Ju-hyeon Yu - Academia.edu (original) (raw)
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CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)
Centre National de la Recherche Scientifique / French National Centre for Scientific Research
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Papers by Ju-hyeon Yu
Journal of Nuclear Materials
Nuclear Materials and Energy, 2022
Fusion Engineering and Design, 2016
Abstract SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate materi... more Abstract SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate material for the first-wall, components in the blanket and divertor of fusion reactors in future. In such components, SiC/SiC composites need to be formed to be various shapes. SiC/SiC tubes has been expected to be employed for blanket and divertor after DEMO reactor, but there is not established mechanical investigation technique. Recent progress of SiC/SiC processing techniques is likely to realize strong, having gas tightness SiC/SiC tubes which will contribute for the development of fusion reactors. This research studies the relationship between deformation and strain of SiC/SiC tube using a circumferential tensile test method to establish a mechanical property investigation method of SiC/SiC tubes.
Fusion Engineering and Design, 2016
Short fiber reinforced SiC/SiC composites with high fiber volume fraction were fabricated by NITE... more Short fiber reinforced SiC/SiC composites with high fiber volume fraction were fabricated by NITE process. The effects of fiber length and sintering condition on microstructure and mechanical properties were investigated. Although, high sintering temperature promotes the densification of SiC matrix but leads to the degradation of F/M interface. The flexural strength of SF-SiC/SiC with long fiber length shows higher flexural strength compared to those of SF-SiC/SiC with short fiber length. SF-SiC/SiC composites with complicated shape have been successfully fabricated by pseudo-HIP.
Materials Science Forum, 2005
Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxyg... more Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxygen partial pressures were applied to investigate the tensile properties and creep behavior of SiC fibers such as Hi-NicalonTM and TyrannoTM-SA. These fibers were annealed and crept at elevated temperatures ranging from1273-1773 K in such environments. After annealing at 1773 K, the room temperature tensile strengths of SiC-based fibers decreased with decreasing the oxygen partial pressure and the near stoichiometric fiber TyrannoTM-SA shows excellent strength retention. At temperatures above the 1573 K, the creep resistance of SiC fibers evaluated by bending stress relaxation (BSR) method under high oxygen partial pressure was lower than that of in low oxygen partial pressure. The microstructural features on these fibers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).
Advanced Composite Materials, Sep 11, 2018
SiC fiber-reinforced SiC matrix (SiC/SiC) composites are expected as a high-temperature structura... more SiC fiber-reinforced SiC matrix (SiC/SiC) composites are expected as a high-temperature structural material for the application of aerospace and nuclear energy system due to their high-temperature stability, reduced-activation property, and excellent irradiation resistance. It was investigated the size effects of test specimen on the fracture behaviour and apparent strength of SiC/SiC tubes in order to minimize the size of test specimen, as well as to develop circumferential tensile test method for SiC/SiC fuel cladding of nuclear reactor. The tube specimens with a narrow width (less than 5 mm) represented the stable value of apparent strength. In case of wide width (>5 mm), the apparent strength of test specimen decreased with the increase in specimen width. It was observed that the fracture of the test specimen with wide width was initiated from the sides of test specimen due to the local contact between loading pin and the test specimen. It is required to use the material with high modulus as a loading pin material in order to avoid the stress concentration caused by local contact.
Fusion Engineering and Design
Journal of Nuclear Materials
Nuclear Materials and Energy, 2022
Fusion Engineering and Design, 2016
Abstract SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate materi... more Abstract SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate material for the first-wall, components in the blanket and divertor of fusion reactors in future. In such components, SiC/SiC composites need to be formed to be various shapes. SiC/SiC tubes has been expected to be employed for blanket and divertor after DEMO reactor, but there is not established mechanical investigation technique. Recent progress of SiC/SiC processing techniques is likely to realize strong, having gas tightness SiC/SiC tubes which will contribute for the development of fusion reactors. This research studies the relationship between deformation and strain of SiC/SiC tube using a circumferential tensile test method to establish a mechanical property investigation method of SiC/SiC tubes.
Fusion Engineering and Design, 2016
Short fiber reinforced SiC/SiC composites with high fiber volume fraction were fabricated by NITE... more Short fiber reinforced SiC/SiC composites with high fiber volume fraction were fabricated by NITE process. The effects of fiber length and sintering condition on microstructure and mechanical properties were investigated. Although, high sintering temperature promotes the densification of SiC matrix but leads to the degradation of F/M interface. The flexural strength of SF-SiC/SiC with long fiber length shows higher flexural strength compared to those of SF-SiC/SiC with short fiber length. SF-SiC/SiC composites with complicated shape have been successfully fabricated by pseudo-HIP.
Materials Science Forum, 2005
Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxyg... more Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxygen partial pressures were applied to investigate the tensile properties and creep behavior of SiC fibers such as Hi-NicalonTM and TyrannoTM-SA. These fibers were annealed and crept at elevated temperatures ranging from1273-1773 K in such environments. After annealing at 1773 K, the room temperature tensile strengths of SiC-based fibers decreased with decreasing the oxygen partial pressure and the near stoichiometric fiber TyrannoTM-SA shows excellent strength retention. At temperatures above the 1573 K, the creep resistance of SiC fibers evaluated by bending stress relaxation (BSR) method under high oxygen partial pressure was lower than that of in low oxygen partial pressure. The microstructural features on these fibers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).
Advanced Composite Materials, Sep 11, 2018
SiC fiber-reinforced SiC matrix (SiC/SiC) composites are expected as a high-temperature structura... more SiC fiber-reinforced SiC matrix (SiC/SiC) composites are expected as a high-temperature structural material for the application of aerospace and nuclear energy system due to their high-temperature stability, reduced-activation property, and excellent irradiation resistance. It was investigated the size effects of test specimen on the fracture behaviour and apparent strength of SiC/SiC tubes in order to minimize the size of test specimen, as well as to develop circumferential tensile test method for SiC/SiC fuel cladding of nuclear reactor. The tube specimens with a narrow width (less than 5 mm) represented the stable value of apparent strength. In case of wide width (>5 mm), the apparent strength of test specimen decreased with the increase in specimen width. It was observed that the fracture of the test specimen with wide width was initiated from the sides of test specimen due to the local contact between loading pin and the test specimen. It is required to use the material with high modulus as a loading pin material in order to avoid the stress concentration caused by local contact.
Fusion Engineering and Design