Surface-oxidized, freeze-cast cobalt foams: Microstructure, mechanical properties and electrochemical performance

Park, Hyeji; Cho, Hoon Hwe; Kim, Kyungbae; Hong, Kicheol; Kim, Jae‐Hun; Choe, Heeman; Dunand, David C.

doi:10.1016/j.actamat.2017.09.066

Cited by 25 publications

(8 citation statements)

References 46 publications

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“…To do this, a finite element analysis (FEA) can be utilized to examine the mechanical stability, that is, calculate von Mises stresses of lamellar walls with small pores inside it. [43][44][45] The simulation revealed that the pore volume fraction and diameter in specific ranges have a slightly harmful effect on the mechanical stability, thus supporting the data measured from the experiment. This study provides effective TSS techniques that can boost the functionality and mechanical stability of a freeze-casted porous architecture.…”

Section: Introductionsupporting

confidence: 79%

“…The maximum stress was estimated by averaging the von Mises stress within 10% of the elements with the highest value as a criterion for measuring the mechanical stability of lamellar walls. 43,44 As the pore volume fraction increases, the spatial distribution of the pores becomes denser, thus leading to localized deformation and stress concentration in the narrow regions between pores close to one another. With the pore volume fraction of 1.45%, the maximum stress reaches 4.38 GPa under compressive engineering strain of 1%.…”

Section: Effect Of Pores On the Mechanical Strength Of Lamellar Wallsmentioning

confidence: 99%

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Simultaneous control of mechanical strength and hierarchical structure in freeze‐casted porous alumina by two‐step sintering

Jeon,

Woo,

Kim

et al. 2023

J Am Ceram Soc.

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To increase mechanical strength of porous ceramics, here, an effective Two‐Step Sintering (TSS) technique capable of producing highly porous alumina with enhanced mechanical strength is suggested. Based on the sintering theories, here, a significantly lower activation energy for densification at low temperature region allowed a beneficial temperature range for the TSS to be deduced. With a specific TSS regime (T1 = 1550°C and T2 = 1400°C), significantly higher compressive strength levels (8.00‐15.24 MPa) were measured with apparent porosity of 56.49% compared to conventional sintering (1.03‐1.86 MPa) with similar apparent porosity of 57.84%. Specifically, another TSS regime (T1 = 1550°C and T2 = 1380°C) left submicron‐sized open pores within the lamellar walls, providing a hierarchical porous structure with enhanced mechanical strength. An evaluation of the mechanical stability by a finite element analysis indicated outstanding compressive strength even with small pores in the lamella walls.This article is protected by copyright. All rights reserved

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Section: Introductionsupporting

confidence: 79%

Section: Effect Of Pores On the Mechanical Strength Of Lamellar Wallsmentioning

confidence: 99%

Simultaneous control of mechanical strength and hierarchical structure in freeze‐casted porous alumina by two‐step sintering

Jeon,

Woo,

Kim

et al. 2023

J Am Ceram Soc.

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“…Various investigations indicated that the microstructure of scaffolds, i.e., porosity, pore size and shape, and interconnectivity are the most essential criteria to support 3D cell growth, induce vascularization, and regenerate defective sites (Park et al, 2018a). Among a number of technologies proposed to fabricate scaffolds, 3D printing has been known as the most accurate technique that provides an opportunity to design scaffolds based on biomimicry, autonomous self-assembly, and the requirements of the target tissue.…”

Section: Morphology Observation and Surface Topographymentioning

confidence: 99%

Surface Functionalization of Three Dimensional-Printed Polycaprolactone-Bioactive Glass Scaffolds by Grafting GelMA Under UV Irradiation

et al. 2020

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In this study, bioactive glass nanoparticles (BGNPs) with an average diameter of less than 10 nm were synthesized using a sol-gel method and then characterized by transmission electron microscopy (TEM), differential scanning calorimetric (DSC), Fourier transforms infrared spectroscopy (FTIR), and x-ray spectroscopy (XRD). Afterward, three dimensional (3D)-printed polycaprolactone (PCL) scaffolds along with fused deposition modeling (FDM) were incorporated with BGNPs, and the surface of the composite constructs was then functionalized by coating with the gelatin methacryloyl (GelMA) under UV irradiation. Field emission scanning electron microscopy micrographs demonstrated the interconnected porous microstructure with an average pore diameter of 260 µm and homogeneous distribution of BGNPs. Therefore, no noticeable shrinkage was observed in 3D-printed scaffolds compared with the computer-designed file. Besides, the surface was uniformly covered by GelMA, and no effect of surface modification was observed on the microstructure while surface roughness increased. The addition of the BGNPs the to PCL scaffolds showed a slight change in pore size and porosity; however, it increased surface roughness. According to mechanical analysis, the compression strength of the scaffolds was increased by the BGNPs addition and surface modification. Also, a reduction was observed in the absorption capacity and biodegradation of scaffolds in phosphate-buffered saline media after the incorporation of BGNPs, while the presence of the GelMA layer increased the swelling potential and stability of the composite matrixes. Moreover, the capability of inducing bio-mineralization of hydroxyapatite-like layers, as a function of BGNPs content, was proven by FE-SEM micrographs, EDX spectra, and x-ray diffraction spectra (XRD) after soaking the obtained samples in concentrated simulated body fluid. A higher potential of the modified constructs to interact with the aqueous media led to better precipitation of minerals. According to in-vitro assays, the modified scaffolds can provide a suitable surface for the attachment and spreading of the bone marrow mesenchymal stem cells (BMSCs). Furthermore, the number of the proliferated cells confirms the biocompatibility of the scaffolds, especially after a modification process. Cell differentiation was verified by alkaline phosphatase activity as well as the expression of osteogenic genes such as osteocalcin and osteopontin. Accordingly, the scaffolds showed an initial potential for reconstruction of the injured bone.

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“…as preforms [50,51]. However, such strategies may have several limitations compared to the direct templating of final products.…”

Section: Processingmentioning

confidence: 99%

Ice-templated porous tungsten and tungsten carbide inspired by natural wood

Zhou

Tan

Jiao

et al. 2020

Journal of Materials Science & Technology

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The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications. However, it is challenging to construct and control the architectures by means of self-assembly in W/WC systems because of their large densities. Here we present the development of unidirectionally porous architectures, with high porosities exceeding 65 vol.%, for W and WC scaffolds which in many respects reproduce the design motif of natural wood using a direct ice-templating technique. This was achieved by adjusting the viscosities of suspensions to retard sedimentation during freezing. The processing, structural characteristics and mechanical properties of the resulting scaffolds were investigated with the correlations between them explored. Quantitative relationships were established to describe their strengths based on the mechanics of cellular solids by taking into account both inter-and intra-lamellar pores. The fracture mechanisms were also identified, especially in light of the porosity. This study extends the effectiveness of the ice-templating technique for systems with large densities or particle sizes. It further provides preforms for developing new nature-inspired multifunctional materials, as represented by W/WC-Cu composites.

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Surface-oxidized, freeze-cast cobalt foams: Microstructure, mechanical properties and electrochemical performance

Cited by 25 publications

References 46 publications

Simultaneous control of mechanical strength and hierarchical structure in freeze‐casted porous alumina by two‐step sintering

Simultaneous control of mechanical strength and hierarchical structure in freeze‐casted porous alumina by two‐step sintering

Surface Functionalization of Three Dimensional-Printed Polycaprolactone-Bioactive Glass Scaffolds by Grafting GelMA Under UV Irradiation

Ice-templated porous tungsten and tungsten carbide inspired by natural wood

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