The effect of SLM parameters on geometrical characteristics of open porous NiTi scaffolds

Speirs, Mathew; Dadbakhsh, Sasan; Buls, Sam; Kruth, Jean Pierre; Humbeeck, Jan Van; Schrooten, Jan; Luyten, Jan

doi:10.1201/b15961-57

Cited by 14 publications

(14 citation statements)

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“…Ideally, the struts within the porous structure should have the characteristics of a dense NiTi with minimal structural defects [101]. Therefore, to fabricate engineered porosity, it is important that the laser parameters (e.g., laser power-P, scanning speed-, hatch distance-h, layer thickness-t) that are chosen to fabricate engineered porous parts should be able to process dense parts as well, such that the pore walls will be fully dense [43].…”

Section: Optimum Laser Parameters To Produce Engineered Porous Am Nitimentioning

confidence: 99%

“…Speirs et al [43] investigated the effect of two different sets of laser parameters, one with energy input of 111J/mm 3 (P=40 Watt, v=160 mm/s, h=75 μm) and another with 126 J/mm 3 (P=250 Watt, v=1100 mm/s, h=60 μm), on the level of geometrical variation of SLM Ni55.2Ti scaffolds. It should be noted that both sets of parameters were capably of fabricating fully dense parts.…”

Section: Optimum Laser Parameters To Produce Engineered Porous Am Nitimentioning

confidence: 99%

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Fabrication of NiTi through additive manufacturing: A review

Elahinia

Moghaddam

Andani

et al. 2016

Progress in Materials Science

637

228

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Nickel-titanium (NiTi) is an attractive alloy due to its unique functional properties (i.e., shape memory effect and superelasticity behaviors), low stiffness, biocompatibility, damping characteristics, and corrosion behavior. It is however a hard task to fabricate NiTi parts because of the high reactivity and high ductility of the alloy which results in difficulties in the processing and machining. These challenges altogether have limited the starting form of NiTi devices to simple geometries including rod, wire, bar, tube, sheet, and strip. In recent years, additive manufacturing (AM) techniques have been implemented for the direct production of complex NiTi such as latticebased and hollow structures with the potential use in aerospace and medical applications. It worth noting that due to the relatively higher cost, AM is considered a supplement technique for the existing. This paper provides a comprehensive review of the publications related to the AM techniques of NiTi while highlighting current challenges and methods of solving them. To this end, the properties of conventionally fabricated NiTi are compared with those of AM fabricated alloys. The critical steps toward a successful manufacturing such as powder preparation, optimum laser parameters, and fabrication chamber conditions are explained. The microstructural characteristics and structural defects, the influencing factors on the transformation temperatures, and functional properties of NiTi are highlighted to provide and overview of the influencing factors and possible controlling methods. The mechanical properties such as hardness and wear resistance, compressive behaviors, fatigue characteristics, damping and shock absorption properties are also reported. A case study in the form of using AM as a promising technique to fabricate engineered porous NiTi for the purpose of creating a building block for medical applications is introduced. The paper concludes with a section that summarizes the main findings from the literature and outlines the trend for future research in the AM processing of NiTi.

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Section: Optimum Laser Parameters To Produce Engineered Porous Am Nitimentioning

confidence: 99%

Section: Optimum Laser Parameters To Produce Engineered Porous Am Nitimentioning

confidence: 99%

Fabrication of NiTi through additive manufacturing: A review

Elahinia

Moghaddam

Andani

et al. 2016

Progress in Materials Science

637

228

View full text Add to dashboard Cite

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“…Powder layers are melted upon one another locally with a laser beam until part completion [1]. NiTi has been identified as a promising material for SLM aimed at porous biomedical applications [2][3][4], especially considering its current manufacturing difficulties [5].…”

Section: Introductionmentioning

confidence: 99%

On the Transformation Behavior of NiTi Shape-Memory Alloy Produced by SLM

Speirs

Wang

Baelen

et al. 2016

Shap. Mem. Superelasticity

110

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Selective laser melting has been applied as a production technique of nickel titanium (NiTi) parts. In this study, the scanning parameters and atmosphere control used during production were varied to assess the effects on the final component transformation criteria. Two production runs were completed: one in a high (*1800 ppm O 2 ) and one in a low-oxygen (*220 ppm O 2 ) environment. Further solution treatment was applied to analyze precipitation effects. It was found that the transformation temperature varies greatly even at identical energy densities highlighting the need for further in-depth investigations. In this respect, it was observed that oxidation was the dominating factor, increased with higher laser power adapted to higher scanning velocity. Once the atmospheric oxygen content was lowered from 1800 to about 220 ppm, a much smaller variation of transformation temperatures was obtained. In addition to oxidation, other contributing factors, such as nickel depletion (via evaporation during processing) as well as thermal stresses and textures, are further discussed and/or postulated. These results demonstrated the importance of processing and material conditions such as O 2 content, powder composition, and laser scanning parameters. These parameters should be precisely controlled to reach desired transformation criteria for functional components made by SLM.

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“…This is evident in Figure 3.15, where the scaffolds made by a higher scanning speed and adjusted to a higher power (see HP zone) show a larger mismatch than that of scaffolds made with lower speed and power (see LP zone) parameters but with a comparable laser energy density. 49 Because the laser does not reach the equilibrium speed during fast scanning, the effective energy density will be higher, resulting in a larger melt pool and larger geometrical mismatches.…”

Section: Biomedical Scaffoldsmentioning

confidence: 99%

“…Comparison of nickel-titanium scaffolds made by LP parameters (low speed, low power: P = 40 W, v = 160 mm/s) and HP parameters (high speed, high power: P = 250 W, v = 1100 mm/s), with asdesigned CAD file (180 µm strut thickness): (A) top view (x-y section) and (B) side view (x-z section) 49. …”

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confidence: 99%