Controlled over-pressure sintering process of Bi2223 wires

Abstract

We studied the influence of the high isostatic pressure and critical current density in Bi2223 long length wires. Heat treatments of Bi2223 wire were carried out using controlled over-pressure sintering process. The controlled over-pressure sintering process allows Bi2223 wires to have higher Ic by more than 30%, because the process increase the relative density up to almost 100% resulting in higher phase purity, higher grain alignment and better grain connectivity than those made with a conventional normal pressure sintering process. Densification of the Bi2223 wire prevents liquid nitrogen penetration during long term exposure to liquid nitrogen of it for use in power cable applications. The ballooning, which the trapped nitrogen expands and forms after Bi2223 wire was warmed to room temperature, does not occur in the controlled over-pressure sintering processed wire. These high performance levels in long length Bi2223 wires have enabled commercial level products and projects such as power cables, magnets and many others.