텅스텐 다공체의 기공특성에 미치는 분말특성 및 동결조건의 영향
Effect of Powder Characteristic and Freeze Condition on the Pore Characteristics of Porous W
1
조회
0
다운로드
11
인용
0
참고문헌
키워드
초록
Dependence of the freeze-drying process condition on microstructure of porous W and pore formation mechanism were studied. Camphene slurries with WO3 contents of 10 vol% were prepared by milling at 50oC with a small amount of dispersant. Freezing of a slurry was done in Teflon cylinder attached to a copper bottom plate cooled at -25oC. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at 800oC for 30 min, and sintered in the furnace at 900oC for 1 h. After heat treatment in hydrogen atmosphere, WO3 powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about 70 μm which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores with dendritic structure due to the growth of camphene dendrite depending on the degree of nucleation and powder rearrangement in the slurry.
Abstract
Dependence of the freeze-drying process condition on microstructure of porous W and pore formation mechanism were studied. Camphene slurries with WO3 contents of 10 vol% were prepared by milling at 50oC with a small amount of dispersant. Freezing of a slurry was done in Teflon cylinder attached to a copper bottom plate cooled at -25oC. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at 800oC for 30 min, and sintered in the furnace at 900oC for 1 h. After heat treatment in hydrogen atmosphere, WO3 powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about 70 μm which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores with dendritic structure due to the growth of camphene dendrite depending on the degree of nucleation and powder rearrangement in the slurry.
참고문헌 (15)
- J. Banhart, , Prog. Mater. Sci., 46, pp.559~ (2001)
- H. Nakajima, , Prog. Mater. Sci., 52, pp.1091~ (2007)
- P. S. Liu, , J. Mater. Sci., 36, pp.5059~ (2001)
- T. Fukasawa, , J. Am. Ceram. Soc., 84, pp.230~ (2001)
- Y.-H. Koh, , J. Am. Ceram. Soc., 89, pp.3089~ (2006)
- T. Fukasawa, , J. Am. Ceram. Soc., 85, pp.2151~ (2002)
- K. K. Mallick, , J. Am. Ceram. Soc., 92, pp.85~ (2009)
- 김민수, "CuO-Camphene 슬러리의 동결건조에 의한 Cu 다공체 제조", 한국분말야금학회지, 18(4), pp.327~331 (2011), 한국분말야금학회
- S.-W. Yook, , Mater. Lett., 62, pp.4506~ (2008)
- 이영숙, "동결건조 공정을 이용한 텅스텐 다공체의 제조 및 특성", 한국재료학회지, 21(9), pp.520~524 (2011), 한국재료학회
- K. Araki, , J. Am. Ceram. Soc., 87, pp.1859~ (2004)
- 황해진, "동결건조공정을 이용한 다공성 세라믹스의 미세구조 제어", 한국세라믹학회지, 41(3), pp.229~ (2004), 한국세라믹학회
- B.-H. Yoon, , J. Am. Ceram. Soc., 90, pp.1753~ (2007)
- N.O. Shanti, , J. Am. Ceram. Soc., 89, pp.2444~ (2006)
- S. Deville, , Nature Mater, 8, pp.966~ (2009)