Laser-based powder bed fusion of Ti-6Al-4V powder modified with SiO2 nanoparticles

Abstract

In laser-based powder bed fusion of metals (PBF-LB/M), residual oxygen in the processing atmosphere is regarded as disruptive and disadvantageous for the manufacturing process and the resulting component properties. A novel approach to eliminate residual oxygen is to add small amounts of silane to the argon process gas. Silane eliminates residual oxygen and forms SiO2 nanoparticles, which in turn can be incorporated into the powder during the process. It is therefore necessary to evaluate the influence of these nanoparticles admixed to the metal powder. In this work, Ti-6Al-4V powder was modified with pyrogenic SiO2 nanoparticles generated by the reaction of a silane argon gas mixture with ambient air. Modified and unmodified powder was analyzed and processed using statistically designed experiments. An improvement of the flow rate according to DIN EN ISO 4490 (from 33.3 to 32.5 s/50 g) and increase of apparent density according to DIN EN ISO 3923 (from 2.52 to 2.58 g/cm3) could be observed after powder modification. No statistically significant effects of the modification on roughness, porosity, and hardness were found. The results demonstrate that powder modification using silane can lead to enhanced flowability without affecting the PBF-LB processing window of Ti-6Al-4V.