Optimization of Mechanical Properties in YBCO Ceramics via Silver Addition and Alternative Densification Routes
Matheus P Brambilla1,Alfonso Pulgar1, Rafael Zadorosny1
São Paulo State University (Unesp), School of Engineering, Campus Ilha Solteira - Physics and Chemistry Department
Abstract:
The ceramic superconductor YBCO has been extensively studied due to its remarkable properties, such as high critical temperature (~90 K) and high current density. However, its practical applications remain limited by the high cost of cryogenic refrigeration and the intrinsic brittleness of ceramic materials. The incorporation of metallic elements such as Ag and Al has been shown to enhance the mechanical strength of YBCO, mitigating cracks and fractures caused by internal stresses during thermal treatments and potentially optimizing its superconducting properties. These improvements, however, are typically observed only at low addition levels. While most studies employ conventional solid-state synthesis routes, this work explores an alternative approach using a one-pot chemical method to synthesize precursor solutions of YBCO with 0 and 5 wt% Ag. The resulting solutions were split into two batches: one processed via Solution Blow Spinning (SBS) to produce nanofibrous mats, and the other subjected to maceration to obtain a granular powder. Following heat treatment to form the Y123 phase, both morphologies were uniaxially pressed into pellets. The mechanical performance was evaluated through hardness mapping to assess the influence of Ag content and densification methodology. The results demonstrated that pellets derived from fibrous mats exhibited superior mechanical strength compared to those obtained from powder, with hardness increases of approximately 37% for pure YBCO and 17% for YBCO + 5 wt% Ag. However, they presented cracks perpendicularly to the pellet main axis. Based on these findings, additional samples were synthesized from fibrous YBCO + Ag with 0.5 and 20 wt% to further probe the effect of Ag content. The results revealed a saturation behavior, indicating that 5 wt% Ag is the optimal concentration for enhancing the mechanical properties of YBCO within the studied range.
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