Coated ferromagnetic particles and composite magnetic articles thereof

A method for making a coated ferromagnetic particle, said method comprising the steps of:

• a. providing an uncoated ferromagnetic core;
• b. providing a coating material consisting essentially of a polymer selected from the group consisting of polyorganosiloxanes, polyorganosilanes, and mixtures thereof;
• c. encapsulating said uncoated ferromagnetic core with said coating material;
• and
• d. thermally treating said coating material so as to convert said coating material into a residue;
• to produce said coated ferromagnetic particle.

A method for making a coated ferromagnetic particle, said method comprising the steps of:

• a. providing an uncoated ferromagnetic core;
• b. providing a coating material comprising a polymer selected from the group consisting of polyorganosiloxanes, polyorganosilanes, and mixtures thereof;
• c. encapsulating said uncoated ferromagnetic core with said coating material comprising said polymer;
• and
• d. thermally treating said coating material so as to convert said coating material into a residue;
• to produce said coated ferromagnetic particle, wherein said coating material has a weight in a range from about 0.05 weight percent to about 1 weight percent of a total weight of said ferromagnetic core and said coating material.

A method for producing a composite magnetic article, said method comprising the steps of:

• a. providing uncoaated ferromagnetic particles;
• b. providing a coating material consisting essentially of a polymer selected from the group consisting of polyorganosiloxanes, polyorganosilanes, and mixtures thereof;
• c. encapsulating each of said uncoated ferromagnetic particles with said coating material to produce encapsulated ferromagnetic particles;
• d. subjecting said encapsulated ferromagnetic particles to a compaction to form a compact of a desired shape;
• and
• e. subjecting said compact to an annealing treatment;
• to produce said composite magnetic article, wherein said composite magnetic article comprises a plurality of coated ferromagnetic particles wherein each particle comprises a ferromagnetic core and a coating, said coating consisting essentially of a residue resulting from a thermal treatment of said coating material.

A method for producing a composite magnetic article, said method comprising the steps of:

• a. providing uncoated ferromagnetic particles;
• b. providing a coating material comprising a polymer selected from the group consisting of polyorganosiloxanes, polyorganosilanes, and mixtures thereof;
• c. encapsulating each of said uncoated ferromagnetic particles with said coating material comprising said polymer to produce encapsulated ferromagnetic particles;
• d. subjecting said encapsulated ferromagnetic particles to a compaction to form a compact of a desired shape;
• and
• e. subjecting said compact to an annealing treatment;
• to produce said composite magnetic article, wherein said composite magnetic article comprises a plurality of coated ferromagnetic particles wherein each particle comprises a ferromagnetic core and a coating, said coating comprising a residue resulting from a thermal treatment of said coating material comprising said polymer, wherein said coating material has a weight in a range from about 0.05 weight percent to about 1 weight percent of a total weight of said ferromagnetic core and said coating material.