Atmospheric Plasma Sprayed Forsterite (Mg2SiO4) Coatings: An Investigation of the Processing-Microstructure-Performance Relationship

Evaluating and understanding the relationship between processing, microstructure and performance of a dielectric coating is essential for its practical usage and reliable application. In this study, the role of the powder feedstock on the properties of atmospheric plasma sprayed forsterite (Mg₂SiO₄) dielectric coatings was investigated by using different forsterite powder cuts. The coatings’ microstructural and porosity characteristics associated with the spray conditions employed were assessed via scanning electron microscopy (SEM), image analysis and X-ray microtomography (XMT). The phase composition of the coatings was studied via X-ray diffraction and their crystallinity index determined. The electrical insulating characteristics were investigated using the dielectric breakdown test, four probe technique and impedance measurements. The obtained electrical properties were correlated with the microstructural distinctiveness. Ultimately, a performance comparison between forsterite and other dielectric coatings tested in similar conditions is presented.