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Xue S, Li Phuah X, Jian J, Li Q, Li J, Yang B, Zhang D, Wang H, Tsakalakos T, Mukherjee AK, Wang H, Zhang X. In situ studies on defect formation dynamics in flash-sintered TiO 2. NANOSCALE 2023; 15:16752-16765. [PMID: 37817681 DOI: 10.1039/d3nr02630b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Flash-sintered (FS) ceramics have shown promising mechanical deformability at room temperature compared to conventional sintered ceramics. One major contributing factor to plasticity is high-density defects, such as dislocations, stacking faults and point defects, resulted presumably from the high electrical field during flash sintering. However, such direct experiemtnal evidence for defect formation and evolution under the electric field remains lacking. Here we performed in situ biasing experiments in FS and conventionally sintered (CS) polycrystalline TiO2 in a transmission electron microscope (TEM) to compare the defect evolution dynamics. In situ TEM studies revealed the coalescence of point defects under the electrical field in both FS and CS TiO2 and the subsequent formation of stacking faults, which are often referred to as Wadsley defects. Surprisingly, under the electrical field, the average fault growth rate in the FS samples is 10 times as much as that in the CS TiO2. Furthermore, the Magnéli phase, a 3D oxygen-deficient phase formed by the aggregation of Wadsley defects, is observed in the FS samples, but not in the CS samples. The present study provides new insights into defect dynamics in FS ceramics.
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Affiliation(s)
- Sichuang Xue
- StateKey Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Xin Li Phuah
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Jie Jian
- Institute of Special Environments Physical Sciences, Harbin Institute of Technology, Shenzhen, 518055, P.R. China
| | - Qiang Li
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Jin Li
- Institute of Special Environments Physical Sciences, Harbin Institute of Technology, Shenzhen, 518055, P.R. China
| | - Bo Yang
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Di Zhang
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Han Wang
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Thomas Tsakalakos
- Department of Materials Science and Engineering, Rutgers University, New Brunswick, NJ 08901, USA
| | - Amiya K Mukherjee
- Department of Materials Science and Engineering, University of California, Davis, CA 95616, USA
| | - Haiyan Wang
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
- School of Electrical and Computer Engineering, West Lafayette, IN 47907, USA.
| | - Xinghang Zhang
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA.
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Wang K, Zu Y, Chen G, Fu X, Zhou W. Effects of an Electric Current on the Superplastic Deformation Behavior of 3Y-TZP in an Oxygen-Lean Atmosphere. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6785. [PMID: 37895765 PMCID: PMC10607986 DOI: 10.3390/ma16206785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/15/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023]
Abstract
The aim of this paper is to investigate the mechanism of an electric current-assisted superplastic deformation on 3Y-TZP in an oxygen-lean atmosphere. The experiments were performed with different electric currents in the range of 0~5 A. The results show that the flow stress of 3Y-TZP during the deformation was significantly decreased by the combination of Joule heating and the applied current effect. The microstructures of the deformed specimens were all equiaxed grains without an obvious preferential grain growth. The stress exponent n = 2.05~2.61 suggested that the dominant deformation of 3Y-YZP with/without the electric current was grain boundary sliding at 1400 °C. The activation energy of the deformation which decreased from 465 kJ mol-1 to 315 kJ mol-1 by the electric current indicated that the lattice diffusion of Zr cation during the deformation was enhanced. And the deformation rate of 3Y-TZP with the electric current may be controlled by the grain boundary diffusion of Zr cation.
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Affiliation(s)
- Kang Wang
- Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Technology, Dalian University of Technology, Dalian 116085, China; (K.W.); (X.F.); (W.Z.)
| | - Yufei Zu
- Key Laboratory of Advanced Technology for Aerospace Vehicles (Liaoning Province), School of Aeronautics and Astronautics, Dalian University of Technology, Dalian 116085, China;
| | - Guoqing Chen
- Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Technology, Dalian University of Technology, Dalian 116085, China; (K.W.); (X.F.); (W.Z.)
| | - Xuesong Fu
- Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Technology, Dalian University of Technology, Dalian 116085, China; (K.W.); (X.F.); (W.Z.)
| | - Wenlong Zhou
- Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Technology, Dalian University of Technology, Dalian 116085, China; (K.W.); (X.F.); (W.Z.)
