Insulated iron-base powder for soft magnetic applications

摘要

The present invention relates to ferromagnetic powders with an electrically insulating layer on iron particles intended for the manufacture of components having improved soft magnetic properties at low and medium frequencies. The invention comprises an iron powder coated with a dielectric insulating layer comprising boron bearing compounds to form an insulated ferromagnetic powder. The present invention also relates to a method of making these insulated ferromagnetic powders. The present invention further relates to a method of synthesizing a product made from insulated ferromagnetic powders via a post-heat treatment at a moderate temperature (300° C. to 700° C.), to form a glass-like coating which acts as an electrical insulator. A preferred embodiment of the present invention is obtained when small amounts of alkali bearing compounds are added to the precursors to modify the coating chemistry and significantly increase the electrical resistivity after heat treatment.

主权项

1. An insulated ferromagnetic powder comprising:
an iron base powder; and a borate-based dielectric insulating layer comprising a boron-bearing compound and an alkali glass modifier, said alkali glass modifier comprising an alkali-bearing compound that is different than said boron-bearing compound, wherein said iron powder has iron particles between 5 μm and 750 μm in size and said dielectric insulating layer has a thickness of less than 100 nm as determined through depth profiling of the boron element using XPS measurements and the argon ion beam etching technique.