Thermal and Fade Aspects of a Non Asbestos Semi Metallic Disc Brake Pad Formulation with Two Different Resins

Abstract

The formulation of a brake pad requires the optimization of multiple performance criteria. To achieve a stable and adequate friction (µ), the brake pad materials should have low fade and higher recovery characteristics coupled with less wear and noise. Among the properties mentioned, resistance to fade is very difficult to achieve. The type and amount of resin in the friction material is very critical for structural integrity of the composites. The binder should not deteriorate under any diverse conditions. The thermal stability of friction materials and its capacity to bind its ingredients collectively under diverse conditions depend upon the quality and proportion of resin. The current work evaluates the fade and recovery behaviour of developed friction composites from two different resins which are traditional straight phenolic resin and the alkyl benzene modified phenolic resin. Two brake pads with these different resins were fabricated as per Industrial Standard. TGA is carried between 150 – 4000 C as this zone of temperature is very critical which accounts for the weight loss (Thermal degradation). Friction and wear studies were carried out on a friction coefficient test rig as per SAE J661a standard. The results showed that the fade and wear of the friction materials were closely related to the thermal decomposition of the binder resin and durability of the contact plateaus, which were produced by the compaction of wear debris around hard ingredients on the rubbing surface. It was clearly observed that the friction materials with modified resin showed significant reduction in fade %. Friction materials made with higher thermal stability showed resistance to fade. However wear didn’t show much noticeable changes.