Selective laser melting of novel nanocomposites parts with enhanced tribological performance

Abstract

Selective laser melting (SLM) was applied to build the nanocrystalline TiC/Ti nanocomposites parts. The influence of linear laser energy density (λ) on densification, microstructures, microhardness, and tribological performance of SLM-processed parts was investigated. It showed that the densification rate of TiC/Ti parts remained above 97% using linear laser energy density λ≥600 J/m. A decrease in λ caused the balling effect and lowered densification. The TiC reinforcement in SLM-processed parts had unique microstructures distinctly different from the initial nanoparticle morphology. A proper decrease in λ led to the formation of the uniformly dispersed nanoscale lamellar TiC reinforcement. The SLM-processed parts had an enhanced microhardness of 566 HV_0.2, a low average coefficient of friction (COF) of ~0.25 and a reduced wear rate of ~4×10⁻¹⁶ m³/(Nm) during dry sliding tests. The insufficient SLM densification at a low λ and the disappearance of nanoscale TiC reinforcement at a high λ generally lowered the tribological performance of SLM-processed TiC/Ti parts.

Keywords:

• additive manufacturing (AM)
• selective laser melting (SLM)
• nanocomposites
• tribological performance

Acknowledgements

The present work is financially supported by the National Natural Science Foundation of China (No. 51104090) and the Qing Lan Project, Jiangsu Provincial Department of Education, China. G.Q. Zhang appreciates the support from the Innovation Base (Laboratory) Open Foundation for Graduate Students of Nanjing University of Aeronautics and Astronautics (No. kfjj120208).