Direct-ink writing and compression behavior by in situ micro-tomography of architectured 316L scaffolds with a two-scale porosity

Abstract

Metallic scaffolds with 3D macroporous architecture were produced by direct-ink writing, an additive manufacturing process, which consists in: (i) ink formulation (ii) 3D layerwise extrusion (iii) debinding and sintering. An easy-handling and CMR-free metallic ink composed of aqueous gel and stainless steel powder was optimized to allow 3D extrusion when keeping stiffness and viscosity for design adequation. Evolution upon sintering under vacuum, resulting in a second-scale micronic porosity, was followed by microscopy and 3D X-ray tomography. The ductile behavior was assessed by in situ compressive test under X-Ray tomography, showing a predominant role of macropores compared to micropores in the filaments. This design method with the same hydrogel can be applied to generate other architectured structures of sinterable alloys.

Keywords

• Direct-ink writing
• Scaffolds
• Porosity
• Compression
• Micro-tomography