Comparison of Ceramic Insulation Coatings via Impedance Spectroscopy

Abstract

Alumina is often used for electrical insulation. However, different material systems promise to increase the insulation due to their material characteristics. Because of the process properties including high cooling rates, thermally sprayed coatings generally differ from sintered material, which also effect the electrical properties. Within this study, different thermally sprayed coatings are analyzed via impedance spectroscopy to evaluate the capacitive and the electrical insulation behavior. Besides comparing the frequency-dependent resistance, equivalent circuit diagrams were used to calculate the relative permittivity of the coatings. X-ray diffractograms reveal the phase stability of the coatings during thermal spraying. X-ray diffraction was additionally conducted to classify the systems and the respective effects. In particular, the investigated mullite-based coatings exhibit slightly increased impedance values compared to conventionally used alumina-based coating systems.

Impedance Measurement and Demonstrator Tests of Developed Thermally Sprayed and Sealed Coating Systems for Bearing Applications

“…To increase the electrical insulation performance of thermally sprayed and sealed coating systems for bearings in electrical engine train drives, mullite was chosen as an alternative material to the standard alumina coatings. Mullite showed increased impedance values compared to other ceramic coatings [ 15 ] and was therefore further investigated.…”

“…In a previous work, we compared different thermally sprayed ceramic coating materials regarding their dielectric behavior. [ 15 ] To prevent the influence of the substrate and interface, the coatings were detached from substrate. Alumina as standard electrical insulation material for thermal spraying was compared to mullite and spinel.…”

Achieving High Dielectric Constant in γ-Al2O3-rGO Nanocomposite Prepared by Microwave-Assisted Co-Precipitation Method

“…The dielectric constant of commercial alumina is currently approximately 7. 8,9 However, this value needs to be improved because a higher dielectric constant is necessary for the future creation of dielectric capacitors.Utilizing graphene and graphene hybrid has been proven to be one of the most efficient ways to increase the surface area, mechanical stability, and Dielectric constant of electrochemically active metal oxides for dielectric capacitor applications. 2 Various phases of alumina are different in physical properties, such as density, dielectric constant, and energy gap.…”