Ti6Al4V Scaffolds Produced by Selective Laser Melting: Influence of Chemical Etching on Powder Removal and Mechanical Properties

Additive manufacturing is being used to produce medical orthopedic implants. However, the Ti6Al4V scaffolds formed by selective laser melting (SLM) limited by surface roughness. The chemical etching method have used to treat Ti6Al4V owing to the liquidity. The aim of this study is to investigate the effects of different concentration of hydrofluoric and nitric acids mixtures and times on the surface morphology and mechanical properties of Ti6Al4V scaffolds formed by SLM. The results showed that with the increase of concentration of etchant and times, the surface roughness decreased, and the mechanical properties decreased. Different concentration of etchant be conducive to remove the different shapes of adhering powder. As the best condition of concentration is 1:8 and the time is 16 min, the surface roughness is 8.4 μm, the adhering powder of 96% are removed. Too much time can cause overcorrosion. However, chemical etching weaken the strength of the Ti6Al4V scaffolds in comparison with an as-built structure. The addition of nitric acid can effectively prevent the degradation of mechanical properties by dissolving hydrogen.