Friction and wear behaviors of Ni3Al metal matrix self-lubrication composites prepared by laser melting deposition

Abstract

In order to improve the tribological perofrmance of Ni3Al metal matrix composites, the effects of preparation process on the friction and wear behaviors are investigated. Ni3Al self-lubrication metal composites (NMCs) containing 2.0 wt% graphene nanoplatelets (GNPs) were prepared by laser melting deposition (NA-LMD) and sparking plasma sintering (NA-SPS). Rotating sliding tests under different applied loads are conducted to study the friction and wear behaviors. The results show that, compared with NA-SPS, GNPs can be well integrated with NA-LMD substrate whose microstructure is more compact, which is attributed to the sufficient alloying reaction, as well as the layer and layer deposition principle of laser technology. Due to the excellent toughness and strength, the worn surfaces of NA-LMD after tests exhibit smooth and flat morphologies and have no significant pits and microholes. The more dense and thick tribo-layer without significant material deformation is formed beneath the worn surface of NA-LMD to improve the wear resistance performance. Whereas the mechanical properties of NA-SPS become poor due to the uncompacted microstructure and the existence of microholes caused by insufficient alloying reaction. Therefore, the friction coefficients and wear rates of NA-LMD are lower than those of NA-SPS when under the role of heavy and repeated sliding contact loads.