Electric field dependency of dielectric behavior of thermally sprayed ceramic coatings

Abstract

High temperature applications e.g. fuel cells require ceramic based insulation solutions instead of polymers. The aim of this paper was to characterize the dielectric properties of thermally sprayed ceramic coatings; especially the electric field dependency of AC and DC behavior of thermally sprayed ceramic coatings. One of the spinel samples and one of the alumina samples have quite similar lamellar microstructure which may partly explain their similar type of behavior in DC resistivity as well as in AC loss indexes at low frequencies. These two samples had smaller lamellar size than the other alumina and spinel samples which also had quite similar behavior of AC losses at low frequencies, respectively. In addition to the lamellar size and structure, also micro cracks in the coating microstructure are proposed to have an effect on the dielectric behavior and its electric field dependency.