https://pubs.kist.re.kr/handle/123456789/75386 2026-04-15T18:22:24Z 2026-04-15T18:22:24Z Ok, Myoung-Ryul Kang, Eun Young Kim, Ji Hye Ji, Young Su Lee, Chang Woo Oh, Young-Joo Hong, Kyung Tae https://pubs.kist.re.kr/handle/201004/116452 2024-01-26T07:41:26Z 2007-01-01T00:00:00Z

Title: Analysis on the microstructure of ceramic coating layer fabricated by plasma electrolytic oxidation Authors: Ok, Myoung-Ryul; Kang, Eun Young; Kim, Ji Hye; Ji, Young Su; Lee, Chang Woo; Oh, Young-Joo; Hong, Kyung Tae Abstract: Plasma electrolytic oxidation (PEO) has drawn attention and been studied intensively all through the world. The thick ceramic coatings fabricated by the technique exhibit excellent properties, including hardness and wear resistance, thermal and electrical insulation, and corrosion resistance, due to the characteristic phase composition and microstructure of the coating layers. However, most of the studies have dealt with manufacturing process itself and the apparent properties of coating layers and researches on the microstructural basis including transmission electron microscopy analysis are limited so far. In this investigation, a basic approach to PEO process was tried, adapting time-potential behavior analysis under constant current mode (galvanostatic) oxidation, and microstructural analysis on the coating structure, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The time-potential behavior analysis under constant current DC was carried out, and the resultant evolution of the microstructure was characterized..

2007-01-01T00:00:00Z Bae, Deuck Seung Jung, Woo Sang Hong, Suk Woo Song, Sang Min Chung, Soon Hyo Hong, Kyung Tae Lee, Kyung Sub https://pubs.kist.re.kr/handle/201004/116451 2024-01-26T07:41:24Z 2007-01-01T00:00:00Z

Title: Coarsening of MX nitrides in Cr-Mo-N-X(X=V,Nb,Ti) ferritic steels Authors: Bae, Deuck Seung; Jung, Woo Sang; Hong, Suk Woo; Song, Sang Min; Chung, Soon Hyo; Hong, Kyung Tae; Lee, Kyung Sub Abstract: Ferritic steels have been candidate structural materials for first wall and blanket structures of fusion power plant since the late 1970's, when the fast-reactor irradiation showed them to be more swelling resistant than austenitic stainless steels. In this investigation, the coarsening of NIX nitrides during aging was studied for Cr-Mo-N-X(X=V, Nb, Ti) ferritic steels. During the aging, (V, Nb, Ti)nitrides were precipitated out. From TEM observation, particle size distribution was confirmed and size distribution follows a typical log-normal distribution. The coarsening rate of NIX nitrides was correlated with the Oswald ripening equation.

2007-01-01T00:00:00Z Kim, Bong Hoon Koo, Chong Min Jeong, Seong Jun Shin, Dong Ok Kim, Sang Ouk https://pubs.kist.re.kr/handle/201004/116450 2024-01-26T07:41:22Z 2007-01-01T00:00:00Z

Title: Self-assembled nanostructures of block copolymers on random copolymer brush Authors: Kim, Bong Hoon; Koo, Chong Min; Jeong, Seong Jun; Shin, Dong Ok; Kim, Sang Ouk Abstract: We synthesized the polymer brushes by conventional free radical polymerization and investigated the morphology evolution of block copolymer nanostructure on the brush treated surfaces. Our simple approach utilized a functionalized free radical initiator to add hydroxyl group to a chain end and an excess amount of a chain transfer agent to control the molecular weights of the brushes. The synthesized polymer brushes had narrow molecular weight distribution as well as hydroxyl end group and were successfully grafted onto silicon oxide layer by simple spin-coating and annealing process. The orientation of poly(styrene-block-methyl methacrylate)s (PS-b-PMMAs) coated on the brush grafted surface was finely controlled by the surface modification by polymer brushes.

2007-01-01T00:00:00Z Han, Jae-Ho Park, Sang-Whan Kim, Young-Do https://pubs.kist.re.kr/handle/201004/116449 2024-01-26T07:41:19Z 2007-01-01T00:00:00Z

Title: Synthesis and mechanical properties of nano laminating Cr2AlC using CrCx/Al powder mixtures Authors: Han, Jae-Ho; Park, Sang-Whan; Kim, Young-Do Abstract: Cr2AlC, one of the ternary carbide families, was synthesized by a reactive hot pressing of CrCx (x=0.5) and At powder mixture used as starting materials at the temperature range of 1200 degrees C-1400 degrees C under 25 MPa in Ar atmosphere. Fully dense Cr2AlC with high purity was synthesized by hot pressing CrCx and Al powder mixture at the temperature as low as 1200 degrees C. After synthesizing the bulk Cr2AlC, it was found that it has a typical layered structure as found in other ternary carbides such as Ti3AlC2 and Ti3SiC2. The average grain size of synthesized bulk Cr2AlC was varied in the range of 10-100 mu m depending on hot pressing temperatures. The Vickers hardness of bulk Cr2AlC was less than 4 GPa under the loading of 10N and this decreased with increasing indentation load. The maximum flexural strength of synthesized bulk Cr2AlC exceeded 600 MPa. Also, it was found that synthesized Cr2AlC was readily machinable by a conventional WC tool bit due to its low hardness as well as damage tolerance properties upon fracture.

2007-01-01T00:00:00Z