Towards a better understanding of the structures existing on the surface of brake pads

In the present investigation, optical microscopy, confocal laser scanning microscopy (CLSM), microindentation and image segmentation were employed to investigate the different structures existing on the worn surface of a non asbestos organic (NAO) and a low metallic (LM) brake pad. The following structures were identified on the surfaces of the studied pads: (i) deformable and non-deformable primary plateaus, (ii) secondary contact plateaus formed with and without the support from the structural components of the pad (the primary plateaus), and (iii) the “elastic highlands”. This last structure stays in a high position on the pad's surface topography and responded very flexible to applied loads. Finally, correlation between friction and the structures found on the pads' surfaces is discussed throughout this paper.