NDTnet 1998 Aug, Vol.3 No.8

Abstract

The discovery of high-temperature Superconductivity in 1986 by Bednorz and Mueller signified a "quantum-leap" in the technology of superconductivity. Up to then it was necessary to cool "low temperature superconductor" - materials to nearly absolute zero, using liquid helium, before they would lose their electrical resistance. This is now possible for "high-temperature superconductors" at much elevated temperatures, using liquid nitrogen.

The significance is, that suddenly technical solutions to industrial applications become feasible, which up to now were either too expensive or too involved. This applies also to SQUID sensor technology (Superconducting Quantum Interference Device), the most sensitive of the currently known magnetic field measuring devices. Their application in sensor technologies for eddy current testing was repeatedly discussed, but always failed in practice. due to the costly cooling technology, along with other hurdles.

Several pioneers of the new SQUID technology recently initiated a new R&D project, together with an eddy current equipment manufacturer, two aircraft companies and a specialist in cooling technology. The goal: Examine and evaluate the basic applicability of this new technology to eddy current testing in the aircraft industry. It is reasonable to apply this technology first to this branch of industry, since aircraft are subjected to high safety standards. They are tested carefully and systematically and exhibit a high degree of complexity, which often pushes NDT to its limits.

The first step in qualifying eddy current test systems using SQUID technology is to demonstrate that these systems can operate in the laboratory, independent of orientation, without shielding, and that they can operate in typical aircraft maintenance environments without major difficulties. This goal has been achieved quite satisfactorily. The second goal to be attained is that these systems can be used directly on aircraft, since the testing tasks naturally will have to be performed on location. Solutions to this task are now available. The third and most difficult step is, however, to achieve a higher degree of detectability of defects under the aforementioned conditions. First results have shown that even this goal can be met. The last step, which however can no longer be a part of the R&D project, is the development of a compact, cost-effective industrial system.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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