Friction surfacing of Al2O3 reinforced aluminium coatings on low carbon steel with microstructural and tribological characterization

Friction surfacing (FS) was employed to create Al–7.5 wt% Al 2 O 3 metal matrix composite coatings on low carbon steel (AISI 1018), enhancing surface performance by solid-state processing. Two parameter sets were examined to identify their effects on coating microstructure and tribology. SEM–EDS showed dense, defect-free coatings with uniform reinforcement particle distribution, good metallurgical bonding, and a narrow compositional transition across the coating–substrate interface. The higher rotational speed and axial load promoted greater material plasticization, resulting in improved coating continuity and consolidation. The EBSD investigation showed significant grain refinement from 12.6 μm in the consumable rod to 8.6 μm in the coating, indicating dynamic recrystallization during FS. Effective microstructural stabilization was confirmed by a considerable rise in high-angle grain boundary fraction. The combination of grain refinement, strain hardening, and dispersion strengthening by Al 2 O 3 particles significantly increased microhardness from 160 HV for the substrate to 250 HV for the coating. Dry sliding tribological investigations indicated significant weight loss, specific wear rate, and coefficient of friction reductions compared to the substrate. The improved coating reduced weight loss by 67.2% and specific wear rate by 71.8%. The better performance at higher energy settings shows how FS process parameters improve coating integrity, microstructural refinement, and tribology.