Influence of a Novel Hardener p-toluene Sulfonic Acid on Mechanical and Wear Response of Phenolic-Based Friction Materials

The current work aimed to determine the effect of p-toluene sulfonic acid (PTSA) in phenolic-based friction materials on mechanical and tribological properties. This study involved the use of phenolic resin as the binder, PTSA as the hardener, treated coconut coir whiskers as the reinforcing fiber, graphite particulates as dry lubricant, and granite fines as fillers. Synthesis was carried out by hot and cold setting techniques. In addition to hot set linings (HSLs) and cold set linings (CSLs), a lining without PTSA was fabricated for comparison. To analyze the mechanical response of the different compositions, tensile tests, compression tests, micro-Vicker's hardness tests, and density measurements were performed. Evaluation of the friction coefficients along with the wear rate was carried out using two-body sliding wear tests. The wear tests were carried out at loads of 5–15 N and speeds of 400–600 rpm. CSLs showed a coefficient of friction of 0.29 and average wear rate of 2.67 × 10⁻⁶ mm³/Nm and HSLs showed a coefficient of friction of 0.48 and average wear rate of 2.24 × 10⁻⁶ mm³/Nm. Optical microscopy and scanning electron microscopy (SEM) were used to study the microstructure of the friction linings and the wear morphology of the different linings was analyzed by SEM along with energy-dispersive spectroscopy (EDS) analysis.