A VALUABLE VIEW ON EVALUATION OF GENERAL MECHANICAL PERFORMANCES PERTAINING TO Bi-2223 SUPERCONDUCTING CERAMICS WITH VANADIUM ADDITION

Abstract

In this research, our scientific group investigates the effect of vanadium addition in the Bi-2223 superconducting matrix on the general mechanical performance features by the help of experimental microhardness measurements conducted by a small indenter between the well-defined stress loads of 0.245 N and 2.940 N. Moreover, we determine the key mechanical design parameters including the elastic moduli with the hardness, stiffness coefficients, fracture toughness, yield strength, brittleness index and its opposite behavior (ductility) in the applied test loads given using the experimental data deduced from the microindentation tests. According to the experimental findings, it is oberved that the presence of vanadium content in the Bi-2223 crystal structure surpasses seriously the general mechanical performance and related parameters due to the degradation in the quality of grain boundary couplings, crystal structure and basic structural quantities as a consequence of the increment in the structural problems, permanent plastic deformations, crack-producing flaws and dislocations. In other words, the augmentation of vanadium compounds in the Bi-2223 superconducting lattice brings about the considerable enlargement in the responsibility to the static indentation loads. Namely, the sensitive level to the applied loads increases rapidly with the vanadium concentration. We also search the variation of graphs between the Vickers hardness parameters and applied test loads. In this respect, all the materials prepared in this work exhibit the standard ISE (indentation size effect) characteristics but within the decrement trend as the vanadium content level increases. In more detail, the impurity atoms damage harshly the ISE feature of Bi-2223 type-II superconducting ceramics. Additionally, we discuss the change of plateau limit regions coincided with the permeant artificial structural problems in the graphics. The vanadium leads to shorten the applied test load values for the plateau limit regions of Bi-2223 materials, stemmed from the enhancement the general structural problems. To conclude, the vanadium inclusions are ploughed to improve the general mechanical performance features and key mechanical design parameters.