Dependence of General Mechanical Properties of Bi-2212 Ceramics on Calcium Oxide

Abstract

In this study, we investigated the role of calcium oxide (CaO) impurity addition and applied micro-indentation test loads on some mechanical performance parameters including elastic moduli (E), shear (G) modulus and resilience (Ur) of Bi2.1Sr2.0Ca1.1Cu2.0Oy ceramics using Vickers hardness test measurements. The tests were conducted in test forces ranges from 0.245 N to 2.940 N. Additionally, experimental findings reveal the relationship between Vickers results and test forces applied, and specifically identify the impact of Ca ion impurity on the elastic modulus for Bi-2212 ceramics. All experimental findings indicated a strong dependence of the examined mechanical performance quantities on both the loads applied and the amount of calcium oxide impurity addition. As the level of calcium impurity addition increased in bulk Bi-2212 ceramic compounds, it was noted that mechanical performances are systematically deteriorated due to an increase in microvoids, strains, prevalent defects, bonding problems, and crystallinity faults based on interaction between adjacent layers of ceramics. Furthermore, increasing the applied test force damaged the mechanical performances of Bi-2212 ceramics due to their granular structure. Thus, it was indicated that the pure sample has the best crystal quality while the Bi-2212 ceramic prepared with the maximum CaO addition amount of x=0.1 has the maximum crystal structure problems. In this regard, the former ceramic exhibited much stronger mechanical performance quantities compared to the other prepared ceramics. In other words, the pure ceramic material showed the least response and sensitivity to the microindentation test load. In summary, the idea of adding calcium oxide impurity fails to improve the mechanical performance, durability of the tetragonal phase, and stabilization of the Bi-2212 superconducting system.