Fabrication of porous geopolymer using fused slag with silicon sludge

김유택,김성열,장창섭 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.11

Geopolymers release 80% less carbon dioxide than Portland cement and simultaneously provide sufficient mechanical strengthfor structural applications. Therefore, they were worth as cement substitutes and have attracted from eco-friendly constructionindustries. Spent silicon sludge is increasing as the demand of silicon wafer for the solar energy generation and semiconductoris steadily increasing. Silicon sludge is produced from the cutting and grinding process of silicon ingot for making silicon wafer. In this study, silicon sludge is used as bloating agent for making porous geopolymers with spent industrial wastes such as fusedslags from IGCC (integrated gasification combined cycle) process or municipal waste treatment system. The compressivestrength and density of porous geopolymers decreased with silicon sludge addition. Because high addition of silicon sludge tofused slags under the high alkaline atmosphere releases much of H2 gas, highly porous geopolymers could be obtained in ashort curing period. However, high silicon content also showed adversely effects on polymerization process. Geopolymers withspecific gravity less than 0.4 was fabricated by using silicon sludge and fused slag; having compressive strength up to 1.3 MPa. In conclusion, very light and porous geopolymers having relatively higher compressive strength could be fabricated with fusedslag and spent silicon sludge as a bloating agent.

Microstructural analysis of geopolymers using fused slags with transmission electron microscopy

김유택,이경우 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.4

The amount of fused slag generated is continuously increasing and is expected to reach 50,000 tons per year as coal gasificationfacilities and waste treatment systems producing fused slag have been actively adopted recently in Korea. One of theprospective solutions is to make geopolymers with the slags because geopolymers are a cement substitute that can reduce thegeneration of carbon dioxide and have thus attracted increasing interest from recycling and eco-friendly constructionindustries because they provide sufficient mechanical strength for application in construction materials. There has not yet beena comprehensive microscopic investigation of geopolymers or diffraction pattern analysis of the crystallites produced bygeopolymerization. Geopolymers made of fused slags with an alkali activator exhibited very high compressive strengthcompared with those of ordinary geopolymers, and their microscopic structures were analyzed by transmission rlectronmicroscopy (TEM) to confirm the formation of crystallites during the geopolymerization and to explain the relationshipbetween the microstructure and mechanical property of the geopolymers. At least two types of phases, C-S-H and Ca(OH)2,have been identified by selected area diffraction (SAD) pattern analyses on the crystallites in the geopolymer matrix.

석탄회 및 용융폐기물 슬래그에 소량의 알칼리 활성화제를 첨가한 무시멘트 모르타르의 특성

김유택,이경우,Kim, Yootaek,Lee, Kyongwoo 한국결정성장학회 2015 한국결정성장학회지 Vol.25 No.6

Recently the world wide efforts reduce occurrence of $CO_2$; global warming main reason. The aim of this study is to improve recycling rate of the fly ash (FA) and fused waste slag (FWS) from the power plant and to carbonate under supercritical condition ($40^{\circ}C$, $80kgf/cm^2$ pressure, 60 min) for $CO_2$ fixation. Specimens of mortar with various mixing ratios of FA, FWS (from 100:0 to 20:80 in 5 steps of 20 % reduction each time), distilled water and 3 M NaOH alkali activators were prepared. As a result, the proportion of weight change ratio increases with CaO content, to 12 % after carbonation under the supercritical condition. There is difference of compressive strength between the carbonated and the alkali activator mortar specimens. The stabilization of $CO_2$ fixation through carbonation which could confirm the applicability of the eco-friendly materials without loss of compressive strength.

준불연 초경량 지오폴리머의 물성

김유택,Kim, Yootaek 한국결정성장학회 2019 한국결정성장학회지 Vol.29 No.3

EPS 단열재는 우수한 단열성능과 경제성, 초경량 등의 장점으로 각광받고 있는 건축재이다. 하지만 EPS 단열재는 가연성 물질로서 화재 시 연소되기 쉽고, 유해가스를 방출시킴으로써 대규모 인명피해를 유발 시킬 수 있다. 따라서 본 논문에서는 산업부산물인 IGCC fused slag 및 Si sludge를 활용하여 초경량 지오폴리머를 제작하고, EPS 단열재의 대체 가능성에 대해 확인하고자 하였다. 그 결과, 조분쇄 상태의 탄소 함량이 적은 IGCC fused slag를 이용하였을 경우 0.04 MPa, $0.064g/cm^3$의 압축강도 및 밀도를 갖는 초경량 지오폴리머를 제작할 수 있었고, 이때의 열전도율은 0.072 W/mK을 나타내었다. 이는 KS M 3808에서 제시하는 EPS 열전도율 값의 1.5~2배 정도의 높은 물성이지만 시중에서 판매하는 EPS 단열재와 큰 차이가 없으며 보통 매립되는 산업 부산물을 재활용한다는 점과 세라믹 재료 특성상 화재시에도 고온에서 버틸 수 있다는 큰 장점이 있기 때문에 화재시 쉽게 발화되어 다량의 유독가스를 방출시키는 EPS 단열재의 단점을 해결할 수 있는 차세대 단열재로서의 가능성은 충분하다고 판단되었다.

