Sendust Flake- A New Magnetic Material for Low-Frequency Application

A high permeability, low-loss core was prepared by compacting Sendust flakes, which were produced by warm rolling Sendust powder. Sendust, a brittle magnetic alloy of iron, silicon, and aluminum, was discovered by the Japanese in 1936 and is used extensively by them in cast and powder form. The low permeability values (70-80) of Sendust powder cores precluded their acceptance in this country to any extent. The improved magnetic properties of the new flake cores, called Flakenol I, make them an attractive nonstrategic substitute for applications which now require powdered high nickel alloys. The permeability values as measured on compacts of this newflake core ranged from 150-280, with electrical losses as low as present powder cores. The very low eddy-current loss coefficient value measured on Sendust flake cores indicates their usefulness at higher frequencies than possible for present high permeability powder cores. The flake cores, which have a negative temperature coefficient of permeability, were stabilized by the addition of Alfenol flake material. The comparatively simple techniques for processing Sendust flake cores from the cast alloy are described, along with the factors which most influence their ultimate magnetic characteristics.