Effect of Thermal Treatment on the Tribological Performance of Non‐Asbestos Brake‐Pad Composites Containing Quartz‐Composite Stone Polishing Waste

ABSTRACT The primary objective of this study is to evaluate quartz‐composite stone polishing waste as a partial or complete substitute for alumina in non‐asbestos brake pad composites and to investigate the effect of both heat‐treated and untreated waste on the tribological performance of these materials. In the study, resin‐containing quartz waste (RQW) was used in specific compositions following a drying process, while heat‐treated quartz waste (TQW) was utilized in other designated compositions. TQW was obtained by heating a portion of the RQW at 600°C for 12 h. The waste types used as an alternative raw material in compositions have been characterized to determine their particle size and morphology, elemental and mineralogical content, and thermal behavior. Six formulations were manufactured by hot pressing and post‐curing and characterized using SEM–EDS, density, Rockwell R hardness, and SAE J661 Chase testing. Both wastes comprised angular, quartz‐rich particles. Thermal treatment reduced the EDS‐measured carbon content from 12.41 to 7.61 wt% without detectable changes in the quartz‐rich crystalline structure. Quartz‐waste‐containing formulations exhibited normal and hot friction coefficients of 0.588–0.617 and 0.535–0.589, respectively, exceeding the alumina reference values of 0.508 and 0.476. However, their mass losses (6.4%–7.9%) were higher than that of the reference (3.8%). The formulation containing 10 wt% TQW as a complete alumina replacement (Q5) provided the highest hot friction coefficient (0.589), a density of 2.59 g/cm 3 , and a hardness of 103 HRR. A complementary AHP–TOPSIS assessment ranked Q5 first, unchanged under ±10% weight perturbations. Q5 was therefore identified as a promising candidate for further development.