This work compares the friction and wear mechanisms data of heavy vehicle brake lining materials from laboratory and field tests. Friction material operating conditions, such as braking pressure, temperature, and speed, were obtained from braking applications of the vehicle. The laboratory tribological evaluation was carried out using pin-on-disc dry sliding tests. The pins were fabricated from the brake lining material and the metallic discs from the gray cast iron drum material. The response surface methodology (RSM) approach using a central composite design was proposed to predict the effects of the contact pressure (P) and sliding velocity (V) on the friction and wear of the brake lining materials. The morphology and chemical composition of the worn surfaces from laboratory and field tests were analyzed with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. The laboratory-scale test results were used to adjust an empirical P.V (pressure × sliding velocity) RSM model that predicts the effect of contact conditions on friction coefficient and volume loss by wear of the brake lining materials. Abrasion grooves were observed on the worn surfaces of the brake lining and drum pair. The hard primary plateaus observed on the brake lining worn surface promoted the drum material transfer and the formation of secondary plateaus from the agglomerated iron oxide. For higher pressure and sliding distance, the transfer of particles from the drum surface to form a compact layer stabilized the friction coefficient. The brake lining material worn surface from the vehicle road tests also exhibits abrasive wear and plateaus formation. In addition, cracks due to contact tensile stress were observed. Laboratory tribometer alloyed identifying the predominant wear mechanisms of brake lining materials. These laboratory-scale tests can be used to predict the tribology behaviour and develop new brake friction materials formulations before evaluating the results from road tests.

Fras-le SA: Mr. Norton Wille, Dr. Michell Felipe, Cano Ordonez, Mr. Francisco Lanferdini Serafini; Universidade de Caxias do Sul: Prof. Dr. María Cristina Moré Farias