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Nb 첨가 철계 합금의 Prior austenite 결정립크기 측정 방법
고광규,배효주,정신우,성효경,김정기,설재복,Ko, Kwang Kyu,Bae, Hyo Ju,Jung, Sin Woo,Sung, Hyo Kyung,Kim, Jung Gi,Seol, Jae Bok 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.4
High-strength low-alloy (HSLA) steels show excellent toughness when trace amounts of transition elements are added. In steels, prior austenite grain size (PAGS), which is often determined by the number of added elements, is a critical factor in determining the mechanical properties of the material. In this study, we used two etching methods to measure and compare the PAGS of specimens with bainitic HSLA steels having different Nb contents These two methods were nital etching and picric acid etching. Both methods confirmed that the sample with high Nb content exhibited smaller PAGS than its low Nb counterpart because of Nb's ability to hinder austenite recrystallization at high temperatures. Although both etching approaches are beneficial to PAGS estimation, the picric acid etching method has the advantage of enabling observation of the interface containing Nb precipitate. By contrast, the nital etching method has the advantage of a very short etching time (5 s) in determining the PAGS, with the picric acid etching method being considerably longer (5 h).
Seongmin Hong,JeongGon Kim,CheolGi Kim 한국자기학회 2009 Journal of Magnetics Vol.14 No.2
The magnetic and structural properties of FINEMET (the Hitachi product name of the Fe-Si-B-Nb-Cu alloy) nanopowder with a composition of Fe73.5Si13.5B?Nb₃Cu₁ atomic percent were investigated after annealing, chemical etching, and mechanical milling. The primary and secondary crystallization temperatures were 523 and 550 ℃, respectively. The grain size of the particles was adjusted by annealing time. Optimally annealed particles exhibited a homogenous microstructure composed of nanometer-sized crystalline grains. The grain boundary of the annealed particles was etched preferentially by chemical etching. Chemically etched particles were broken at the grain boundary by high-energy ball milling. As a result, a nanometer-sized FINEMET powder with a uniform size of crystalline grains was fabricated.
Bok, Won-Mi,Kim, Seo-Young,Lee, Sook-Jeong,Shin, Gwi-Su,Park, Ju-Mi,Lee, Min-Ho Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.10
Titanium and titanium alloys are amenable to processing as dental implant materials because of their low density, good mechanical properties, better biocompatibility, and excellent corrosion resistance. However, titanium-based implants cannot bond directly to bone. To induce osseointegration, numerous surface-treatment techniques have been investigated over the years to improve implant performance. In this study, we examine sandblasting and acid etching (SLA) methods to determine the various properties of SLA-treated Ti-10Nb-10Ta alloy. The SLA treatment included two steps: first, mechanically polished Ti-10Nb-10Ta alloy was subjected to grit blasting using <TEX>$110-{\mu}m$</TEX> alumina particles, and second, the blasted alloy underwent acid etching for 9 minutes with a mixture of <TEX>$H_2SO_4$</TEX> and HCl at <TEX>$100^{\circ}C$</TEX>. After etching with Keller's etchant, the Ti-10Nb-10Ta alloy showed a lamellar structure on optical microscopy, and surface roughness was increased after SLA treatment (p<0.05). The apatite layer that formed on the SLA-treated Ti-10Nb-10Ta alloy after immersion in simulated body fluid was approximately <TEX>$2{\mu}m$</TEX> thick, thus improving adhesion to bone. Wettability of the SLA-treated Ti-10Nb-10Ta alloy was better than that of the non-treated one. In vitro studies showed no cytotoxicity from either the untreated or the SLA-treated Ti-10Nb-10Ta alloys.
연구 논문 : 전기화학적 마이크로머시닝 기술을 이용한 균일한 니오븀 표면 에칭 연구
김경민 ( Kyung Min Kim ),유현석 ( Hyeon Seok Yoo ),박지영 ( Ji Young Park ),신소운 ( So Woon Shin ),최진섭 ( Jin Sub Choi ) 한국공업화학회 2014 공업화학 Vol.25 No.1
본 연구에서는 micro-contact printing을 통하여 니오븀 호일 표면 위에 균일한 에칭 pits를 형성하였다. 균일한 보호층을 형성하고자 전해연마의 효과를 확인하였으며, 기존의 O2 플라즈마 공정 없이 손쉽게 균일한 에칭 pits를 형성시킬 수 있는 조건을 확인하였다. 메탄올 혼합 전해질을 사용하여 10 min 동안 에칭을 진행한 결과 니오븀 호일 표면 위에 지름과 간격이 각각 10 μm와 5 μm로 잘 정렬된 에칭 pits를 관찰하였다. We describe the preparation of highly-ordered etching pits on the Nb foil through a micromachining. The effects of electro-chemical polishing on the formation of uniformly-patterned protective epoxy layer was investigated. Unlike the previous proc-ess using O2 plasma, well-ordered etched pits were prepared without any dry processes. As a result, the Nb foil with the well-ordered pits of 10 μm × 5 μm could be obtained by electrochemical etching in methanolic electrolytes for 10 min.