Enhancing Wear Resistance of AA7075/SiC/Fly Ash Composites Through Friction Stir Processing

In this study, the wear behavior of AA7075/silicon carbide/fly ash hybrid surface composites processed with a clean and green friction stir processing technique was investigated. The microstructure of the composites was investigated to determine the particle dispersion. Wear tests using a pin-on-disc tribometer were conducted, and wear tracks and debris analyses were conducted using scanning electron microscopic imaging, EDX, and mapping. The wear rate of the composites was higher in the case of the composites with agglomerated zones, which led to the loose SiC/fly ash particles pulling out during the action of dry sliding. However, on the other hand, the wear resistance was improved in the composites with uniformly distributed SiC/fly ash particles. The hard SiC/fly ash particles acted as optimized load-bearing asperities and induced more wear resistance during the action of dry sliding against the mating plate, which was made of mild steel. In the case of the well-dispersed composites, the wear mechanisms shifted from fretting fatigue and adhesion to abrasion. The presence of a high Fe content in the wear debris was confirmed in the most wear-resistant composite sample, S-20, which was produced with the following parameters: tool rotation (w) of 1000 rpm, tool traverse (v) of 40 mm/min, hybrid ratio (HR) of 75:25, and a volume percentage of reinforcements (vol.%) of 8.