Synergistic performance of expanded graphite—mica amalgamation based non-asbestos copper-free brake friction composites

Abstract

Recent advancements in brake pad applications emphasise various friction compositions that exclude toxic components such as asbestos, copper etc., in order to provide superior performance without hurting the environment, human life and aquarium species. In this work, brake friction materials were fabricated by the conventional manufacturing process as standard brake pads using expanded graphite with the synergetic effect of thermal resistant material mica flakes. Six standard brake pads were produced based on varying the expanded graphite by 16, 14, 12, 8, 6 & 4 weight percentage, which is compensated using the Mica flakes by 4, 6, 8, 12, 14 & 16 weight percentage, fixing the composition of other ingredients and designated as BM01, BM02, BM03, BM04, BM05 and BM06. Physical, chemical and mechanical, characterisations of the formed friction materials were carried out in accordance with IS 2742 and ISO 6312. A full-scale inertia brake dynamometer was used to determine the fade, recovery characterisations with the pressure and speed sensitivity as of JASO-C-406. From the experimental observations, BM03 friction composites reveal excellent low fade and high recovery characteristics because of the integrated effect of expanded graphite (superior lubricity) & mica (good thermal stability). Worn surface analysis was studied with the help of a scanning electron microscope. The inclusion of expanded graphite-mica as a hybrid “lubricant-filler” combination in composite materials for friction braking application results in performance synergism.

Evaluation of the effect of the novolac resin ratio on the high temperature performance of the brake pads

“…Tightly pressed samples have a higher density. Higher density and hardness lead to a decrease in porosity [13,25,26]. It is seen that the density increases depending on the novolac resin ratio.…”

“…Actual and visible contact areas differ significantly [8]. The kinetic energy that increases with the increase of friction heat at high speeds degrades the polymeric components and causes a decrease in the friction coefficient [25]. The change in porosity with increasing resin ratio affected the actual contact area of the brake samples.…”

Varying Cu and Zn composition in brass and its effect on the fade and recovery behavior of the phenolic‐based friction composites

“…[6] Since metals have high thermal conductivity, metallic brake pads dissipate more heat to the environment compared to semimetallic and NAO brake pads. [7,8] Heat dissipation is an important factor in the braking phenomenon. The higher the rate of heat dissipation, the better will be the tribological performance of the brake pad.…”

“…[ 6 ] Since metals have high thermal conductivity, metallic brake pads dissipate more heat to the environment compared to semi‐metallic and NAO brake pads. [ 7,8 ]…”

Effect of graphitization percentage on fade and recovery performance of copper-free non-asbestos organic brake pads

“…And also, the quantity of fiber-matrix de-bonding reduced with the growing percentage of graphite. Sathyamoorthy et al (2022b) developed non-asbestos brake pads using various percentages of expandable graphite compensated with mica flake ranging from 4 to 16 Wt.% and analyzed for tribological performance as per JASO-C-406. The combined impact of expandable graphite (better lubricity) and mica (good thermal stability) on friction composites with 12 Wt.% of expandable graphite and 8 Wt.% of mica showed exceptional low fade and high recovery qualities from experimental studies.…”