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Homogeneous Dispersion of Yttrium Oxide Particles in Nickel-Based Superalloy by High Pressure Homogenizing and Ball Milling Method

Jongmin Byun Young-In Lee Sung-Tag Oh
Archives of Metallurgy and Materials | 2021 | vol. 66 | No 4 | 1055-1058 | DOI: 10.24425/amm.2021.136424
Keywords Ni-based superalloy Y2O3 dispersion High pressure homogenizer spark plasma sintering microstructure
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Abstract

An optimum route to fabricate the Ni-based superalloy with homogeneous dispersion of Y2O3 particles is investigated. Ni-based ODS powder was prepared by high-energy ball milling of gas-atomized alloy powders and Y2O3 particles treated with a high-pressure homogenizer. Decrease in particle size and improvement of dispersion stability were observed by high-pressure homogenization of as-received Y2O3 particles, presumably by the powerful cavitation forces and by collisions of the particles. Microstructural analysis for the ball-milled powder mixtures reveal that Ni-based ODS powders prepared from high-pressure homogenization of Y2O3 particles exhibited more fine and uniform distribution of Ni and Y elements compared to the as-received powder. These results suggested that high-pressure homogenization process is useful for producing Ni-based superalloy with homogeneously dispersed oxide particles.
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Bibliography

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[14] M. Luo, X. Qi, T. Ren, Y. Huang, A.A. Keller, H. Wang, B. Wu, H. Jin, F. Li, Colloids Surf. A 533, 9 (2017).
[15] C. Suryanarayana, Prog. Mater. Sci. 46, 1 (2001).
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Authors and Affiliations

Jongmin Byun
1
ORCID: ORCID
Young-In Lee
1
ORCID: ORCID
Sung-Tag Oh
1
ORCID: ORCID
  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering & The Institute of Powder Technology, Seoul 01811, Republic of Korea

Synthesis of Y2O3-Dispersed W Powders Prepared by Ultrasonic Spray Pyrolysis and Polymer Solution Route

Hyeonhui Jo Young-In Lee Myung-Jin Suk Young-Keun Jeong Sung-Tag Oh
Archives of Metallurgy and Materials | 2021 | vol. 66 | No 3 | 799-802 | DOI: 10.24425/amm.2021.136383
Keywords Tungsten Y2O3 dispersion Ultrasonic spray pyrolysis Wet chemical route
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Abstract

The nano-sized Y2O3 dispersed W composite powder is prepared by ultrasonic spray pyrolysis of a tungsten precursor using ammonium metatungstate hydrate and a polymer addition solution method using Y-nitrate. XRD analysis for calcined powder showed the formation of WO2 phase by partial oxidation of W powder during calcination in air. The TEM and phase analysis for further hydrogen reduction of calcined powder mixture exhibited that the W powder with a uniform distribution of Y2O3 nanoparticles can be successfully produced. These results indicate that the wet chemical method combined with spray pyrolysis and polymer solution is a promising way to synthesis the W-based composites with homogeneous dispersion of fine oxide particles.
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Bibliography

[1] W.D. Klopp, J. Less-Common Met. 42, 261 (1975).
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[9] S.C. Cifuentes, M.A. Monge, P. Pérez, Corros. Sci. 57, 114 (2012).
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Authors and Affiliations

Hyeonhui Jo
1
Young-In Lee
1 2
ORCID: ORCID
Myung-Jin Suk
3
Young-Keun Jeong
4
ORCID: ORCID
Sung-Tag Oh
1 2
ORCID: ORCID
  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul 01811, Republic of Korea
  2. Seoul National University of Science and Technology, The Institute of Powder Technology, Seoul 01811, Republic of Korea
  3. Kangwon National University, Department of Materials Science and Engineering, Samcheok 25913, Republic of Korea
  4. Pusan National University, Graduate School of Convergence Science, Busan 46241, Republic of Korea

Effect of Pyrolysis Conditions on the Physicochemical Properties of Graphitic Carbon Nitride for Visible-Light-Driven Photocatalytic Degradation

Jeong Hyun Kim Myeongjun Ji Cheol-Hui Ryu Young-In Lee
Archives of Metallurgy and Materials | 2020 | vol. 65 | No 3 | 1111-1116 | DOI: 10.24425/amm.2020.133226
Keywords g-C3N4 Pyrolysis Polymerization Synthesis condition Photocatalysis
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Abstract

