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 granulometries. The microstructural and porosity characteristics of the coatings associated with the spray conditions employed were assessed via scanning electron microscopy (SEM) and image analysis. 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 and impedance spectroscopy measurements. The electrical properties obtained were correlated with the microstructural characteristics and a performance comparison between forsterite and other dielectric coatings is presented.