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Nambu K, Morita K, Soga K, Yamamoto T, Masuda H, Yoshida H. Densification of Y2O3 by flash sintering under an AC electric field. Ann Ital Chir 2022. [DOI: 10.1016/j.jeurceramsoc.2021.10.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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Flash Sintering Research Perspective: A Bibliometric Analysis. MATERIALS 2022; 15:ma15020416. [PMID: 35057139 PMCID: PMC8779415 DOI: 10.3390/ma15020416] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/20/2021] [Accepted: 01/02/2022] [Indexed: 02/03/2023]
Abstract
Flash Sintering (FS), a relatively new Field-Assisted Sintering Technique (FAST) for ceramic processing, was proposed for the first time in 2010 by Prof. Rishi Raj’s group from the University of Colorado at Boulder. It quickly grabbed the attention of the scientific community and since then, the field has rapidly evolved, constituting a true milestone in materials processing with the number of publications growing year by year. Moreover, nowadays, there is already a scientific community devoted to FS. In this work, a general picture of the scientific landscape of FS is drawn by bibliometric analysis. The target sources, the most relevant documents, hot and trending topics as well as the social networking of FS are unveiled. A separate bibliometric analysis is also provided for Reaction or Reactive Flash Sintering (RFS), where not only the sintering, but also the synthesis is merged into a single step. To the best of our knowledge, this is the first study of this nature carried out in this field of research and it can constitute a useful tool for researchers to be quickly updated with FS as well as to strategize future research and publishing approaches.
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Manière C, Harnois C, Riquet G, Lecourt J, Bilot C, Marinel S. Flash spark plasma sintering of zirconia nanoparticles: Electro-thermal-mechanical-microstructural simulation and scalability solutions. Ann Ital Chir 2022. [DOI: 10.1016/j.jeurceramsoc.2021.09.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Deng H, Biesuz M, Vilémová M, Kermani M, Veverka J, Tyrpekl V, Hu C, Grasso S. Ultrahigh Temperature Flash Sintering of Binder-Less Tungsten Carbide within 6 s. MATERIALS 2021; 14:ma14247655. [PMID: 34947253 PMCID: PMC8703299 DOI: 10.3390/ma14247655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/03/2021] [Accepted: 12/07/2021] [Indexed: 11/17/2022]
Abstract
We report on an ultrarapid (6 s) consolidation of binder-less WC using a novel Ultrahigh temperature Flash Sintering (UFS) approach. The UFS technique bridges the gap between electric resistance sintering (≪1 s) and flash spark plasma sintering (20–60 s). Compared to the well-established spark plasma sintering, the proposed approach results in improved energy efficiency with massive energy and time savings while maintaining a comparable relative density (94.6%) and Vickers hardness of 2124 HV. The novelty of this work relies on (i) multiple steps current discharge profile to suit the rapid change of electrical conductivity experienced by the sintering powder, (ii) upgraded low thermal inertia CFC dies and (iii) ultra-high consolidation temperature approaching 2750 °C. Compared to SPS process, the UFS process is highly energy efficient (≈200 times faster and it consumes ≈95% less energy) and it holds the promise of energy efficient and ultrafast consolidation of several conductive refractory compounds.
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Affiliation(s)
- Huaijiu Deng
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (H.D.); (M.K.); (C.H.)
| | - Mattia Biesuz
- Institute of Plasma Physics of the Czech Academy of Sciences, Za Slovankou 3, 182 00 Prague, Czech Republic; (M.B.); (M.V.); (J.V.)
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic;
| | - Monika Vilémová
- Institute of Plasma Physics of the Czech Academy of Sciences, Za Slovankou 3, 182 00 Prague, Czech Republic; (M.B.); (M.V.); (J.V.)
| | - Milad Kermani
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (H.D.); (M.K.); (C.H.)
| | - Jakub Veverka
- Institute of Plasma Physics of the Czech Academy of Sciences, Za Slovankou 3, 182 00 Prague, Czech Republic; (M.B.); (M.V.); (J.V.)
| | - Václav Tyrpekl
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic;
| | - Chunfeng Hu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (H.D.); (M.K.); (C.H.)
| | - Salvatore Grasso
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (H.D.); (M.K.); (C.H.)
