Effect of Pore Structure on Forming Quality and Performance of Mg-5Zn Magnesium Alloy Porous Bone Repair Scaffold Fabricated by SLM

Abstract:

Four types of Mg-5Zn porous scaffolds with different pore geometries, including body-centered cubic (bcc), the rhombic dodecahedron (RD), gyroid (G), and primitive (P) types, were designed and fabricated using selective laser melting. Their forming quality, compression mechanical properties, and degradation behavior were investigated. Results indicate that the fabricated scaffolds exhibit good dimensional accuracy, and the surface chemical polishing treatment significantly improves the forming quality and reduces porosity error in porous scaffolds. Compared to the ones with rod structures (bcc, RD), the scaffolds with surface structures (G, P) have less powder particle adhesion. The G porous scaffold exhibits the best forming quality for the same design porosity. The predominant failure mode of scaffolds during compression is a 45° shear fracture. At a porosity of 75%, the compression property of all scaffolds meets the compressive property requirements of cancellous bone, while bcc and G structures show relatively better compression property. After immersion in Hank's solution for 168 h, the B-2-75% pore structure scaffold exhibits severe localized corrosion, with fractures in partial pillar connections. In contrast, the G-3-75% pore structure scaffold mainly undergoes uniform corrosion, maintaining structural integrity, and its corrosion rate and loss of compressive properties are less than those of the B-2-75% structure. After comparison, the G-pore structure scaffold is preferred.