Name: Rodolpho Santos Lepich
Type: MSc dissertation
Publication date: 21/03/2017

Namesort descending Role
Carlos Augusto Cardoso Passos Advisor *
Cherlio Scandian Co-advisor *

Examining board:

Namesort descending Role
Carlos Augusto Cardoso Passos Advisor *
Cherlio Scandian Co advisor *
José Luis Passamai Junior External Examiner *
Marcos Tadeu DAzeredo Orlando Internal Examiner *

Summary: Pre-prepared SmBa2Cu3O7-d polycrystalline superconducting samples were deposited in lean duplex stainless steel and heat-treated with different oxygen flows: 0.2 cm³/s, 0.5 cm³/s and 0.7 cm³/s. In addition, an attempt to heat treatment under an inert argon gas atmosphere was performed. The samples were labeled as A and B, due to the different synthesis processes to which they were submitted. So, to be deposited in the steel it was necessary to create a pit approximately 5cm long by 2mm wide. Through two different processes, corrosion and milling cutter, gave rise to the central channel. After visual analysis, it was noticed that the milling cutter process obtained higher quality and productivity. The superconducting ceramic powder was deposited on the steel and then the material was brought into the furnace for heat treatment. Afterwards, the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), as well as the calculation of the mean size of the junction. From the XRD results, it was found that samples A did not form the desired stoichiometry, WHEREas samples B did. It was observed that the lower the oxygen flow, the greater the mean size of the junctions. Consequently, the magnetic shielding is higher. The smaller sizes offer less resistance to the passage of electric current, therefore, the lower the probability of forming hot spots and degrading the grain boundaries. Finally, an ideal route for a creation of this composite was found: B synthesis process and thermal treatment under oxygen flow of 0.5 cm³/s. In this case, the desired stoichiometry with a relevant percentage of the orthorhombic and tetragonal phase was formed, however, none of the materials tested showed superconducting transition above 77K.

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