화학공학소재연구정보센터
Journal of the Korean Industrial and Engineering Chemistry, Vol.9, No.7, 1011-1017, December, 1998
발화합성법에 의한 YBa2Cu3O6+x 초전도 선재의 제조
Preparation of YBa2Cu3 O6+x Superconducting Wires Prepared by Pyrophoric Synthetic Technique
초록
YBa2Cu3O6+x(Y123)-Ag 초전도 선재를 0/20 wt%의 은(Ag)을 첨가한 발화합성분말과 고상반응분말을 사용하여 플라스틱 압출법으로 제조하였다. 플라스틱 압출법은 분말제조, 플라스틱 paste 제조, 다이 압축, binder 소각 및 소결공정을 포함한다. 양질의 초전도체를 제조하려면 원료물질이 균질하고 미세한 분말이어야 한다. 0/20 wt%를 첨가한 Y2O3-BaCO3-CuO precursor 분말을 발화합성(PS)법과 고상반응(MM)법으로 제조하였다. 원료분말이 Y123 초전도상으로 전이되는 생성속도를 공기중에서 여러온도와 시간별로 반응시켜 알아보았다. 발화합성법으로 제조한 분말이 고상반응법으로 제조한 분말보다 Y123상으로 빠르게 전이되었다. 이것은 PS법으로 제조한 분말이 미세한 크기와 균질한 화학적 조성으로 인해 Y123상으로 빠른 전이를 한 것이기 때문이다. 플라스틱 압출법으로 제조한 Y123-Ag 초전도 선재의 임계전류밀도(Jc)는 원료분말의 특징에 따라 150∼230 A/㎠값을 나타내었다. 은을 20 wt.% 첨가한 발화합성분말로 제조한 선재의 Jc는 230 A/㎠이었다.
YBa2Cu3O6+x(Y123)-Ag high-T c superconducting wires were fabricated by plastic extrusion technique using pyrophoric synthetic and mechanical mixing powder with and without Ag addition(20 wt.%). This method involves powder preparation, plastic paste making, die extrusion, binder burn-out and the sintering process. In order to fabricate a good-quality superconducting body, it is required to use homogeneous and fine-size power as a starting materials. Y2O3-BaCO3-CuO precursor powders with/without Ag addition were prepared both by pyrophoric synthetic(PS) and mechanical mixing(MM) method of raw powders. The formation kinetics of the powder mixtures into Y123 phase was investigated at various temperatures and times in air atmosphere. The powder prepared by PS method was more easily converted into a Y123 phase than the MM powder. The fine size and good chemical homogeneity of the powder prepared by PS method is attributable to the fast formation into a Y123 phase. The critical current density(Jc) of the Y123-Ag superconducting wires made by plastic extrusion method were in the range of 150 A/㎠∼230 A/㎠. depending on the charateristics of starting material powders. Jc of the wire prepared by pyrophoric synthetic powder with 20 wt.% Ag addition was 230 A/㎠.
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