Raman spectroscopy as an evaluation tool of the wear of graphite lubricants in brake pads

Abstract

Raman spectroscopy is applied for the non‐destructive characterisation of the graphite which is used as solid lubricant in the friction material of semi‐metallic brake pads in vehicles. The characteristics (intensity, position, width) of the main Raman bands assigned to vibrational modes of the graphitic honeycomb structure (G‐band) and to defects (D‐band) are proved useful probes of the quality and wear status of the graphite lubricant because they are sensitive to the structural disorder. It is found that wear of the graphite lubricant proceeds in two stages: transformation of crystalline to nanocrystalline graphite and subsequent amorphisation. Moreover, the intensity of the defect‐related D′ peak is also used in order to obtain information about the nature of the defects.

Use of synthetic Fe3O4-rich tribofilms to investigate the effect of microconstituents, temperature and atmosphere on the friction coefficient during pin-on-disc tribotest

“…At the same time, the lattice fringe length decreases, indicating the breakup of the hexagonal graphite crystal structure into nanocrystalline regions, finally producing amorphous graphiteMoronov et al, [69]. In 2021, Mavridou et al [70] used Raman spectroscopy to evaluate the wear of graphite lubricants in brake pads. The results indicated that the wear of the graphite takes place in two stages: (1) transformation of crystalline to nanocrystalline graphite; (2) subsequent amorphization.…”

Tribological performance evaluation of slag waste filled phenolic composites for automotive braking applications

“…[6,7] The fillers are present to improve the material's manufacturability and lower its overall cost. [8,9] Although fillers are not as crucial as other elements, they play an essential function in changing certain tribo-characteristics of the brake composite. One of the most frequent fillers is barium sulphate, which occurs naturally as the minerals barite or barites.…”