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

Kachit, Mahmoud; Kopp, A.; Adrien, Jérôme; Maire, Éric; Boulnat, Xavier

doi:10.1016/j.jmrt.2022.08.003

Cited by 11 publications

(7 citation statements)

References 47 publications

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“…Previous work reported in the literature, where 316L scaffolds were produced by DIW showed a σ y = 31.7 MPa, for a total porosity of 52.4%. [ 42 ] The higher compression strength of our scaffolds can be correlated to the higher density of the struts, as shown in Figure 10. Indeed, the scaffolds produced in previous work [ 42 ] showed a bimodal porosity, where struts are porous due to partial sintering.…”

Section: Resultsmentioning

confidence: 85%

“…[42] The higher compression strength of our scaffolds can be correlated to the higher density of the struts, as shown in Figure 10. Indeed, the scaffolds produced in previous work [42] showed a bimodal porosity, where struts are porous due to partial sintering. Microhardness tests performed on the AISI316L-B1 section showed an average value of 177 AE 15 HV, in good agreement with literature data of DIW-printed AISI 316L specimens.…”

Section: Mechanical Propertiesmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 93%

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Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices

Biasetto

Elsayed

2022

Adv Eng Mater

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The production of metallic components by additive manufacturing (AM) technologies is today recognized as a standardized method, [1][2][3][4] especially when direct energy deposition (DED) and powder bed fusion (PBF) processes are employed. For instance, AM parts are currently produced by PBF and commercialized by GE Aviation; [5] by 2027 52% revenues of AM are expected to be covered by the aerospace, automotive, and energy sectors. [6] The difference between DED and PBF lies in the powder delivery mechanisms: in DED, the powder can be delivered as is or as a filament and melted on flight by a heat source, in PBF technologies a powder bed is selectively sintered (SLS) or melted (SLM) by a laser or electron beam (EBM). [6] The common points of PBF technologies are the use of micron-size gas atomized powders and the direct melting or sintering of the powders. If this represents an advantage in terms of printable geometries and production time, in contrast, the methods hide several side back effects: the need for a protective atmosphere to avoid oxidation, not all metals or alloy can be melted or sintered by the laser or electron beam power source, during printing hightemperature cooling rates (10 4 -10 5 K s À1 ) are responsible for the formation of metastable microstructures with consequences on the mechanical properties (anisotropy). The powders delivery mechanism does not allow the production of closed hollow shapes, so the laser path is responsible for poor control of surface roughness.In addition, PBF processes are not suitable for multi-material 3D printing, being this the next challenge for AM technologies. [7] For instance, powders delivery systems need to be redesigned to grant for proper multi-material combination.Another class of emerging technologies to 3D print metallic components are those classified as extrusion-based, where a metallic-based filament or paste is extruded through a nozzle at mild or room temperature. In both cases, gas-atomized metallic powders are mixed with a polymeric binder to obtain an extrudable filament or paste. In the first case, the technology is called fused deposition modeling (FDM, used for rapid prototyping) or fused filament fabrication (FFF), while in the second case it is called direct ink writing (DIW).FFF and DIW show the advantage of printing at mild or room temperature and the versatility to use more filaments or pastes, for instance, to 3D print multi-material components; the printed part must undergo a de-binding and sintering treatment to remove the polymeric binder and to densify the metallic powders into the final part. The preparation of a homogeneous and printable filament or paste remains one of the key points of these techniques, so de-binding and sintering must grant for the absence of organic binder residues. Sintering at high

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Section: Resultsmentioning

confidence: 85%

Section: Mechanical Propertiesmentioning

confidence: 75%

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Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices

Biasetto

Elsayed

2022

Adv Eng Mater

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“…properties, in particular in terms of the nature of the printed material and particle size. Indeed, all classes of materials can be shaped using these processes: polymers, [40,41] ceramics, [42][43][44][45] metals [46][47][48] and even composites, [49,50] and multi-materials. [51,52] The extruded particles can range from 20 nm [46] to over 200 μm depending on the desired resolution.…”

Section: Introductionmentioning

confidence: 99%

“…As an alternative, 3D printing processes using material extrusion, such as fused‐filament fabrication (FFF) or direct‐ink writing (DIW), can process feedstocks with a larger range of properties, in particular in terms of the nature of the printed material and particle size. Indeed, all classes of materials can be shaped using these processes: polymers, [ 40,41 ] ceramics, [ 42–45 ] metals [ 46–48 ] and even composites, [ 49,50 ] and multi‐materials. [ 51,52 ] The extruded particles can range from 20 nm [ 46 ] to over

200 μ m

depending on the desired resolution.…”

Section: Introductionmentioning

confidence: 99%

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

2022

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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.

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Ink Tuning for Direct Ink Writing of Planar Metallic Lattices

2023

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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.

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

Cited by 11 publications

References 47 publications

Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices

Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices

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

Ink Tuning for Direct Ink Writing of Planar Metallic Lattices

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