Antioxidation and electromagnetic properties of Co-coated hollow carbonyl iron particles by electroless plating method

Co-coated hollow carbonyl iron particles were prepared by a method combining pitting corrosion and electroless plating. The comparison of morphology from images of SEM, phase composition, magnetic property and apparent density of initial and processed particles before and after heat treatment demonstrated the low density and high antioxidation properties after processing, which proved Co coating acts as a protection layer. The complex permittivity and complex permeability of raw carbonyl iron, hollow carbonyl iron and Co-coated hollow carbonyl iron particles were measured and the mechanisms of varying electromagnetic parameters were analyzed. And the electromagnetic microwave absorption properties of raw carbonyl iron, hollow carbonyl iron and Co-coated hollow carbonyl iron particles were investigated in the frequencies during 2–18 GHz. The band width below −10 dB could reach 4 GHz and the minimum of reflection loss value could reach to −19.5 dB for the Co-coated hollow carbonyl iron particles, which can maintain a good microwave absorption property.