Abstract:
High-permeability, low-core-loss soft magnetic composite materials, compositions containing the same, and methods for making the same are described. These magnetic materials are made by forming fiber or flake shaped particles from a ferromagnetic material, annealing the particles, and then coating an insulating material on the particles. These particles can then be compacted to form an article that has high permeability, high saturation, low core loss, and is a suitable replacement for laminations in various applications, such as motors.
Abstract:
Ferromagnetic particles with a high-temperature and thermally stable insulating coating are described. The ferromagnetic particles are first coated with a thin layer of a high permeability metal (nickel) by an electroless plating process. The deposited metal layer is then oxidized by controlling the time and temperature while heating the coated particles in an oxygen atmosphere. This process develops a thin and uniform layer of metal oxide on the ferromagnetic particles. The controlled oxidation of the coating helps encapsulate the particles with a thermally stable and electrically non-conducting layer. These particles can then be compacted and then annealed above 500 degrees Celsius to relieve the stresses introduced in the shaping, thereby obtaining articles with a high permeability and low magnetic loss.
Abstract:
Soft magnetic composites having a high compressibility and a high permeability are described. These two characteristics are obtained by combining high compressibility iron powder to high permeability powders. The iron powder is of a high compressibility and in a size range and proportion that results in a powder mass amenable to compaction by industrially viable and cost-effective compaction process such as uniaxial cold compaction. The high compressibility iron powder helps achieve high relative density and also allows easy path for the passage of magnetic flux.