Development of Ba-hexaferrite coatings for electromagnetic wave absorption applications

In this research, Ba-hexaferrite coatings for electromagnetic wave absorption applications were deposited by thermal spraying. A suitable powder feedstock was manufactured by blending a BaCO3 + Fe2O3 mixture, which was then agglomerated by spray-drying. The agglomerates were processed by air plasma spraying (APS) without any further treatment or were heat-treated and reactively-sintered to stoichiometric Ba-hexaferrite prior to spraying. As-sprayed coatings were analyzed by Raman spectroscopy and X-ray diffraction (XRD). Whereas the deposition of untreated agglomerates did not result in adequate amounts of crystalline Ba-hexaferrite in the coatings, the APS processing of reactively-sintered agglomerates led to a high content of Ba-hexaferrite and similar magnetic properties to those of Ba-hexaferrite bulk materials.