Susceptibility of eco-friendly brake-pads to noise-vibration emanation due to siloxane treatment on alumina particles

Abstract

In case of friction materials (FMs), contribution towards desired friction level and counter-face rejuvenation during braking is manipulated by adding abrasives such alumina, silica, zirconia, SiC etc. in adequate level. However, such particles have less adhesion with the resin and hence are easily dug out during braking contributing to the higher wear and to propensity to the noise-vibration. If efforts are made to enhance the filler-matrix adhesion, not only the wear of FMs would reduce, the friction performance would also improve. This is due to the fact that they will stay for a longer time on the tribo-surface of the FM to contribute fully towards controlling the µ and avoiding three-body abrasion phenomena to the extent possible. Finally, this is expected to enhance the noise-vibration (NV) performance of the brake-pads. The first part of the hypothesis has been validated in the authors’ laboratory by including siloxane-treated alumina particles in brake-pads. However, the second aspect (influence on NV performance) that was not considered in the earlier work is addressed in the current paper.Two types of NAO Cu-free brake-pads were developed keeping all the parent formulation identical using alumina (2 wt%) as a theme ingredient (siloxane treated and untreated). An additional type of a brake-pad without abrasive particles was also developed to analyse the effect of abrasive particles on the NV performance. The present study focusses on a detailed experimental investigation for the evaluation of NV performance based on the noise and vibration data obtained from an NV test-rig according to SAE J2521 standard. It was observed that siloxane treatment influenced the NV performance of brake-pads in a beneficial way and an average reduction of 2–3 dB(A) in the overall sound pressure level (SPL) was observed.