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BEHAVIOUR OF POWDERED AND FLAKE MAGNETIC CORES AT TEMPERATURES UP TO 500 C
NAVAL ORDNANCE LAB WHITE OAK MD
The magnetic characteristics of seven high permeability 55-300 powdered and flake core materials were measured at 50 C temperature intervals up to 500 C. Three low permeability 13-22 Carbonyl iron E cores for higher frequency 100KC operation were also examined. Of the seven core materials tested for 100KC applications, Sendust powder showed the least irreversible change in permeability and eddy current coefficient after cycling to 500 C. None of the cores tested were stable for operation at elevated temperatures, although UQ curves showed that the Flakenol core was the most constant over the temperature range. The commercially available 2-81 Mo-Permalloy and Sendust powder cores were less constant. The magnetic characteristics of the high and low frequency carbonyl iron cores insulated with plastic binders were seriously degraded above 225 C. Although the cores tested were unstable above 250 C in varying degrees, the copper conductor material and its insulation appears to be the limiting factor for continuous 500 C operation.
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