Graphitic carbon nitride (g-C3N4) is an attractive photocatalyst, however, its practical photocatalytic applications are still faced with huge challenges. The aim of this research is to identify the correlation between synthetic conditions and properties of the g-C3N4 and derive an optimum synthesis condition for improving photocatalytic activities of the g-C3N4. In this study, novel and versatile g-C3N4 nanosheets were synthesized by the simple thermal pyrolysis of urea. In the synthesis process, the pyrolysis temperature and the heating rate, which can have the most significant influence on the structures and properties of g-C3N4, were set as variables, and the effects were systematically investigated. When synthesized at a relatively high temperature, the amount of material being synthesized is reduced, however it has been found to represent optical properties suitable for highly efficient photocatalyst by the increase in the thickness and defects formed in the g-C3N4 nanosheets. The photocatalytic degradation experiment of MB dyes indicated that the highest degradation of 95.2% after the reaction for 120 min was achieved on the g-C3N4 nanosheets synthesized at 650oC.

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Authors and Affiliations

Jeong Hyun Kim
ORCID: ORCID
Myeongjun Ji
ORCID: ORCID
Cheol-Hui Ryu
Young-In Lee
ORCID: ORCID

Dilatometric Analysis of the Sintering Behavior of Bi2Te3 Thermoelectric Powders

Ju-Yeon Han Jongmin Byun Young-In Lee Byung Joon Choi Hogyoung Kim Sung-Tag Oh
Archives of Metallurgy and Materials | 2020 | vol. 65 | No 3 | 1117-1120 | DOI: 10.24425/amm.2020.133227
Keywords Bi2Te3 Dilatometric analysis Sintering behavior Microstructure
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Abstract

The sintering behavior of p-type bismuth telluride powder is investigated by means of dilatometric analysis. The alloy powders, prepared by ball milling of melt-spun ribbons, exhibit refined and flake shape. Differential thermal analysis reveals that the endothermic peak at about 280oC corresponds to the melting of bismuth, and peaks existing between 410oC and 510oC are presumably due to the oxidation and crystallization of the powder. The shrinkage behavior of ball-milled powders was strongly dependent of heating rate by the thermal effect exerted on specimens. In the case of 2oC/min, the peak temperature for the densification is measured at 406oC, while the peak temperature at a heating rate of 20oC/min is approximately 443oC. The relative density of specimen pressureless-sintered at 500oC exhibited relatively low value, and thus further study is required in order to increase the density of sintered body.

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Authors and Affiliations

Ju-Yeon Han
Jongmin Byun
ORCID: ORCID
Young-In Lee
ORCID: ORCID
Byung Joon Choi
ORCID: ORCID
Hogyoung Kim
Sung-Tag Oh
ORCID: ORCID

Morphology Control of One-Dimensional gallium nitride Nanostructures by Modulating the Crystallinity of Sacrificial gallium oxide Templates

Yun Taek Ko Mijeong Park Jingyeong Park Jaeyun Moon Yong-Ho Choa Young-In Lee
Archives of Metallurgy and Materials | 2021 | vol. 66 | No 3 | 709-712 | DOI: 10.24425/amm.2021.136366
Keywords GaN Nanofiber Nanotube electrospinning chemical transformation
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Abstract

In this study, we demonstrated a method of controllably synthesizing one-dimensional nanostructures having a dense or a hollow structure using fibrous sacrificial templates with tunable crystallinity. The fibrous Ga2O3 templates were prepared by calcining the polymer/gallium precursor nanofiber synthesized by an electrospinning process, and their crystallinity was varied by controlling the calcination temperature from 500oC to 900oC. GaN nanostructures were transformed by nitriding the Ga2O3 nanofibers using NH3 gas. All of the transformed GaN nanostructures maintained a one-dimensional structure well and exhibited a diameter of about 50 nm, but their morphology was clearly distinguished according to the crystallinity of the templates. When the templates having a relatively low crystallinity were used, the transformed GaN showed a hollow nanostructure, and as the crystallinity increased, GaN was converted into a denser nanostructure. This morphological difference can be explained as being caused by the difference in the diffusion rate of Ga depending on the crystallinity of Ga2O3 during the conversion from Ga2O3 to GaN. It is expected that this technique will make possible the tubular nanostructure synthesis of nitride functional nanomaterials.
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Bibliography

