Selective laser melting of pure Zn with high density for biodegradable implant manufacturing

Zinc and its alloys constitute the new generation of biodegradable metallic materials for biomedical implants. Biodegradable implants of Zn, customized for the specific patient can be potentially realised through additive manufacturing processes such as selective laser melting (SLM). However, Zn is characterized by low melting and boiling points, resulting in high porosity in the build parts. In this work, the SLM of pure Zn powder is studied to improve part density. A flexible prototype SLM system was used to determine process feasibility under different atmospheric conditions. Working in a closed chamber under inert gas was found to be inadequate. Process stability was obtained in an open chamber with an inert gas jet flow over the powder bed. The effect of laser process parameters and powder size was studied in this condition. Part density over 99% was achieved in optimal processing conditions.