Study of anticorrosion and microwave absorption properties of NiZn ferrite pigments

Abstract

PurposeThe purpose of this paper is to report the electrochemical verification of anticorrosive properties of NiZn ferrites as pigments in protective coatings and evaluation of their microwave absorbing properties.Design/methodology/approachFerrites, represented by formula NixZn(1−x)Fe2O4, where x=0, 0.2, 0.4, 0.6, 0.8, 1.0, were synthesized using a ceramic method. The samples of ferrites were examined by X‐ray diffraction and SEM. Immersion tests in ferrite extracts, combined with electrochemical tests using techniques such as polarization curves, linear polarization and electrochemical impedance spectroscopy (EIS) were involved to determine the protective action provided by the ferrites. Epoxy coatings containing 10 vol.% of the ferrite were investigated using EIS. Experimental verification is provided of the microwave attenuation capability of coatings containing the investigated ferrites. Reflection loss, measured in the frequency range of 6.5‐15 GHz, exhibited maximum attenuation at a level of 8‐16 dB.FindingsThe results obtained suggest that NiZn ferrites possess active anticorrosive properties and support inhibition of the cathodic reaction by scale deposition at the metal substrate in an alkaline environment created by the pigments and the cathodic reaction. Additionally, they can serve as a microwave suppressor.Practical implicationsNiZn pigments can be used in coatings to serve simultaneously as an active anticorrosion, non‐toxic pigment and a material protecting against electromagnetic interference problems.Originality/valueThe paper provides information regarding the anticorrosive properties of NiZn ferrites as pigments for protective coatings and also microwave absorbing materials. An attempt was made to elucidate the potential mechanism of anticorrosive action of these pigments.