Effects of binder addition on the mechanical properties of bulk Y-Ba-Cu-O superconductors

We studied the effects of binder addition on the mechanical properties of bulk Y-Ba-Cu-O superconductors. We prepared YBa2Cu3Oy, Y2BaCuO5 powders and polyvinyl alcohol mixed with water as a binder. These raw materials were mixed, and the binder-added powders were pressed into pellets. The hardness of the green compacts with binder is higher than that without the binder. However, the hardness of green compacts with 8% binder is the same as that with 4% binder. The maximum compression strength of the precursor with binder is higher than that without binder. Equally, the maximum strength of the green compacts with 8% binder is higher than that with 4% binder. The differential thermal analysis measurements showed that the exothermic reaction due to the decomposition of the organic binder started at 550 °C and gradually proceeded with further heating. After de-binder treatment, BaCO3 powders were produced on the green compacts. The green compacts were subjected to melt-processing. We also measured trapped magnetic fields of binder-added bulk Y-Ba-Cu-O superconductors with a Hall probe scanning device. Trapped magnetic field of the bulk added with 4% is higher than that of the binder-free bulk. Hence, Y-Ba-Cu-O bulk with suitable amount of binder shows good influence for mechanical strength and trapped magnetic field.