- Correspondence: ; Tel.: +86-184-8222-4962
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Hwang C, Yun J. Effect of Processing Conditions on the Flash Onset Temperature in Hydroxyapatite. MATERIALS 2021; 14:ma14185229. [PMID: 34576453 PMCID: PMC8469700 DOI: 10.3390/ma14185229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/06/2021] [Accepted: 09/08/2021] [Indexed: 11/16/2022]
Abstract
When heat and electric field are applied to the sample, sintering takes place within a short time of a few seconds by the flash phenomenon that occurs. In what condition flash does occur is a main issue for the flash sintering technique. In this study, the effect of processing conditions such as sintering atmosphere, sample size, density and grain size on the flash onset of hydroxyapatite was investigated. In a vacuum atmosphere, a flash occurred at a lower temperature by 50–100 °C than in air. The smaller the thickness of the sample, the higher the flash onset temperature due to the larger specific surface area. Flash was also observed in samples which were presintered, having a density of 86–100% and a grain size of 0.2–0.9 μm. When the density and grain size of the sample were higher and larger, the flash onset temperature was higher. It was because the diffusion and conduction path through the grain boundary and the inner surface of the pores with high defect concentration are blocked with an increase of density or grain size. When an electric field was applied during flash sintering, a color change of the sample was observed and the reason was discussed.
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Affiliation(s)
- Changhun Hwang
- Department of Advanced Engineering, Graduate School, Kyungnam University, Changwon 51767, Korea;
| | - Jondo Yun
- Department of Advanced Materials Engineering, Kyungnam University, Changwon 51767, Korea
- Correspondence:
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Avila V, Yoon B, Ghose S, Raj R, Jesus LM. Phase evolution during reactive flash sintering of Li6.25Al0.25La3Zr2O12 starting from a chemically prepared powder. Ann Ital Chir 2021. [DOI: 10.1016/j.jeurceramsoc.2021.02.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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9
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Luo N, Lin Y, Guo J, Quattrocchi E, Deng H, Dong J, Ciucci F, Boi F, Hu C, Grasso S. Spark Plasma Sintering of LiFePO 4: AC Field Suppressing Lithium Migration. MATERIALS 2021; 14:ma14112826. [PMID: 34070590 PMCID: PMC8198947 DOI: 10.3390/ma14112826] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 05/21/2021] [Indexed: 11/16/2022]
Abstract
Our work proposes a comparison between Spark Plasma Sintering of LiFePO4 carried out using an Alternating Current (AC) and Direct Current (DC). It quantifies the Li-ion migration using DC, and it validates such hypothesis using impedance spectroscopy, X-ray photoelectron spectroscopy and inductively coupled plasma optical emission spectroscopy. The use of an AC field seems effective to inhibit undesired Li-ion migration and achieve high ionic conductivity as high as 4.5 × 10−3 S/cm, which exceeds by one order of magnitude samples processed under a DC field. These results anticipate the possibility of fabricating a high-performance all-solid-state Li-ion battery by preventing undesired Li loss during SPS processing.
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Affiliation(s)
- Nan Luo
- Key Laboratory of Advanced technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (N.L.); (Y.L.); (H.D.); (J.D.); (C.H.)
| | - Yong Lin
- Key Laboratory of Advanced technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (N.L.); (Y.L.); (H.D.); (J.D.); (C.H.)
| | - Jian Guo
- College of Physics, Sichuan University, Chengdu 610064, China; (J.G.); (F.B.)
| | - Emanuele Quattrocchi
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China; (E.Q.); (F.C.)
| | - Huaijiu Deng
- Key Laboratory of Advanced technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (N.L.); (Y.L.); (H.D.); (J.D.); (C.H.)
| | - Jian Dong
- Key Laboratory of Advanced technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (N.L.); (Y.L.); (H.D.); (J.D.); (C.H.)
| | - Francesco Ciucci
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China; (E.Q.); (F.C.)
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Filippo Boi
- College of Physics, Sichuan University, Chengdu 610064, China; (J.G.); (F.B.)
| | - Chunfeng Hu
- Key Laboratory of Advanced technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (N.L.); (Y.L.); (H.D.); (J.D.); (C.H.)
| | - Salvatore Grasso
- Key Laboratory of Advanced technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; (N.L.); (Y.L.); (H.D.); (J.D.); (C.H.)
