Synergic effect of metallic fillers as heat dissipaters in the tribological performance of a nonasbestos disk brake pad

Abstract

Brake friction linings are made of materials with a highly complex formulation that helps in improving the braking performance. The selection of friction materials with good physical, mechanical, and thermal properties is vital, which will decide the braking performance. Apart from giving good physio-mechanical properties, metallic fillers act as heat dissipaters. The objective of this work is to study the synergetic effect of prominent heat dissipaters, namely copper fibers, brass fibers, and zinc powders. Three simplified formulations were developed with 10, 14, and 18 wt.% of these heat dissipaters and named DB1, DB2, and DB3, respectively. It was observed that the addition of heat dissipaters increased the thermal properties. Tribological properties are tested based on SAE J661 standards. It was observed that DB2 had a consistent and higher coefficient of friction of 0.503 with a higher wear rate (7.6%) while DB3 had adequate μ and lower wear rate. The same batches of brake pads were tested in an inertia brake dynamometer following JASO C406 and a wear test was carried out. It was observed that % fade and % recovery were better for DB2 in both cycles. The wear rate in terms of thickness was lesser for DB2 followed by DB1 and DB3. The wear mechanism was analyzed using a scanning electron microscope. The preference selection index method of optimization was used to evaluate the overall performance parameters of the brake friction composites. Heat dissipaters with 14 wt.% have proved to be the better performers, followed by 10 and 18 wt.%.