ISSN 2594-5327
57º Congresso anual — Vol. 57 , num. 1 (2002)
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The Bi₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) oxide is the most suitable superconductor for producing electric cables operating above the liquid nitrogen temperature (77 K). The Bi-2223 phase is normally obtained through long time sintering of a precursor powder. Alternatively, the Bi-2223 formation from the melt could lead to higher densities and texture, increasing significantly the highly anisotropic current transport. To our knowledge, however, Bi-2223 formation from the melt has not been reported so far, due to the narrow equilibrium range and sluggish formation kinetics of that phase. In the present work, the feasibility of this process and the involved phase relations have been investigated. Therefore, precursor powders with different nominal compositions were packed into silver crucibles for melting and subsequent slow-cooling. Silver was employed because it is the sheathing material for Bi-2223 wires, due to a high physical and chemical compatibility with the superconducting oxide. The samples were quenched from different temperatures, in order to study the evolution of phase and microstructure through X-ray diffraction and scanning electron microscopy. The precursors decomposed peritectically during melting, forming liquid and secondary solid phases. The Bi-2223 phase has been observed after cooling and the results suggest that long Bi-2223 grains may form by this process.
The Bi₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) oxide is the most suitable superconductor for producing electric cables operating above the liquid nitrogen temperature (77 K). The Bi-2223 phase is normally obtained through long time sintering of a precursor powder. Alternatively, the Bi-2223 formation from the melt could lead to higher densities and texture, increasing significantly the highly anisotropic current transport. To our knowledge, however, Bi-2223 formation from the melt has not been reported so far, due to the narrow equilibrium range and sluggish formation kinetics of that phase. In the present work, the feasibility of this process and the involved phase relations have been investigated. Therefore, precursor powders with different nominal compositions were packed into silver crucibles for melting and subsequent slow-cooling. Silver was employed because it is the sheathing material for Bi-2223 wires, due to a high physical and chemical compatibility with the superconducting oxide. The samples were quenched from different temperatures, in order to study the evolution of phase and microstructure through X-ray diffraction and scanning electron microscopy. The precursors decomposed peritectically during melting, forming liquid and secondary solid phases. The Bi-2223 phase has been observed after cooling and the results suggest that long Bi-2223 grains may form by this process.
Palavras-chave
Bi-2223 high-Tc superconductor, melting and slow-cooling
Bi-2223 high-Tc superconductor, melting and slow-cooling
Como citar
Polasek, Alexander; Majewski, Peter; Assunção, Fernando Cosme Rizzo; Amado, Luís Antônio Saléh; Serra, Eduardo Torres.
PROCESSING THE BI-2223 HIGH-TC SUPERCONDUCTOR BY MELTING AND SLOW-COOLING,
p. 355-365.
In: 57º Congresso anual,
São Paulo, Brasil,
2002.
ISSN: 2594-5327, DOI 10.5151/2594-5327-C01365