스마트 센서로의 적용을 위한 탄소섬유 복합체의 특성평가 (I)

김유택 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.1

Polyacrylonitrile(PAN)-based 탄소섬유와 epoxy resin matrix 내에 장착된 PAN-based 탄소섬유의 전기저항을 탄소섬유와 파괴될 때까지 인장강도를 증가시키며 측정하였다. 탄소섬유가 끊어져 측정 계기가 open-circuit을 나타내기 전까지 탄소섬유의 전기저항 값은 strain이 증가할수록 증가하였으며, epoxy resin은 탄소섬유의 저항값 측정에 거의 영향을 미치지 않았다. 탄소섬유의 저항값 변화는 strain에 대해 정확도 1% 이내로 예측(calibrate)할 수 있었으며 재현성 또한 우수하였다. 따라서 탄소섬유는 재료의 기계적 강도를 증가시키기 위해 사용될 수 있을 뿐만 아니라 구조재료의 파괴를 예측할 수 있는 스마트 센서로서도 사용할 수 있다는 가능성을 확인하였다.

사파이어 {1120} 표면에 증착된 GaN 박막의 미세구조

김유택,박진호,신건철 한국결정성장학회 1998 한국결정성장학회지 Vol.8 No.3

GaN epilayers having good adhesion and quality were obtained directly on the sapphire {1120} substrates by the OMVPE method without introducing a buffer layer at the lower temperature. The preferred orientations of epilayers turned out to be <0002> and at least 4 kinds of epilayers were competitively grown. Slight distortions of lattices caused by lattice mismatches between sapphire and GaN were observed at the lattices within 2~3 nm region from the interface. Accordingly, TEM investigation revealed that GaN epilayers could be grown on sapphire {1120} planes without a buffer layer.

Adsorption behavior of heavy metal ions in the solutions of clay minerals under various conditions

김유택,J.H. Kim,K.G. Lee,강승구 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.1

The adsorption rates and characteristics of heavy metal ions (Cd, Cr, and Zn) were examined with solutions mixed with red clay, white clay, a mixture of red & white clay and zeolite under various pHs and initial concentrations. As expected, adsorption rates of heavy metal ions generally increased with increasing pH; however, Cr showed a particular behavior. A mixture of red & white clay among the clay minerals tried in this study showed the highest Cr adsorption rate at the low pH conditions (lower than pH 5) and red clay with additions of Cu, Fe and Pb ions at pH 5 showed above an 85% adsorption rate of Cr which was far from expectations. From the result, it is concluded that the adsorption characteristics of heavy metal ions depend not only on the physical properties of the absorbent itself such as the cation exchange capacity (CEC) but also on the concentration and existence of exchangeable cations, pH, ligands, etc.. The adsorption rates and characteristics of heavy metal ions (Cd, Cr, and Zn) were examined with solutions mixed with red clay, white clay, a mixture of red & white clay and zeolite under various pHs and initial concentrations. As expected, adsorption rates of heavy metal ions generally increased with increasing pH; however, Cr showed a particular behavior. A mixture of red & white clay among the clay minerals tried in this study showed the highest Cr adsorption rate at the low pH conditions (lower than pH 5) and red clay with additions of Cu, Fe and Pb ions at pH 5 showed above an 85% adsorption rate of Cr which was far from expectations. From the result, it is concluded that the adsorption characteristics of heavy metal ions depend not only on the physical properties of the absorbent itself such as the cation exchange capacity (CEC) but also on the concentration and existence of exchangeable cations, pH, ligands, etc..

Recycling of dust wastes as lightweight aggregates

김유택,J.H. Kim,K.G. Lee,강승구 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.2

Various kinds of industrial dust wastes were recycled by a wet ceramic process. Compounding various dusts gave allowed us compositional variation of dust wastes which originated from various places and conditions. One of the main problems for recycling wastes is caused by compositional variations. Success in recycling depends on how to control compositions and maintain the allowed purity level in the wastes. Grouping of dust wastes into three categories and compounding were introduced to raw material preparation processes for the successful recycling of various dusts. Pretreatment processes were also important to stabilize heavy metals in the raw materials. These processes consist of ion exchange, control of electrolyte concentration and pH etc. After these processes, industrial dust wastes were turned into safe, ecological construction materials such as bricks or lightweight aggregates by a final sintering process. Various kinds of industrial dust wastes were recycled by a wet ceramic process. Compounding various dusts gave allowed us compositional variation of dust wastes which originated from various places and conditions. One of the main problems for recycling wastes is caused by compositional variations. Success in recycling depends on how to control compositions and maintain the allowed purity level in the wastes. Grouping of dust wastes into three categories and compounding were introduced to raw material preparation processes for the successful recycling of various dusts. Pretreatment processes were also important to stabilize heavy metals in the raw materials. These processes consist of ion exchange, control of electrolyte concentration and pH etc. After these processes, industrial dust wastes were turned into safe, ecological construction materials such as bricks or lightweight aggregates by a final sintering process.

경제개발(經濟開發) 5개년계획(個年計劃)을 성공(咸功)시키는 길

김유택,Kim, Yu-Taek 한국과학기술정보연구원 과학기술정보센터 1963 Journal of Information Science Theory and Practice Vol.1 No.1

SiC/C 경사기능재료의 열충격 시험과 열응력 모사

김유택,이성철,최근혁 한국결정성장학회 1998 한국결정성장학회지 Vol.8 No.4

Monolithic SiC and SiC/C FGM layers were deposited on the graphite substrates by the CVD method and their thermal properties of the two specimens were investigated by thermal shock test for comparison. Temperature profiles and thermal stress distributions on thermal shock test were calculated by a commercially used computer program to see the thermal stress differences inside of two specimens. The specimens coated with FGM were expected to show a efficient relaxation of thermal stresses at the interface and they were not cracked under the actual $\Delta$T=1600 K experimental condition. This result proved that the experimental results were well accorded with the expectation from the theoretical calculations.