Microstructure and wear properties of carbon nanotubes reinforced WE43 composite coating fabricated by laser directed energy deposition

Laser directed energy deposition (LDED) was utilized to incorporate carbon nanotubes (CNTs) into WE43 magnesium alloy, aiming to enhance its wear resistance by leveraging the exceptional mechanical and self-lubricating properties of CNTs. The LDED-prepared CNTs reinforced WE43 composite (CNTs/WE43) coatings were fabricated for evaluating the wear resistance improvement. The microstructure and wear properties of the LDED-prepared CNTs reinforced WE43 composite coating were investigated in comparison to the WE43 coating. The addition of Ni coated CNTs (Ni-CNTs) led to drastic morphologic changes including the emergence of stratified structures and distinct furrow formations. The composite coating exhibited altered segregation patterns, characterized by the presence of filamentous, punctiform, porphyritic, and ring-shaped accumulations of CNTs, Mg24Y5, and Zr cores in both the central and furrow zones. The addition of Ni-CNTs induced a decrease of up to 45.8 % in wear weight loss for the WE43 coating. The friction coefficient versus the applied loads of the WE43 and CNTs/WE43 coatings showed an opposite trend. The incorporation of CNTs significantly improved the wear resistance of the WE43 coating by enhancing its ability to resist plastic deformation, forming a protective carbon film, and providing self-lubricating effects.