Microstructure and tribological behavior of Al–12Si – Nano graphene composite fabricated by laser metal deposition process

Abstract

To improve the wear resistance of the Al-based alloys and extend its application spectrum, graphene nano-platelets (GNPs) reinforced Al–12Si matrix composites were fabricated by laser melting deposition (LMD) technology. The microstructure, wear morphologies and surface roughness were characterized by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) setups and 3D confocal microscopy. The microhardness and high-speed reciprocating frictional properties both Al–12Si and GNPs/Al–12Si composites were evaluated. The addition of graphene significantly refines the microstructure and improves the wear resistance of the matrix. The formation of a relatively stable mechanically mixed layer (MML) reduces the contact area between the friction pair material and the wear surface, the wear rate and roughness of the Al–12Si – 0.5 wt% GNP reinforced composites decrease with the increase of sliding speed, and the wear mechanism changes from adhesive wear accompanied by abrasive wear to fatigue wear. Meanwhile, as the load increases, the wear rate and roughness increase. The wear mechanism of the composite changes from abrasive wear to a mixed mode (combination of both adhesive and abrasive). This research not only offers valuable information about the Al–Si-based composites but provides theoretical light on their industrial applications.

Keywords

• Nano graphene nano-platelets (GNPs)
• Al–12Si
• Laser melting deposition (LMD)
• Microstructure
• Wear resistance