Eco-Friendly Brake-Pads using Ferritic Stainless-Steel Particles of Varying Sizes: Influence on Performance Properties

Metallic particles in brake-friction materials (FMs) play a vital role in improving mainly strength, friction level, thermal conductivity and hence resistance to fade and during braking operations. Although Copper was the most efficient and popular metallic ingredient in FMs, it is being phased out because of its proven threat to the aquatic life in the form of wear debris. Hardly any successful efforts are reported in open literature barring few on initial exploration of stainless steel swarf (SSS) and particles of stainless steel (SSP) in the authors? laboratory. It is a well known fact that the size and shape of particles affect the performance of FMs apart from their type, concentration etc. In this research, Ferritic stainless steel (SS 434) particles were selected as a theme ingredient in two forms, first particulate (SSP) with two sizes, large (30-45 micron) and small (10-20 micron) and also in the form of swarf. The aim was to investigate the size and shape effect of these ingredients when used to manufacture brake-pads on performance properties including NV (noise and vibration). A series of three multi-ingredient brake-pads was developed comprising SS 434 particles (10-20 and 30-45 micron), SS swarf (Length:1-2 mm, diameter- 50 micron). The developed brake-pads were characterised for physical, mechanical, chemical and thermal properties as per standards. Tribological performance was evaluated on full scale inertia dynamometer by following JASO C406 standards. Brake noise performance was studied on NV rig by following SAE J2521 standards. Results indicated that most of the tribological properties including noise were superior for pads with smaller size SSPs and poorest with swarf (SSS). However, SSS proved best in fade performance. Finally, overall performance was analysed by using ?Multiple Objective Optimizations by Ratio Analysis (MOORA) technique. Morphology of worn brake-pads was studied using a scanning electron microscopy (SEM) and EDAX.