost all the properties of brakes pads, including wear resistance improved significantly. Nonetheless, Cu-containing pad proved slightly better in recovery ratio and wear performance by 10%, but inferior in the case of fade mu (mu-coefficient of friction) and recovery mu. Worn surface analysis with scanning electron microscope (SEM) confirmed that SSS had poor interfacial adhesion with the matrix which led to a higher wear of SSS filled pads as compared to the Cu filled pads.