Modified heat-treatment process of precursor powders for Bi-2212 tapes preparation

Abstract

The physical sorption instrument, Carbon and Sulfur by combustion and infrared detection, Hydrogen by combustion and infrared detection and FTIR were employed to study the adsorption behavior of the Bi-2212 powders in air. The results showed that the chemical adsorption of both CO2 and H2O from environment would take place during the exposure in air and the reaction rate can be greatly accelerated by the grinding. The adsorption mechanism was analyzed based on the characterization of the crystal structure of Bi-2212 superconductor. Meanwhile, combining with the practical preparation process of Bi-2212 tapes, the formation mechanism of both macroscopic bubble and micro porosity in the traditional Bi-2212 tapes during sintering process was raised. Base on these analyses, the high temperature heat-treatment and vacuum sinter process were employed to decrease both the adsorption gas and gas within Bi-2212 particles to avoid the macroscopic bubble and micro porosity, and enhance the transport properties of Bi-2212 final tapes.