Synergistic effect of tungsten disulfide and cenosphere combination on braking performance of composite friction materials

• Developed new class of brake composites based on WS2 and cenosphere.
• Synergistic effect of WS2 and cenosphere for enhanced friction stability.
• Wear surface morphology revealed composition specific topography.
• Friction fade-recovery performance remained optimal.

Tungsten disulfide (WS2/TDS) based cenosphere (Cn) filled friction composites with varying cenosphere to WS2 ratio (Cn/TDS) were fabricated by compression molding of phenolic resin based dry formulation mix and evaluated for their thermal, thermo-mechanical and tribological performances. The loss and revival of braking friction effectiveness due to heating or cooling of the disc termed as fade and recovery performance have been characterized on a Krauss friction testing machine following ECE R-90 industrial standards. The fade performance remained dependent on Cn/TDS, where enhanced fading could be correlated to lower Cn/TDS value accompanied with broader frictional fluctuations i.e. μmax–μmin. A decrease in the frictional-recovery response ensued with increase in Cn/TDS. Dynamic mechanical analysis revealed an increase in storage modulus till 2.5 wt.% of TDS loading followed by consistent decrease whereas two distinct peaks in loss modulus plots that are composition independent have been observed. Scanning electron microscopy revealed the worn surface morphology associated with the dynamics of contact patches formation and deformation vis-a-vis friction layer formation as integrally responsible for the observed friction performance. Energy dispersive analysis of X-rays (EDX) enabled compositional analysis of the friction layer viz. Fe, W, Si, and Al content which may have a mechanistic role in controlling phenomena like, disc rubbing, lubricity, porosity, and hardness of friction layer formed during braking application.

showing correlation between enhanced frictional stability and enhanced visc-oelastic energy dissipation.Figure optionsDownload as PowerPoint slide