Search

316L and Cu‐based inks are developed to 3D‐printed tetrachiral auxetic structures. The main objectives of the work are to study the effects of powders composition and powder:binder volume ratio on rheological properties and printability of the inks. Following these results, customized Gcode is developed using FullControl Gcode Designer open‐source software to 3D print intricate tetrachiral auxetic structures. The results reported in this work show how powder composition (316L versus Cu) has less effect on the inks' rheological behavior than powder size distribution and powders:binder volume ratio. In terms of rheological parameters, the zero‐shear rate viscosity mainly affects the capability of the printed ink to retain its shape after printing, while the yield stress affects the printability. The printed and sintered auxetic structures achieve the intended lattice‐geometry design. [ABSTRACT FROM AUTHOR]

The focus of the present work is the development of a metallic ink that possesses controlled rheological properties: by keeping printing parameters constant both AISI 316L dense parts and porous scaffolds have been produced. Shrinkage, porosity, and mechanical properties have been studied to evaluate the link between the ink rheological properties and the final part. Depending on binder composition, linear shrinkage ranging from 9% to 22% and porosity from 34 to 7 vol% are measured. Tensile strength for specimens sintered at 1240 °C reach the value of 444 MPa and elongation at a break of 12.3%. These values are still far from additively manufactured AISI 316L parts with powder bed fusion technologies, but represent an improvement compared to previously reported data in the literature for AISI 316L parts 3D printed by DIW. Porous scaffolds with a spanning distance of 1.2 mm are printed and sintered. Porosity of 74 vol% and compression strength of 74 MPa are measured for this set of samples showing how the produced ink represents a valuable alternative to pastes already present in the literature. [ABSTRACT FROM AUTHOR]

Ti6Al4V scaffolds were printed by Direct Ink Writing of a water-based polymeric ink. Different geometries were fabricated in terms of filament size (250 μm, 400 μm and 800 μm) and filament distance (half, same and double the filament size). The designed and actual porosity (total, open and closed), the linear and volumetric shrinkage as well as the microstructure of the scaffolds after sintering were analyzed. The good fitting between designed and actual values of porosity were confirmed both by He-Pycnometry and X-ray micro computed tomography measurements. Results showed that shrinkage decreased with increasing the filament distance over filament size ratio. The microstructure of the scaffolds depended on filament size, showing multiple phases formation for the smallest filament size. The compressive strength behavior was studied experimentally and by computational simulations: the discrepancy between experimental and predicted values of stress-strain compression curves were reflecting the lamellar and acicular phase formation in scaffolds with strut size smaller than 400 μm, whilst they showed a good fitting for scaffolds possessing an equiaxic microstructure. [ABSTRACT FROM AUTHOR]

Ti6Al4V components, for biomedical and aerospace sectors, are receiving a great interest especially after the advent of additive manufacturing technologies. The most used techniques are Selective Laser Sintering (SLS), Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In the current research, we developed 3D-printed Ti6Al4V scaffolds by Direct Ink Writing (DIW) technology. Appropriate ink formulations, based on water-titanium powder suspensions, were achieved by controlling the rheological properties of the developed inks. After printing process, and drying, the printed components were sintered at 1400 °C under high vacuum for 3 h. Highly porous titanium scaffolds (with porosity up to 65 vol%) were produced and different geometries were printed. The influence of the porosity on the morphology, compression strength and biocompatibility of the scaffolds was investigated. • Different scaffolds geometries were printed possessing struts nominal size of 800 micron. • Porosity was designed in order to assess its effect on struts microstructure, compression strength and biocompatibility • We demonstrated the high quality of the produced ink so as the good control on processing parameters. • A preliminary in vitro result indicated that 3D printed Titanium scaffolds allowed cell attachment and proliferation [ABSTRACT FROM AUTHOR]