- Correspondence: ; Tel.: +183-2867-6558
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11
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A thermal perspective of flash sintering: The effect of AC current ramp rate on microstructure evolution. Ann Ital Chir 2021. [DOI: 10.1016/j.jeurceramsoc.2020.11.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Phuah XL, Cho J, Dou L, Rheinheimer W, García RE, Zhang X, Wang H. Field-assisted growth of one-dimensional ZnO nanostructures with high defect density. NANOTECHNOLOGY 2021; 32:095603. [PMID: 33202392 DOI: 10.1088/1361-6528/abcb2f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
One-dimensional ZnO nanostructures have shown great potential in electronics, optoelectronics and electromechanical devices owing to their unique physical and chemical properties. Most of these nanostructures were grown by equilibrium processes where the defects density is controlled by thermodynamic equilibrium. In this work, flash sintering, a non-equilibrium field-assisted processing method, has been used to synthesize ZnO nanostructures. By applying a high electric field and limiting a low current flow, ZnO nanorods grew uniformly by a vapor-liquid-solid mechanism due to the extreme temperatures achieved near the hot spot. High density basal stacking faults in the nanorods along with ultraviolet excitonic emission and a red emission under room temperature demonstrate the potential of defect engineering in nanostructures via the field-assisted growth method.
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Affiliation(s)
- Xin Li Phuah
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, United States of America
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13
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Flash Sintering of YSZ/Al 2O 3 Composites: Effect of Processing and Testing Conditions. MATERIALS 2021; 14:ma14041031. [PMID: 33671657 PMCID: PMC7926826 DOI: 10.3390/ma14041031] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/04/2021] [Accepted: 02/17/2021] [Indexed: 11/17/2022]
Abstract
The flash sintering behavior of yttria-stabilized zirconia/alumina composites was investigated to understand the role of the fundamental processing and testing parameters (electric field intensity, electric current limit, thermal insulation, homogeneity and dispersion of the two phases) on densification. A strong relation between the composite compositions and the electric parameters needed to promote flash sintering is revealed. Interestingly, the composite preparation method, which affects the two-phases dispersion homogeneity, was shown to have a relevant effect on the flash onset conditions, where the more homogeneous material is more difficult to be flashed. Moreover, the use of a simple thermal insulation system around the green body allowed to improve the final density of the composites under constant electric current.
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15
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Tekin YH, Hayran Y. Fracture resistance and marginal fit of the zirconia crowns with varied occlusal thickness. J Adv Prosthodont 2020; 12:283-290. [PMID: 33149849 PMCID: PMC7604235 DOI: 10.4047/jap.2020.12.5.283] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/26/2020] [Accepted: 08/13/2020] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The present study aimed to evaluate the clinical applicability of monolithic zirconia (MZ) crowns of different thickness via determination of fracture resistance and marginal fit. MATERIALS AND METHODS MZ crowns with 0.5, 0.8, 1.0, and 1.5 mm thickness and porcelain fused to metal (PFM) crowns were prepared, ten crowns in each group. Marginal gaps of the crowns were measured. All crowns were aged with thermal cycling (5 - 55℃/10000 cycle) and chewing simulator (50 N/1 Hz/lateral movement: 2 mm, mouth opening: 2 mm/240000 cycles). After aging, fracture resistance of crowns was determined. Statistical analysis was performed with one-way ANOVA and Tukey's HDS post hoc test. RESULTS Fracture loads were higher in the PFM and 1 mm MZ crowns compared to 0.5 mm and 0.8 mm crowns. 1.5 mm MZ crowns were not broken even with the highest force applied (10 kN). All marginal gap values were below 86 µm even in the PFM crowns, and PFM crowns had a higher marginal gap than the MZ crowns. CONCLUSION The monolithic zirconia exhibited high fracture resistance and good marginal fit even with the 0.5 mm thickness, which might be used with reduced occlusal thickness and be beneficial in challengingly narrow interocclusal space.
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Affiliation(s)
- Yadel Hazır Tekin
- Department of Prosthodontic Dentistry, Faculty of Dentistry, Tokat Gaziosmanpasa University, Tokat, Turkey
| | - Yeliz Hayran
- Department of Prosthodontic Dentistry, Faculty of Dentistry, Tokat Gaziosmanpasa University, Tokat, Turkey
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Biesuz M, Saunders TG, Chen K, Bortolotti M, Salvo M, Grasso S, Reece MJ. Interfacial reaction between ZrNbHfTa foil and graphite: Formation of high-entropy carbide and the effect of heating rate on its microstructure. Ann Ital Chir 2020. [DOI: 10.1016/j.jeurceramsoc.2019.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Current-ramp assisted sintering of 3YSZ: Electrochemical and microstructural comparison to flash and thermal sintering. Ann Ital Chir 2020. [DOI: 10.1016/j.jeurceramsoc.2019.09.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Gorynski C, Anselmi-Tamburini U, Winterer M. Controlling current flow in sintering: A facile method coupling flash with spark plasma sintering. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:015112. [PMID: 32012646 DOI: 10.1063/1.5119059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 12/25/2019] [Indexed: 06/10/2023]
Abstract
A facile method is described to couple flash sintering (FS) and spark plasma sintering (SPS). Flash spark plasma sintering (FSPS) combines advantages of both techniques: the use of pellet-shaped samples under mechanical load with the controlled passage of electric current through the sample. FSPS is realized by partially replacing graphite pressing tools (two punches and one matrix) used in standard SPS. An insulating boron nitride matrix substitutes the conducting graphite matrix to force the electric current through the sample. Additionally, external heating of the boron nitride matrix is implemented. Microstructures of standard and flash-SPS are compared using aluminum doped zinc oxide as an example. Scanning electron microscopy reveals that different microstructures are generated for SPS and FSPS. The new setups provide novel processing routes for different current sintering methods of materials under mechanical load and assist in identifying the role of the electric current or field in the microstructure.
