Properties of high density magnetic composite (HDMC) fabricated from iron powder coated with new type phosphate insulator

A powder magnetic core was developed using a novel warm compaction method using die wall lubrication with lithium stearate. The powder magnetic core, which was named HDMC (high density magnetic composite), has high magnetic flux density and high strength. However, the HDMC, which was fabricated from iron particles coated with a phosphate glass insulator, had large eddy current loss at high frequency because the resistivity was small. To address this deficiency, a phosphate glass insulator with Sr²⁺or Y³⁺ was developed which was found to have high resistivity in keeping high magnetic flux density and strength of the HDMC.