Low-temperature gas nitriding effects on mechanical and biological properties of open-porous pure titanium produced by robotic micro-extrusion

Low-temperature gas nitriding effects on mechanical and biological properties of open-porous pure titanium produced by robotic micro-extrusion

WoS Article

Direct ink writing (DIW) micro-extrusion additive manufacturing (AM), with its ability to create hierarchically porous metallic structures, is emerging as a key technique in bone repair research. Through controlled sintering, both closed and open microporosities can be tailored within the macroporous metamaterials. This study investigates how low-temperature gas nitriding (500-700 degrees C for 5 and 10 h) affects the mechanical and biological properties of DIW Ti materials with similar to 21% open microporosity, resulting in volumetric nitriding. The flexural behaviour of the microporous filaments, the basic DIW building units, was evaluated by three-point-bending. Nitriding at 500 degrees C and 600 degrees C for 10 h increased the flexural modulus by 25% compared to as-sintered filaments, while flexural strength decreased by 6% and fracture strain by 36%. At 700 degrees C, over-nitriding of isolated sintering necks caused significant reductions in flexural strength and fracture strain, consistent with the enhanced nitriding efficiency observed above 620 degrees C in thermogravimetric measurements. Biological studies on small disc samples showed that nitriding does not impair cellular responses. These findings demonstrate the potential of gas nitriding to functionalize porous AM titanium for biomedical and engineering applications.

Direct ink writing (DIW) micro-extrusion additive manufacturing (AM), with its ability to create hierarchically porous metallic structures, is emerging as a key technique in bone repair research. Through controlled sintering, both closed and open microporosities can be tailored within the macroporous metamaterials. This study investigates how low-temperature gas nitriding (500-700 degrees C for 5 and 10 h) affects the mechanical and biological properties of DIW Ti materials with similar to 21% open microporosity, resulting in volumetric nitriding. The flexural behaviour of the microporous filaments, the basic DIW building units, was evaluated by three-point-bending. Nitriding at 500 degrees C and 600 degrees C for 10 h increased the flexural modulus by 25% compared to as-sintered filaments, while flexural strength decreased by 6% and fracture strain by 36%. At 700 degrees C, over-nitriding of isolated sintering necks caused significant reductions in flexural strength and fracture strain, consistent with the enhanced nitriding efficiency observed above 620 degrees C in thermogravimetric measurements. Biological studies on small disc samples showed that nitriding does not impair cellular responses. These findings demonstrate the potential of gas nitriding to functionalize porous AM titanium for biomedical and engineering applications.

Porous titanium; Direct ink writing; Gas nitriding; Three-point-bending; Cell culture

Porous titanium; Direct ink writing; Gas nitriding; Three-point-bending; Cell culture

SLÁMEČKA, K.; DROTÁROVÁ, L.; OLIVER URRUTIA, C.; TKACHENKO, S.; REMEŠOVÁ, M.; GEJDOŠ, P.; ČELKO, L.; MONTUFAR JIMENEZ, E.

01.06.2025

SURFACE & COATINGS TECHNOLOGY

505

Swiss Confederation

12

https://www.sciencedirect.com/science/article/pii/S0257897225003585