Mechanical Testing of Zinc Specimens made from Laser Powder Bed Fusion for Use as Biodegradable Implants

Open Access
- Author:
- Molnar, Thomas
- Area of Honors:
- Mechanical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Guhaprasanna Manogharan, Thesis Supervisor
Jean-Michel Mongeau, Thesis Honors Advisor - Keywords:
- Laser Powder Bed Fusion
Zinc
Tensile Strength
Osteogenic Material
Biodegradable Implant - Abstract:
- This thesis investigates the optimal laser powder bed fusion (LPBF) processing parameters for fabricating pure zinc components with a target density of 7.14 g/mL. A 4x4 matrix was developed, varying laser power (84-99 W) and scan strategies (single or double pass), while maintaining a constant scan speed of 350 mm/s, hatch spacing of 0.11 mm, and layer thickness of 0.06 mm. Volumetric Energy Density (VED) was calculated to ensure appropriate energy distribution, and Archimedes density testing was employed to assess the quality of the fabricated cubes. The study found that while the double-scan strategy led to higher densities, it also caused excessive heat accumulation, resulting in build delamination. Therefore, further testing focused on single-scan samples, with sample #1 (99 W, single pass) achieving the closest density to the expected theoretical value. Microstructural characterization and mechanical testing followed, with tensile bars showing an ultimate tensile strength (UTS) of 72.88 MPa—nearly double the UTS of zinc produced by traditional methods. Rockwell B hardness testing confirmed the hardness of the material, resulting in around 27 HRB, and when compared with other studies and against other specimens it was revealed that these values are influenced by the build direction and laser parameters. The results indicate that LPBF can significantly enhance the mechanical properties of zinc compared to traditional manufacturing, and further optimization of laser parameters could yield even greater improvements. This work establishes a foundational understanding of processing pure zinc via LPBF and provides valuable insights for future research into parameter refinement and microstructure-property relationships.