Enhanced flow properties of SiO ₂ nanoparticles coated low-cost hydrogenation-dehydrogenation Ti-6Al-4V powder for powder bed fusion process

Powder bed fusion (PBF) is a metal additive manufacturing process known for high-dimensional accuracy and design flexibility. Spherical powders, often used in PBF, provide appropriate flowability for uniform layer recoating but are limited by low yields and high costs. In this research, low-cost hydrogenation-dehydrogenation (HDH) Ti-6Al-4V powder was used for the PBF process. To overcome its drawback of low flow properties, a simple dry-coating process of hydrophobic SiO 2 nanoparticles on the surface of the HDH Ti-6Al-4V powders was proposed. Surface-modified HDH Ti-6Al-4V powder showed enhanced flow properties, which can be utilised in the PBF process under standard conditions such as recoating speed (30 mm/s). X-ray photoelectron spectroscopy was conducted to examine the bonding between the powders and particles after dry coating. The additive-manufactured sample exhibited a relative density of over 99.8% and a 36.0% increase in Vickers hardness compared to the spherical Ti-6Al-4V powder, due to the grain refinement effect of the SiO 2 nanoparticles.