SiO 2 nanoparticle-coated Ti-6Al-4V spherical powder for powder bed fusion additive manufacturing process

Abstract

This study investigated a nanoparticle coating method to simultaneously improve the flow characteristics of spherical powder used in powder bed fusion (PBF) additive manufacturing (AM) and the mechanical properties of the resulting additively manufactured specimens. By employing a simple surface dry-coating of nano-sized hydrophobic SiO₂ powder, the flowability of Ti-6Al-4V powder was enhanced. Additionally, the mechanical properties including strength and hardness of the Ti-6Al-4V alloy produced via laser powder bed fusion (L-PBF) were improved by incorporating hydrophobic SiO₂. The spherical Ti-6Al-4V powder was mixed with 0.1 wt.% SiO₂ using a 3D tubular mixer, and subsequent microstructural analyses confirmed the uniform dispersion of oxide particles. Various cubic specimens were then fabricated using the PBF process to optimize AM parameters. The relative density of the additively manufactured samples revealed that the highest density sample achieved approximately 99%. Tensile tests demonstrated that specimens fabricated from the SiO₂-coated Ti-6Al-4V powder exhibited a maximum tensile strength of 1188 MPa and an elongation of 11.4%, representing an 11.0% improvement in tensile strength compared to samples without SiO₂ addition. The enhanced mechanical properties and subsequent microstructural analysis suggest that the increase in strength is attributable to oxide dispersion strengthening induced by SiO₂.