Microstructure and wear mechanisms investigation on the brake pad

The current study is carried out to understand the various wear mechanisms of the friction materials and improve their wear and frictional properties. The investigation has been conducted on three types of brake pads; a real automotive pad and two other composite formulations. One of the formulated composites comprises graphite lubricant. The Pads are subjected to; surface analysis using EDXS, SEM, and mapping investigations before and after the wear test, to evaluate the surface properties. The results demonstrate better wear and friction properties for the formulated material comprising the lubricant. The surface investigations exhibit abraded phases from the real pad after service. The wear modes in the real pad are; physical and chemical reactions in the form of corrosive layers and metallic oxides, deep cracked surface due to the thermal fatigue, abrasive wear, and glazed surface. On the other hand, the abrasive and fragmental wear, and fatigue cracks are the wear modes in the graphite-free formulated sample, while a glazed surface is the dominant wear mode in the material containing graphite. A high diffusion of the graphite lubricant on the pad surface after friction actions has been proved. As a result, a protective film formed on the surface, leading to reduce the aggressive friction between the mating surfaces and enhances the adhesion forces between the hard particle and the composite mixture, keeping them embedded inside. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The study investigated wear mechanisms of different brake pads, finding that compounds with graphite lubricant exhibit better wear and friction properties. Real brake pads showed abrasive phases and corrosive layers, while graphite-free samples had abrasive and fatigue-related wear, and those with graphite had glazed surfaces as the dominant wear mode. The diffusion of graphite lubricant on the pad surface formed a protective film, reducing aggressive friction and enhancing adhesion forces.