||Since the discovery of high-temperature superconductors in 1986, a large
amount of research has gone into the development of superconducting materials
and the manufacturing of superconducting tapes. Superconducting tape can carry
extremely high current densities compared with conventional conductors. As such,
superconductors are expected to be used increasingly for powerful magnets in
hospital scanners, coils for energy storage and cables for power transmission. The
first experimental cable for power transmission, supplying 150.000 private homes,
was installed in Copenhagen in May 2001.
Cables like the above mentioned are based on superconducting tape
consisting of ceramic fibres (filaments) in a metal matrix. The manufacturing
process used to create these tapes is called "Powder-In-Tube" method (PIT). This
method involves pouring a ceramic powder into a metal tube, which is drawn into a
long thin wire. The wire is then cut into shorter pieces and packed into yet another
metal tube. This tube is then drawn into a long multifilament wire with a diameter
of approximately 1 mm. Such a wire can contain hundreds filaments. The wire is
then rolled flat to form a tape with a cross-section of approximately 4.0x0.2 mm
and a length up to 1km. Finally, the tape is heat-treated and pressed to achieve
the desired superconducting properties.
In January 2001 Japanese researches discovered that the hitherto
disregarded and simple material MgB2 was superconducting at 39K. As such,
MgB2 is not a true high-temperature superconductor; however its critical
temperature is substantially higher than that of traditional low-temperature
superconductors. This, combined with other properties, makes MgB2 very
promising for superconducting applications.
In this work the process parameters for manufacturing MgB2
superconductors have been studied. This work implies:
* A study of the annealing requirements to manufacture single
* Testing of different multifilament assemblies configurations.
* Testing of different reduction/annealing schedules to draw down
The present work contributes to better understanding of the MgB2
superconductor wire drawing process and the behaviour of the implied materials.