Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Fabrication of Porous W by Freeze-Drying Process of Camphene Slurries with Spherical PMMA and WO3 Powders

구형 PMMA와 WO3 분말이 혼합된 Camphene 슬러리의 동결건조에 의한 W 다공체 제조

  • Lee, Han-Eol (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Jeon, Ki Cheol (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Kim, Young Do (Division of Materials Science and Engineering, Hanyang University) ;
  • Suk, Myung-Jin (Department of Materials and Metallurgical Engineering, Kangwon National University) ;
  • Oh, Sung-Tag (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
  • 이한얼 (서울과학기술대학교 신소재공학과) ;
  • 전기철 (서울과학기술대학교 신소재공학과) ;
  • 김영도 (한양대학교 신소재공학부) ;
  • 석명진 (강원대학교 재료금속공학과) ;
  • 오승탁 (서울과학기술대학교 신소재공학과)
  • Received : 2015.08.28
  • Accepted : 2015.09.22
  • Published : 2015.11.27

Abstract

Porous W with spherical and directionally aligned pores was fabricated by the combination of sacrificial fugitives and a freeze-drying process. Camphene slurries with powder mixtures of $WO_3$ and spherical PMMA of 20 vol% were frozen at $-25^{\circ}C$ and dried for the sublimation of the camphene. The green bodies were heat-treated at $400^{\circ}C$ for 2 h to decompose the PMMA; then, sintering was carried out at $1200^{\circ}C$ in a hydrogen atmosphere for 2 h. TGA and XRD analysis showed that the PMMA decomposed at about $400^{\circ}C$, and $WO_3$ was reduced to metallic W at $800^{\circ}C$ without any reaction phases. The sintered bodies with $WO_3$-PMMA contents of 15 and 20 vol% showed large pores with aligned direction and small pores in the internal walls of the large pores. The pore formation was discussed in terms of the solidication behavior of liquid camphene with solid particles. Spherical pores, formed by decomposition of PMMA, were observed in the sintered specimens. Also, microstructural observation revealed that struts between the small pores consisted of very fine particles with size of about 300 nm.

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Acknowledgement

Supported by : National Research Foundation of Korea(NRF)

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