Metal Additive Manufacturing Conference 2018

Recent studies have shown that Zn based metal exhibit 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. 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 processing parameters on densification during the Laser Powder Bed Fusion process (L-PBF) of pure Zn, and obtain high density in a reasonable process window. Porosity results by either lack of fusion due to lack of laser energy or by gas entrapment due to excessive evaporation. The side surfaces of cubes are attached with numerous partially melted powders, which deteriorates the surface quality. The arithmetical mean height (Sa) at side surfaces can be reduced after sand blasting from 10.12 μm for as-melted status to 4.83 μm. Lattice structures are obtained stably with a strut diameter of about 500 μm. Cylinders were built up and machined later into the shape of tensile test pieces. The average values of hardness, elastic modulus, yield strength, ultimate strength and elongation are measured as 42 HV, 23 GPa, 114 MPa, 140 MPa, and 10.1% respectively for L-PBF produced pure Zn parts with density over 99.90%.