Keeping sustainability in mind, the need to recycle/reuse industrial waste is of paramount concern. Numerous industrial wastes like red mud and fly ash have already been extensively employed in automotive brake pads, yielding desirable tribological characteristics. These unusual, yet effective additions, have paved a path to explore and utilize alternative kinds of wastes in braking applications. One such example is the waste generated during the aluminium anodizing process, termed aluminium anodizing waste (AAW). Currently, the AAW is being utilized in the field of construction (bricks). However, a large chunk of the waste remains underutilized, generating environmental and economic problems. Furthermore, the AAW remains unexploited, as its minor constituents keep varying, depending on the agents utilized in the anodizing process. Additionally, a streamlined procedure of storage and treatment of this waste is still in its nascent stage. Taking this into consideration, the present study focuses on the storage, characterization, and utilization of AAW in a low metallic friction material composition, with only the essential constituents. The friction material composition was selected to highlight the role of the AAW. The AAW was subjected to initial treatment and an appropriate procedure was established for safe storage. Next, the AAW was characterized using TGA, FTIR, SEM/EDS, and XRD to obtain its composition and particle morphology. Prioritizing economic feasibility, the powder properties of the waste (heat treatment and particle size) were determined and then subjected to preliminary dry sliding wear tests and emission analysis on a pin on disc tribometer at a constant contact pressure of 1 MPa, sliding velocity of 1.51 m/s, and at room temperature. The testing conditions were selected to replicate mild braking conditions in automotive applications. The tests were compared to a reference composition containing alumina instead of AAW. The worn surfaces of the pairings were evaluated through SEM/EDS analysis to understand the nature and the characteristics of the friction layer. It was observed that the AAW behaved as an abrasive, similar to the functioning of alumina. Moreover, the AAW containing composition had a similar friction coefficient, wear, and average particle concentration of emissions, when compared to the reference alumina composition. The properties of the friction layer of both the compositions were fairly similar to each other. Through this initial investigation, the prospect of AAW utilization as an alternative for abrasives in brake pads could be further explored through additional specific dynamometric bench tests to obtain relevant data for automotive braking applications.

University of Trento: Dr. Priyadarshi Jayashree, Prof. Giovanni Straffelini