Sinter‐Based Additive Manufacturing of Graded Porous Titanium Scaffolds by Multi‐Inks 3D Extrusion

Abstract

A 3D printing approach to design and produce cellular scaffolds with a precise tunable pore architecture, in terms of size, fraction, and interconnectivity is reported. Different metallic inks are formulated by mixing hydrogel with Ti–6Al–4V atomized powders of various sizes. After 3D printing by direct‐ink writing (DIW) followed by debinding and sintering, the fraction and size of macropores (, designed by computer‐aided design (CAD)) and micropores (, remaining after sintering), the roughness and the microstructure are determined by high‐resolution X‐ray tomography and electron microscopy, and correlated to the initial powder size. It is shown that playing with initial powder size allows designing different pore architectures, from interconnected micropores to fully dense filaments. These phenomena are combined with a multi‐inks DIW approach to fabricate architectured structures with graded microporosity. This new route is promising for the production of functional materials, such as biomedical scaffolds or implants, with tunable osseointegration, stiffness, and strength. The micropores could also be loaded with active molecules and positioned according to release needs.

Optimization of Pin Type Single Screw Mixer for Fabrication of Functionally Graded Materials

“…This strategic composition mitigates the issue of abrupt interfaces between materials, thus enabling the full exploitation of the inherent potential of each material [3][4][5]. Specifically, ceramic-based FGMs, when integrated with flexibility-oriented additive manufacturing processes, are becoming increasingly crucial in a variety of critical fields, including military [6][7][8], bioengineering [9][10][11][12], energy [13,14], and aerospace [15][16][17][18].…”

Ink Tuning for Direct Ink Writing of Planar Metallic Lattices

“…Both in refs. [12,14], Pluronic F127 in distilled water was used as binder: in this case, a highly temperature‐dependent hydrogel is formed. [ 15 ] More specifically, Pluronic F127, the trademark for PEO 100 ‐PPO 65 ‐PEO 100 copolymer (with PEO = PolyEtylenOxide, PPO = PolyproPylenOxide) behaves like a liquid at low temperature ( T = 5 °C) and like a gel at body temperature ( T = 37 °C) for concentration exceeding the 20% w/w.…”

“…In ref. [14], the authors studied the effect of powder size and powder size distribution on the final porosity of scaffolds for Ti64 gas-atomized powder inks. Small-sized powders with a narrow size distribution (0.2-7 μm) showed struts with higher density after sintering compared to powders with a coarse powders size distribution in the range of 2-70 μm.…”

“…In this case, the variation of ink rheological properties (increase of viscosity, yield stress, and G' in the linear viscoelastic region) was attributed to the increase of Y 2 O 3 content; however, there was also a decrease in powders size distribution ( Both in refs. [12,14], Pluronic F127 in distilled water was used as binder: in this case, a highly temperature-dependent hydrogel is formed. [15] More specifically, Pluronic F127, the trademark for PEO 100 -PPO 65 -PEO 100 copolymer (with PEO = PolyEtylenOxide, PPO = PolyproPylenOxide) behaves like a liquid at low temperature (T = 5 °C) and like a gel at body temperature (T = 37 °C) for concentration exceeding the 20% w/w.…”

Biological and Mechanical Response of Graphene Oxide Surface‐Treated Polylactic Acid 3D‐Printed Bone Scaffolds: Experimental and Numerical Approaches

“…Fused deposition modeling (FDM), stereolithography, powder 3D printing, selective laser sintering/melting, and 3D-bioprinting are all possible using techniques for in vitro and in vivo applications. [14,15] The AM technique enables researchers to overcome the low complexity and poor similarity of the scaffolds to human bones. In the last years, many models and mathematical shapes have been presented to make scaffolds much quite close to the natural tissues.…”