Mechanical properties of (Ba0.4Sr0.4Ca0.2Fe12O19)x/(Bi1.6, Pb0.4)-2223 composite impacted in seawater

In the present work, the effect of adding Ba_0.4Sr_0.4Ca_0.2Fe₁₂O₁₉ hard nanoparticles and the immersion in seawater for different durations (0, 2, 6, 12, and 24 h) on the mechanical characteristics of the Bi, Pb-2223 superconductor phase were studied. A conventional solid-state reaction method was used to produce the (Ba_0.4Sr_0.4Ca_0.2Fe₁₂O₁₉)_x/(Bi_1.6, Pb_0.4)-2223 composites (0.00 ≤ x < 0.40 wt%). X-ray diffraction (XRD) confirmed the primary phase formation of the tetragonal (Bi_1.6, Pb_0.4)-2223. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) studies were also carried out to demonstrate the microstructural analyses of the samples during seawater immersion. Compared to the pure (Bi_1.6, Pb_0.4)-2223 phase, SEM and EDX verified the improvement of the adsorption of seawater elements upon adding the nanoparticles. This resulted in faster grain size reduction in the (Bi_1.6, Pb_0.4)-2223 phase than in the pure sample before immersion. Vickers microhardness (\(\:Hv\)) Measurements were performed for 30 s at room temperature, with applied stresses ranging from 0.49 to 9.80 N after immersion in the seawater for different durations (0, 2, 6, 12, and 24 h). For the sample with x = 0.04 wt%, \(\:Hv\) values enhanced with percentages of 67.72% and 98.44%, before and after immersion in seawater for 24 h, respectively. This suggests that the mechanical properties of the (Bi_1.6, Pb_0.4)-2223 phase were enhanced by a small addition of these nanoparticles and the salts of seawater adsorbed on the sample’s surface. The modified proportional sample resistance (MPSR) model offered the most accurate theoretical analysis in the plateau limit region, before and after seawater immersions, with a less than 5% variance. Furthermore, the incorporation of Ba_0.4Sr_0.4Ca_0.2Fe₁₂O₁₉ into the superconductor had a positive impact on several mechanical characteristics, including fracture toughness (K), yield strength (Y), and elastic modulus (E). All these mechanical parameter values followed the same trend, increasing with the increase in immersion time. However, they are at their height with the presence of 0.04 wt% of these nanoparticles. The toughness increased by 27.31% of the pure sample at this point. After that, when the immersion time rose from 0 to 24 h, this number increased by 42.59%.