Coiled electric wires have been developed for use in electromagnets that operate at high temperatures. Examples of such electromagnets could include the actuators in magnetic bearings in advanced gas turbines.
The starting wire material for a coil of this type can be either a nickel-clad, ceramic- insulated copper wire or a bare silver wire. The starting wire is either primarily wrapped with S-glass as an insulating material or else covered with another insulating material wrapped in Sglass prior to the winding process. A ceramic binding agent is applied as a slurry during the winding process to provide further insulating capability. The turns are pre-bent during winding to prevent damage to the insulation. The coil is then heated to convert the binder into ceramic.
In a test, coils of this type were mounted in a 12-pole magnetic bearing (see figure) and found to perform successfully at temperatures up to 1,200 °F (≈650 °C). Future development efforts will address the problems of increasing the thermal conductivity of the electrical-insulation materials to increase conduction of heat out of the coils, reducing the volumes of the coils, and fabrication of coils with various shapes (including square and other noncircular cross sections).
This work was done by Alan Palazzolo of Texas A&M University for Glenn Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to
NASA Glenn Research Center
Commercial Technology Office
Attn: Steve Fedor
Mail Stop 4–8
21000 Brookpark Road
Cleveland
Ohio 44135.
Refer to LEW-17164.

NASA Tech Briefs Magazine
This article first appeared in the August, 2002 issue of NASA Tech Briefs Magazine.
Read more articles from the archives here.