Role of microstructure in dielectric properties of thermally sprayed ceramic coatings

Thermally sprayed insulating ceramic coatings can be utilized in conditions where polymers are inapplicable. The coatings exhibit a special lamellar microstructure with interfaces and some defects (e.g. voids, cracks) in between. The aim of this study was to analyze the relationship between the micr...

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Published in2016 IEEE International Conference on Dielectrics (ICD) Vol. 2; pp. 1102 - 1105
Main Authors Niittymaki, Minna, Rytoluoto, Ilkka, Lahti, Kari, Metsajoki, Jarkko, Suhonen, Tomi
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.07.2016
Subjects
alumina
breakdown
ceramic
Ceramics
coating
Coatings
Conductivity
Dielectrics
Electric breakdown
microstructure
Permeability
permittivity
porosity
resistivity
spinel
spray
thermal
Thermal spraying
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Summary:Thermally sprayed insulating ceramic coatings can be utilized in conditions where polymers are inapplicable. The coatings exhibit a special lamellar microstructure with interfaces and some defects (e.g. voids, cracks) in between. The aim of this study was to analyze the relationship between the microstructural features and the dielectric properties of various thermally sprayed ceramics. The structural characterization of the ceramic coatings was made based on following properties: porosity, volumetric gas permeability and the characteristic size of crystalline lamella. High gas permeability of the coatings decreased the breakdown strength but similar effect cannot be seen in the DC resistivity and the permittivity results. Decrease of DC resistivity at high humidity did not correlate to microstructural properties; rather it is speculated to indicate the hydrophilic nature of the coatings. The characteristic crystalline domain sizes showed no clear correlation with the dielectric properties.
DOI:10.1109/ICD.2016.7547811