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Affiliation(s)
- C Gorynski
- Nanoparticle Process Technology, Department of Mechanical Engineering and CENIDE, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
| | - U Anselmi-Tamburini
- Department of Chemistry, University of Pavia, Via Torquato Taramelli 12, 27100 Pavia, Italy
| | - M Winterer
- Nanoparticle Process Technology, Department of Mechanical Engineering and CENIDE, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
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De Souza RA, Dickey EC. The effect of space-charge formation on the grain-boundary energy of an ionic solid. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20180430. [PMID: 31280710 PMCID: PMC6635631 DOI: 10.1098/rsta.2018.0430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
Taking the model system of an oxide containing acceptor dopant cations and charge-compensating oxygen vacancies, we calculate at the continuum level the change in the excess grain-boundary energy of an ionic solid upon space-charge formation. Two different cases are considered for the space-charge layers: (i) only vacancies attain electrochemical equilibrium and (ii) both dopants and vacancies attain electrochemical equilibrium. The changes calculated for a specific set of grain boundaries indicate that, depending on dopant concentration, space-charge formation can decrease the excess free energy by up to 15% in the first case and by up to 45% in the second case. The possibility of the excess grain-boundary energy going to zero and the possible effects of an external electric field on the excess grain-boundary energy are also discussed. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.
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Affiliation(s)
- R. A. De Souza
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - E. C. Dickey
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907, USA
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Biesuz M, Sedlák R, Saunders T, Kovalčíková A, Dusza J, Reece M, Zhu D, Hu C, Grasso S. Flash spark plasma sintering of 3YSZ. Ann Ital Chir 2019. [DOI: 10.1016/j.jeurceramsoc.2019.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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22
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Development of highly inhomogeneous temperature profile within electrically heated alkali silicate glasses. Sci Rep 2019; 9:2805. [PMID: 30808914 PMCID: PMC6391379 DOI: 10.1038/s41598-019-39431-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 01/22/2019] [Indexed: 11/09/2022] Open
Abstract
According to Joule's well-known first law, application of electric field across a homogeneous solid should produce heat uniformly in proportion to the square of electrical current. Here we report strong departure from this expectation for common, homogeneous ionic solids such as alkali silicate glasses when subjected even to moderate fields (~100 V/cm). Unlike electronically conducting metals and semiconductors, with time the heating of ionically conducting glass becomes extremely inhomogeneous with the formation of a nanoscale alkali-depletion region, such that the glass melts near the anode, even evaporates, while remaining solid elsewhere. In situ infrared imaging shows and finite element analysis confirms localized temperatures more than thousand degrees above the remaining sample depending on whether the field is DC or AC. These observations unravel the origin of recently discovered electric field induced softening of glass. The observed highly inhomogeneous temperature profile point to the challenges for the application of Joule's law to the electrical performance of glassy thin films, nanoscale devices, and similarly-scaled phenomena.
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Abstract
In this work, powders of cemented ultrafine WC-6 wt.% Co were consolidated. The feasibility of the medium frequency electrical resistance sintering (MF-ERS) technique were studied to prevent WC grain growth during consolidation. Porosity and hardness were measured at different zones of the MF-ERS compacts. The compacts showed a slight inhomogeneity in their properties across their section, but it was controlled by choosing suitable values of the processing parameters. The optimal values for the material studied were current intensities between 7 and 8 kA and sintering times between 600 and 800 ms. The main achievement using this consolidation method was that sintered compacts essentially maintained the initial WC grain size. This was attained to processing times of less than 2 s, and without the need for using protective atmospheres.
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