Benchmarking of additive manufacturing technologies for commercially-pure-titanium bone-tissue-engineering scaffolds: processing-microstructure-property relationship

Extrusion, Debinding and sintering of a commercial pure titanium ink for robocasting

“…The experimental mass loss after debinding at this temperature was 90 % of the theoretical expected. The efficiency in the debinding was superior to that observed previously when chitosan was used as binder [6] and similar to that observed with Pluronic [7,8]. Figure 8 shows the microstructure of the sinter sample, which exhibited equiaxed alpha titanium grains with size of 67 m in average, few small pores and no evidences of carbide or oxide inclusions, as proof of titanium purity after sintering.…”

“…Figure 8 shows the microstructure of the sinter sample, which exhibited equiaxed alpha titanium grains with size of 67 m in average, few small pores and no evidences of carbide or oxide inclusions, as proof of titanium purity after sintering. This is a significant step forward respect the use of Pluronic as binder, which generates carbide inclusions [7]. Chemical purity was confirmed by XRD and EDX analysis, showing hexagonal titanium as the only crystalline phase and 95.5 wt% of titanium, 3.7 wt% of oxygen, 0.8 wt% of carbon and no signal of nitrogen in the metallographic cross-section of the sinter sample.…”

Structural and Material Determinants Influencing the Behavior of Porous Ti and Its Alloys Made by Additive Manufacturing Techniques for Biomedical Applications

“…In [114], the trabecularlike porous Ti-6Al-4V scaffolds with varying irregularities (0.05-0.5 µm) and porosities 49-74% designed through a novel Voronoi-tessellation-based method were manufactured. A different approach [115] provided the benchmarking of SLM and robocasting, as manufacturing methods of scaffolds from commercially pure titanium (CP-Ti). The values of compressive yield strength 75 MPa and effective elastic modulus in compression 7 GPa were shown by the SLM-made scaffold, the values closer to those of the cortical bone as compared to robocasting, whereas the robocasted scaffold presented higher ALP activity than SLM-made scaffolds.…”

“…The results of cell culture indicated that the Ta scaffold was nontoxic, cell proliferation was the highest after the 4th day. In a comparative study of SLM and robocasting method of manufacturing porous scaffolds, [115] the obtained CP-Ti scaffolds possessed high cytocompatibility with no significant differences between the two types of scaffolds, but with a higher rate of ALP activity observed for the Rob-scaffolds. Similar results were obtained in [138] with fibroblasts well attached and spread on the surface of Ti-6Al-4V scaffolds manufactured by direct ink writing (DIW) technology.…”

“…However, the grains formed during the AM process are smaller near the interface with the substrate as compared to the subsurface layers. The mechanical performance of the scaffolds is determined rather by the microporosity than microstructure [115]. The lackof-fusion pores and cracks are the most often observed defects [17].…”