Fabrication and characterization of radially graded porous titanium/tantalum via selective laser melting

Abstract:

Radially graded porous titanium / tantalum orthopedic implants fabricated by additive manufacturing technology have golden prospects. A cylindrical radially graded porous scaffold with an average porosity of 70% was built by using the triply minimal surfaces (TPMS) modeling methods, and the porosity gradually decreases from the central axis (90%) to the circumferential surface (30%). Selected laser melting (SLM) process was used to fabricate this scaffold. Optical microscopy, scanning electron microscopy, and Micro-CT results show that the SLM titanium/tantalum were consistent with the design models. The porosities of the SLM radially graded porous titanium / tantalum are 73.18% and 68.18% respectively. The mechanical test results show that the elastic modulus of radially graded porous titanium / tantalum are 3.96 ± 0.19GPa and 3.47 ± 0.25GPa respectively, and the compressive strength are 90.83 ± 3.35MPa, 93.27 ± 1.24MPa respectively. Both of them are significantly higher than those of homogeneous porous titanium / tantalum respectively. (Homogeneous porous titanium with an average porosity of 70.11% has an elastic modulus of 2.34 ± 0.48GPa and a compressive strength of 67.63 ± 1.33MPa; Homogeneous porous tantalum with a porosity of 65.39% has an elastic modulus of 1.69 ± 0.49GPa and a compressive strength of 68.56 ± 0.41MPa). In vitro cytocompatibility experiments show that both radially graded porous titanium and tantalum have good biocompatibility and they are suitable for the adherent and growth of mesenchymal stem cells and muscle cells. The radially graded porous titanium / tantalum fabricated by the SLM process has more similar structure and properties to natural bone tissue than homogeneous porous titanium / tantalum, and both of them are an ideal substitute for bone defect repair.

Key words:triply minimal surfaces, radially graded porous titanium/tantalum, selective laser melting, mechanical properties, biocompatibility