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동결건조 공정에서 Tert-butyl alcohol 기공형성제가 텅스텐 다공체의 기공구조에 미치는 영향
이의선,허연지,고윤택,박진경,좌용호,오승탁,Lee, Eui Seon,Heo, Youn Ji,Ko, Yun Taek,Park, Jin Gyeong,Cho, Yong-Ho,Oh, Sung-Tag 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.3
The effect of tert-butyl alcohol (TBA) as a freezing solvent on the pore structure of a porous tungsten body prepared by freeze-drying is analyzed. TBA slurries with a WO3 content of 10 vol% are prepared by mixing with a small amount of dispersant and binder at 30℃. The slurries are frozen at -25℃, and pores are formed in the frozen specimens by the sublimation of TBA during drying in air. After hydrogen reduction at 800℃ and sintering at 1000℃, the green body of WO<sub>3</sub> is completely converted to porous W with various pore structures. Directional pores from the center of the specimen to the outside are observed in the sintered bodies because of the columnar growth of TBA. A decrease in pore directionality and porosity is observed in the specimens prepared by long-duration drying and sintering. The change in pore structure is explained by the growth of the freezing solvent and densification.
전기방사를 이용하여 합성한 BiVO<sub>4</sub> 나노섬유의 미세구조와 광촉매 특성에 하소 온도가 미치는 영향
지명준,김정현,류철희,고윤택,이영인,Ji, Myeongjun,Kim, Jeong Hyun,Ryu, Cheol-Hui,Ko, Yun Taek,Lee, Young-In 한국분말야금학회 2020 한국분말재료학회지 (KPMI) Vol.27 No.3
Bismuth vanadate (BiVO<sub>4</sub>) is considered a potentially attractive candidate for the visible-light-driven photodegradation of organic pollutants. In an effort to enhance their photocatalytic activities, BiVO<sub>4</sub> nanofibers with controlled microstructures, grain sizes, and crystallinities are successfully prepared by electrospinning followed by a precisely controlled heat treatment. The structural features, morphologies, and photo-absorption performances of the asprepared samples are systematically investigated and can be readily controlled by varying the calcination temperature. From the physicochemical analysis results of the synthesized nanofiber, it is found that the nanofiber calcines at a lower temperature, shows a smaller crystallite size, and lower crystallinity. The photocatalytic degradation of rhodamine-B (RhB) reveals that the photocatalytic activity of the BiVO<sub>4</sub> nanofibers can be improved by a thermal treatment at a relatively low temperature because of the optimization of the conflicting characteristics, crystallinity, crystallite size, and microstructure. The photocatalytic activity of the nanofiber calcined at 350℃ for the degradation of RhB under visible-light irradiation exhibits a greater photocatalytic activity than the nanofibers synthesized at 400℃ and 450℃.
차정은(Cha, Jung-Eun),전희권(Jun, Hee-Kwon),박정주(Park, Jung-Joo),고윤택(Ko, Youn-Taek),황정태(Hwang, Jung-Tae),장원철(Chang, Won-Chol),김진영(Kim, Jin-Young),김태원(Kim, Tae-Won),김인기(Kim, In-Ki),정영식(Jeong, Young-Sik),갈한주(K 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
To extract hydrogen for stack, fuels such as LPG and LNG were reformed in the fuel processor, which is comprised of desulfurizer, reformer, shift converter, CO remover and steam generator. All elements of fuel processor are integrated in a single package. Highly active catalysts (desulfurizing adsorbent, reforming catalyst, CO shift catalyst, CO removal catalyst) and the various burners were developed and evaluated in this study. The performance of the developed catalysts and the commercial ones was similar. 1 kW, 5 kW class fuel processor systems using the developed catalyst and burner showed efficiency of 75 %(LHV, for LNG). The start-up time of the 1 kW class fuel processor was less than 50 minutes and its volume including insulation was about 30 l. The start-up time of 3 kW and 5 kW class fuel processors with the volume of 90 l and 150 l, respectively, was about 60 minutes. In the case of LPG fuel, efficiency, volume and start-up time of 1kW class fuel processor showed 73 %(LHV), < 60 l and < 60 min, respectively. Advanced fuel processor showed more highly efficiency and shorter start-up time due to the improvement of heat exchanger and operating method. 1 kW and 3 kW class fuel processors have been evaluated for reliability and durability including with on/off test of developed catalysts and burner.