| 1. |
- Cui, Luqing, et al.
(författare)
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Cyclic Response of Additive Manufactured 316L Stainless Steel : The Role of Cell Structures
- 2021
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Ingår i: Scripta Materialia. - : Elsevier. - 1359-6462 .- 1872-8456. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- We report the effect of cell structures on the fatigue behavior of additively manufactured (AM) 316L stainless steel (316LSS). Compared with the cell-free samples, the fatigue process of fully cellular samples only consists of steady and overload stages, without an initial softening stage. Moreover, the fully cellular sample possesses higher strength, lower cyclic softening rate and longer lifetime. Microscopic analyses show no difference in grain orientations, dimensions, and shapes. However, the fully cellular samples show planar dislocation structures, whereas the cell-free samples display wavy dislocation structures. The existence of cell structures promotes the activation of planar slip, delays strain localization, and ultimately enhances the fatigue performance of AM 316LSS.
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| 2. |
- Cui, Luqing, et al.
(författare)
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Superior low cycle fatigue property from cell structures in additively manufactured 316L stainless steel
- 2022
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Ingår i: Journal of Materials Science & Technology. - Amsterdam, Netherlands : Elsevier. - 1005-0302. ; 111, s. 268-278
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the low cycle fatigue (LCF) properties and the extent of strengthening in a dense additively manufactured stainless steel containing different volume fractions of cell structures but having all other microstructure characteristics the same. The samples were produced by laser powder bed fusion (L-PBF), and the concentration of cell structures was varied systematically by varying the annealing treatments. Load-controlled fatigue experiments performed on samples with a high fraction of cell structures reveal an up to 23 times increase in fatigue life compared to an essentially cell-free sample of the same grain configuration. Multiscale electron microscopy characterizations reveal that the cell structures serve as the soft barriers to the dislocation propagation and the partials are the main carrier for cyclic loading. The cell structures, stabilized by the segregated atoms and misorientation between the adjacent cells, are retained during the entire plastic deformation, hence, can continuously interact with dislocations, promote the formation of nanotwins, and provide massive 3D network obstacles to the dislocation motion. The compositional micro-segregation caused by the cellular solidification features serves as another non-negligible strengthening mechanism to dislocation motion. Specifically, the cell structures with a high density of dislocation debris also appear to act as dislocation nucleation sites, very much like coherent twin boundaries. This work indicates the potential of additive manufacturing to design energy absorbent alloys with high performance by tailoring the microstructure through the printing process.
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| 3. |
- Mo, Lixin, et al.
(författare)
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Nano-Silver Ink of High Conductivity and Low Sintering Temperature for Paper Electronics
- 2019
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Ingår i: Nanoscale Research Letters. - : Springer New York LLC. - 1931-7573 .- 1556-276X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Highly conductive ink with low sintering temperature is important for printed electronics on paper substrate. Silver nanoparticles (Ag NPs) of different average radii ranging from 48 to 176 nm were synthesized by adjusting the Ag+ concentration in the reaction process. The electric resistivity of the Ag NP-based ink film in relation to Ag NP size, sintering temperature, amount of PVP capping agent on Ag NP surface, and morphology evolution of the film during heating process was investigated. It was found that the resistivity of the films reduced very rapidly with increasing particle size due above all to reduced amount of protective agent capping on the Ag NPs. A semi-empirical relationship between the resistivity and the particle size was proposed. With the help of this mathematical expression, one gains both systematic and detailed insight to the resistivity evaluation with regard to the Ag particle size. The optimal electric resistivity of 4.6 μΩ cm was achieved at 140 °C for 10 min which was very close to the resistivity value of bulk Ag (1.58 μΩ cm). Mechanical flexibility of the printed electronics with the Ag NP-based ink on paper substrates was investigated. The prints on the art coated paper exhibited better flexibility compared to that on the photopaper. This might be attributed to the surface coating composition, surface morphology of the paper, and their corresponding ink absorption property. © 2019, The Author(s).
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| 4. |
- Mo, Lixin, et al.
(författare)
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Silver Nanoparticles Based Ink with Moderate Sintering in Flexible and Printed Electronics
- 2019
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 20:9
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Tidskriftsartikel (refereegranskat)abstract
- Printed electronics on flexible substrates has attracted tremendous research interest research thanks its low cost, large area production capability and environmentally friendly advantages. Optimal characteristics of silver nanoparticles (Ag NPs) based inks are crucial for ink rheology, printing, post-print treatment, and performance of the printed electronics devices. In this review, the methods and mechanisms for obtaining Ag NPs based inks that are highly conductive under moderate sintering conditions are summarized. These characteristics are particularly important when printed on temperature sensitive substrates that cannot withstand sintering of high temperature. Strategies to tailor the protective agents capping on the surface of Ag NPs, in order to optimize the sizes and shapes of Ag NPs as well as to modify the substrate surface, are presented. Different (emerging) sintering technologies are also discussed, including photonic sintering, electrical sintering, plasma sintering, microwave sintering, etc. Finally, applications of the Ag NPs based ink in transparent conductive film (TCF), thin film transistor (TFT), biosensor, radio frequency identification (RFID) antenna, stretchable electronics and their perspectives on flexible and printed electronics are presented.
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| 5. |
- Xin, Zhiqing, et al.
(författare)
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Surface energy guided patterning for printed electronics applications
- 2018
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Ingår i: 45th International IARIGAI conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We demonstrated patterning method for silver nanoparticle ink by wire-wound rod coating on commercial paper substrate. The hydrophobic and hydrophilic zones (patterns) on the paper surface were created by combining coating of hydrophobic dispersion with selective plasma treatment using a mask. Thanks to the surface energy difference in different zones, the silver nanoparticle ink self-aligned to form desired patterns, e.g. a matrix of lines of 0.5 mm wide with 0.3 mm spacing.
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