[1] X. Yia, P. Yang, Y. Sun, Y. Wu, B. Mayers, B. Gates, Y. Yin, F. Kim, H. Yan, Adv. Mater. 15, 353 (2003).
[2] L. Cao, J.S. White, J.-S. Park, J.A. Schuller, B.M. Clemens, M.L. Brongersma, Nat. Mater. 8, 643 (2009).
[3] C.M. Hangarter, Y.‐I. Lee, S.C. Hernandez, Y.‐H. Choa, N.V. Myung, Angew. Chem. Int. Ed. 49, 7081 (2010).
[4] W. Han, S. Fan, Q.Q. Li, Y.D. Hu, Science 277, 1287 (1997).
[5] J .C. Johnson, H.J. Choi, K.P. Knutsen, R.D. Schaller, P. Yang, R.J. Saykally, Nat. Mater. 1, 106 (2002).
[6] X. Zhang, Q. Liu, B. Liu, W. Yang, J. Li, P. Niu, X. Jiang, J. Mater. Chem. C 5, 4319 (2017).
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[8] F . Lu, L. Liu, J. Tian, Appl. Surf. Sci. 497, 143791 (2019).
[9] S.W. Eaton, A. Fu, A.B. Wong, C.-Z. Ning, P. Yang, Nat. Rev. Mater. 1, 16028 (2016).
[10] J . Xue, T. Wu, Y. Dai, Y. Xia, Chem. Rev. 119, 5298 (2019)
[11] G .-D. Lim, J.-H. Yoo, M. Ji, Y.-I. Lee, J. Alloys Compd. 806, 1060 (2019).
[12] J . Xue, J. Xie, W. Liu, Y. Xia, Acc. Chem. Res. 50, 1976 (2017).
[13] Y. Sun, B. Mayers, Y. Xia, Adv. Mater. 15, 641 (2003).
[14] F . Caruso, R. A. Caruso, H. Mohwald, Science 282, 1111 (1998).
[15] Y.-I. Lee, Mater. Chem. Phys. 180, 104 (2016).
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Authors and Affiliations

Yun Taek Ko
1
ORCID: ORCID
Mijeong Park
2
ORCID: ORCID
Jingyeong Park
1
ORCID: ORCID
Jaeyun Moon
3
ORCID: ORCID
Yong-Ho Choa
1
ORCID: ORCID
Young-In Lee
2
ORCID: ORCID
  1. Hanyang University, Dept. of Advanced Materials Science and Engineering, Ansan 15588, Republic of Korea
  2. Seoul National University of Science and Technology, Dept. of Materials Science and Engineering, Seoul 01811, Republic of Korea
  3. University of Nevada , Dept. of Mechanical Engineering, Las Vegas, 4505 S. Maryland PKWY Las Vegas, Nv 89154, United States

Facile Synthesis of Bumpy-Structured ZnO-ZnS Core-Shell Microspheres with Enhanced Photocatalytic Performance

Hee Yeon Jeon Mijeong Park Seungheon Han Dong Hoon Lee Young-In Lee
Archives of Metallurgy and Materials | 2024 | vol. 69 | No 1 | 91-94 | DOI: 10.24425/amm.2024.147792
Keywords ZnO ZnS core-shell chemical transformation photocatalyst
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Abstract

Zinc oxide is considered an outstanding photocatalyst candidate, but its low photo-corrosion resistance is a problem to be solved. In the ZnO-ZnS core-shell structure, ZnS acts as a protective layer for the ZnO core, and thus, it can enhance stability and long-term performance. The ZnO-ZnS core-shell structure is synthesized into various nanoscale morphologies with high specific surface areas to improve photocatalytic efficiency. However, they are easily agglomerated and are hard to separate from reaction media. In this study, micro-sized bumpy spheres of ZnO-ZnS core-shell structure were prepared via facile chemical transformation of as-prepared ZnO. After sulfurization of the ZnO template, it was confirmed through SEM, TEM, EDS, and XPS analysis that a uniform ZnS shell layer was formed without significant change in the initial ZnO morphology. The ZnO-ZnS core-shell microsphere has shown superior efficiency and stability in the photocatalytic degradation of Rhodamine B compared with pristine ZnO microspheres
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Authors and Affiliations

