Formation Quality, Mechanical Properties, and Processing Behavior of Pure Zinc Parts Produced by Laser-Based Manufacturing for Biodegradable Implants

Recent studies have shown that Zinc (Zn) exhibits promising applications for biodegradable medical implants due to the good combination of biocompatibility, biodegradation rate, and mechanical properties. Only a few recent reports can be found on additive manufacturing of Zn parts. Either the obtained density is too low or the process window is quite narrow due to excessive evaporation. This paper aims to clarify the effect of process parameters on densification during the Laser Powder Bed Fusion (LPBF) processing of pure Zn powder and to obtain high relative density in a reasonable process window. Porosity results either from a lack of fusion due to insufficient laser energy or from gas entrapment due to excessive evaporation. The side faces of cubes are attached by numerous partially melted powder particles, which deteriorates the surface quality. The arithmetical mean height (Sa) on side surfaces can be reduced after sand blasting from 10.12 mm to 4.83 mm for as-melted status. Lattice structures are obtained stably with a strut diameter of about 500 mm. Cylinders were manufactured and machined later into the shape of tensile test specimens. The average values of elastic modulus, yield strength, ultimate strength, and elongation were measured as 35.91 GPa, 101.67 MPa, 113.33 MPa, and 10.8% respectively for LPBF manufactured pure Zn parts with relative density over 99.90%.