A study of brake contact pairs under different friction conditions with respect to characteristics of brake pad surfaces

In the present study, influences of friction conditions on friction and wear behaviors, as well as characteristics of brake pad surfaces were investigated. Low metallic (LM), semi metallic (SM) and non-asbestos organic (NAO) brake pads sliding against an iron disc were tested using a pin-on-disc tribometer. Results show that the friction coefficient and specific wear rate decrease with increasing contact pressure and sliding velocity. For the morphology of brake pad surface, friction layers are large with few cracks on surfaces of SM and LM brake pads. While for NAO brake pad, friction layers have a comparatively slender and irregular shape. From fractal analysis, the fractal dimension of brake pad surface is in the range of 2.38–2.84 for all brake pads.