Hee Yeon Jeon
1
ORCID: ORCID
Mijeong Park
1
ORCID: ORCID
Seungheon Han
1
ORCID: ORCID
Dong Hoon Lee
1
ORCID: ORCID
Young-In Lee
2
ORCID: ORCID
  1. Seoul National University Of Science and Technology, Department Of Materials Science and Engineering, Seoul 01811, Republic Of Korea
  2. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul 01811, Republic of Korea

Simple synthesis of Black TiO 2 Nanofibers Via Calcination in Inert Atmosphere

Myeongjun Ji Eung Ryong Kim Mi-Jeong Park Hee Yeon Jeon Jaeyun Moon Jongmin Byun Young-In Lee
Archives of Metallurgy and Materials | 2022 | vol. 67 | No 4 | 1481-1486 | DOI: 10.24425/amm.2022.141078
Keywords Black TiO2 nanofibers electrospinning calcination atmosphere
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Abstract

Black TiO 2nanofibers have recently emerged as a promising material that has both advantages of black metal oxide and one-dimensional nanostructure. However, current reduction-based synthesis approaches are not compatible with practical applications because these processes require high process costs, complicated processes, and sophisticated control. Therefore, it is still necessary to develop a simple and facile method that can easily introduce atomic defects during the synthesis process. This work suggests an electrospinning process with an antioxidant and subsequent calcination process for the facile synthesis of black TiO 2 nanofibers. The synthesized black TiO 2 nanofiber has an average diameter of 50.3 nm and a rutile structure. Moreover, this nanofiber represented a noticeable black color and a bandgap of 2.67 eV, clearly demonstrating the bandgap narrowing by the introduced atomic defects.
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Authors and Affiliations

Myeongjun Ji
1
ORCID: ORCID
Eung Ryong Kim
1
ORCID: ORCID
Mi-Jeong Park
1
ORCID: ORCID
Hee Yeon Jeon
1
ORCID: ORCID
Jaeyun Moon
2
ORCID: ORCID
Jongmin Byun
1
ORCID: ORCID
Young-In Lee
1
ORCID: ORCID
  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul, 01811, Republic of Korea
  2. University of Nevada, Department of Mechanical Engineering, Las Vegas, 4505 S. Maryland PKWY Las Vegas, NV 89154, United States

Synthesis and Characterization of W Composite Powder with La 2O 3-Y 2O 3 Nano-Dispersoids by Ultrasonic Spray Pyrolysis

Youn Ji Heo Eui Seon Lee Jeong Hyun Kim Young-In Lee Young-Keun Jeong Sung-Tag Oh
Archives of Metallurgy and Materials | 2022 | vol. 67 | No 4 | 1507-1510 | DOI: 10.24425/amm.2022.141083
Keywords W composite powder La2O3-Y2O3 dispersion Ultrasonic spray pyrolysis Polymeric additive solution method
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Abstract

An optimum route to synthesis the W-based composite powders with homogeneous dispersion of oxide nanoparticles was investigated. The La2O3 dispersed W powder was synthesized by ultrasonic spray pyrolysis using ammonium metatungstate hydrate and lanthanum nitrate. The dispersion of Y2O3 nanoparticles in W- La2O3 powder was carried out by a polymer addition solution method using yttrium nitrate. XPS and TEM analyses for the composite powder showed that the nano-sized La2O3 and Y2O3 particles were well distributed in W powder. This study suggests that the combination processing of ultrasonic spray pyrolysis and polymeric additive solution is a promising way to synthesis W-based composite powders.
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Authors and Affiliations

Youn Ji Heo
1 2
ORCID: ORCID
Eui Seon Lee
1
ORCID: ORCID
Jeong Hyun Kim
1
ORCID: ORCID
Young-In Lee
1 2
ORCID: ORCID
Young-Keun Jeong
3
ORCID: ORCID
Sung-Tag Oh
1 2
ORCID: ORCID
  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul 01811, Republic of Korea
  2. Seoul National University of Science and Technology, The Institute of Powder Technology, Seoul 01811, Republic of Korea
  3. Pusan National University, Graduate School of Convergence Science, Busan 46241, Republic of Korea

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