Can Ti-Based MXenes Serve as Solid Lubricants for Brake Applications? A Tribological Study

Abstract

Developing brake pad friction materials is critical to enhancing the automotive brake system's performance. Solid lubricants play a crucial role in reducing wear and maintaining friction under demanding conditions. While molybdenum disulfide (MoS2) remains widely used, recent progress in 2D materials has opened new possibilities. Among these, titanium-based MXenes (Ti3C2Tx) have emerged as promising candidates due to their mechanical strength, thermal resilience, and inherent self-lubricating properties. This study presents the first comprehensive evaluation of Ti3C2Tx and MoS2 as a solid lubricant in automotive brake pad composites. A fixed matrix composition of steel fibers, barium sulfate, phenol-formaldehyde resin, and iron oxide is maintained across three formulations: a MoS2-based, a Ti3C2Tx-based, and a hybrid combining both additives. The samples are fabricated adopting powder metallurgical techniques. Samples evaluation is conducted to analyze their thermal, mechanical, physical, and tribological properties. Microstructural analyses are performed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Tribological performance is assessed through pin-on-disk against a gray cast iron disk. Results show that Ti3C2Tx-containing composites excel in all aspects compared to MoS2. The hybrid formulation composite reduces specific wear rate by 16.5%, while the Ti3C2Tx-only composite achieves a 48.5% reduction relative to the MoS2 composite.