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A Study on the Deintercalation Reaction of Li-Graphite Intercalation Compounds
오원천,김범수,O, Won Cheon,Kim, Beom Su Korean Chemical Society 2000 Bulletin of the Korean Chemical Society Vol.21 No.1
Li-graphite intercalation compounds (GICs), synthesized at elevated temperature and pressure, were allowed to decompose spontaneously in the atmosphere. The decomposition processes were analyzed by of X-ray diffraction, DSC analysis, FT-IR measurements, UV/VIS spectrophotometry. The deintercalation reaction of the Li-GICs ceased after 6 weeks and only the residual compounds could be observed. A strong exothermic reaction was observed at 300 $^{\circ}C$ in thermal decomposition, and relatively stable decomposition curves were formed. A few endothermic curves have been observed at 1000 $^{\circ}C.$ After 6 weeks deintercalation reaction time of GICs, many exothermic and endothermic reactions were accompanied at the same time. In addition the reactions of the functional groups such as aromatic rings, nitrogen, $-CH_3$, $-CH_2$ etc. of GDIC obtained by the above reaction were confirmed by FT-IR spectrum. UV/VIS spectrophotometric measurement clearly shows the formation of a minimum energy value ($R_{min}$) for the compounds between Li-GICs as a starting material and Li-GDICs obtained until after 3 weeks of the deintercalation reaction, while they were no clear energy curves from 4 weeks of reaction time, because of the formation of the graphite structure, of high stages and of the Li compounds surrounding the graphite in the deintercalation reaction.
고로슬래그 60%를 혼입한 고강도 콘크리트의 강도발현 특성 및 내구성 평가
원천봉,양준모,김기돈,윤영수 한국방재학회 2018 한국방재학회논문집 Vol.18 No.7
This experimental study investigates material properties and durability of high-strength concrete (HSC) using ground-granulated blast-furnace slag (BS) and hooked steel fiber. The test results indicated that the compressive and flexural strengths of the BS-blended concretes are higher than those of ordinary Portland cement up to 28-day aging after steam curing. The porosity decreased with the usage of the BS, and thus, the matrix became dense. Therefore, the BS-blended HSC is highly impermeable to water, regardless of whether it undergoes cracking, and some negative effects on the resistance against freezing and thawing actions. In addition, it has low resistance to carbonation despite low amounts of calcium hydroxide. However, it was confirmed that used as structural materials can be resistant to carbonation in long-term durability. 본 연구에서는 고로슬래그 미분말과 후크형 강섬유를 사용한 고강도 콘크리트의 재료특성과 내구성을 평가하였다. 실험결과, 증기양생 후 고로슬래그 미분말을 혼입한 변수들(BS60, BS60-SF)은 재령 28일까지 OPC변수보다 상대적으로 우수한 압축 및 휨 인장강도 발현을 나타냈다. 고로슬래그 미분말의 혼입으로 공극율이 감소하고 매트릭스의 구조를 더 치밀하여 균열 유무에 관계없이 우수한 투수저항성을 나타내는 반면, 고로슬래그 미분말을 다량 혼입으로 인하여 상대적으로 동결융해 저항성능이 다소 감소한 거동을 나타냈다. 또한 수산화칼슘을 감소함으로써 OPC변수보다 상대적으로 중성화 저항성능이 감소하는 것을 나타냈으나, 실구조체에 적용할 경우 중성화에 대한 장기내구성능 확보가 가능함을 확인하였다.