HWAHAK KONGHAK, Vol.41, No.2, 232-237, April, 2003
Sol-Gel법에 의한 Yttria-Stabilized Ziroconia(YSZ) 나노분말의 제조
Preparation of Yttria-Stabilized Zirconia(YSZ) Nanopowders by Sol-Gel Method
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초록
Sol-Gel법에 의해 출발물질로 zirconium-n-butoxide(ZNB)와 yttrium nitrate를 사용하여 yttria-stabilized zirconia(YSZ) 나노분말을 제조하였다. 또한 ZNB의 가수분해 동안 첨가된 yttria양의 변화가 제조된 YSZ 나노분말의 결정상 조성과 기공특성에 미치는 영향을 조사하였다. 100 ℃에서 건조된 분말들은 모두 비정질상이었으며, 400 ℃에서 입방정상의 결정구조로 전환되었다. Yttria가 첨가되지 않고 제조된 분말들은 800 ℃에서 단사정상과 정방정상이 공존하는 혼합 상으로 상전이가 일어났으며, 1,200 ℃ 이상에서는 순수한 단사정상의 결정 구조를 보였다. 반면에 적당량의 yttria가 첨가된 분말에서는 (2.5 YSZ, 4 YSZ) 1,000 ℃ 이상의 온도에서 정방정상만을 나타내었다. 또한 yttria가 첨가되어 제조된 후 800 ℃에서 열처리된 분말들은 mesopore의 기공분포를 보인 반면, yttria가 첨가되지 않은 순수한 zirconia의 경우에는 macropore의 기공분포를 보였다.
Nanosized YSZ powders were synthesized by sol-gel method using zirconium n-butoxide(ZNB) and yttrium nitrate as precursors. In addition, the effect of yttria content added during hydrolysis reaction of ZNB was investigated on the crystalline phase composition and pore structure of the product powders. All powders dried at 100 ℃ were amorphous and crystallized to cubic phase at 400 ℃. Crystalline phase of the powders made without yttria changed from the cubic to a phase
in which monoclinic and tetragonal crystals coexist at 800 ℃ and then transformed to a pure monoclinic phase above 1,200 ℃. In contrast, the powders made with adequate content of yttria (2.5 YSZ, 4 YSZ) showed only the tetragonal phase above 1000 ℃. The pore size distributions of the powders prepared with yttria and calcined at 800 ℃ showed mesopores, while those prepared without yttria and calcined at the same temperature exhibited macropores.
Keywords:Yttria-Stabilized Zirconia;Nanopowders;Sol-Gel Method;Zirconium-n-Butoxide;Phase Composition;Pore Structure
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