Development of eco-friendly brake friction materials reinforced with a mechanically alloyed triple-boron system: microstructural insights and tribological evaluation under high-temperature performance

This study introduces the development of sustainable brake friction composites reinforced with a novel triple-boron system, including mechanically alloyed boron oxide, borax, and colemanite. Friction specimens were produced with varying boron mass ratios (3%, 6%, and 9%) and tested against a commercial sample. Pin-on-disc tests were conducted under a constant load (645.16 N) at three sliding speeds (6.7, 9.7, 12.8 m/s) and temperatures (250 °C, 300 °C, 350 °C). The results revealed that the 3% triple boron mechanical alloy (BMA3)-reinforced specimen exhibited superior tribological performance, maintaining stable friction and reduced specific wear rate. Optical analysis confirmed improved surface resistance, plateau formation, and reduced crack propagation. The optimal performance of BMA3 is attributed to a well-balanced tribo-film stability and enhanced interfacial bonding among boron compounds, which collectively suppress crack initiation and stabilize the wear mechanism. The synergistic interaction between lubricating boron oxide, fluxing borax, and rigid colemanite fosters a durable transfer film, leading to the observed low wear and consistent friction behavior. These findings suggest that locally sourced, mechanically alloyed boron systems offer an environmentally friendly, high-performance alternative to conventional brake materials.