Friction behavior and wear mechanism of brake pads under combined temperature, load, and rotational speed conditions

Brake pads are core friction components in braking systems of high-speed trains, heavy-duty trucks, and polar scientific vehicles. Their tribological performance in extreme environments directly determines braking reliability and safety. The friction behavior and wear mechanisms of brake pad materials under low-temperature dry sliding were experimentally investigated. The coupling effects of temperature (-40 °C, -20 °C, and 25°C), load (30–90 N), and rotational speed (100–200 rpm) on the coefficient of friction and worn-surface evolution were examined using a friction testing platform. SEM, EDS, XRD, and XPS analyses indicate that temperature plays the dominant role in determining the wear mechanism. At -20 °C, the material exhibits quasi-brittle characteristics with wear dominated by fatigue spalling. At -40 °C, complete embrittlement occurs, and wear shifts to brittle fracture. Increasing load aggravates damage but does not alter the dominant mechanism at each temperature. An empirical friction-coefficient model was used as a supporting analysis for the room-temperature dataset, while the low-temperature data were mainly used to discuss the temperature-dependent COF response and wear mechanism. This work clarifies brake pad failure mechanisms under low-temperature dry friction, providing experimental and theoretical support for developing reliable, long-life braking materials in extremely cold environments.