Atmospheric Plasma Sprayed Forsterite (Mg2SiO4) Coatings: An Investigation of the Processing-Microstructure-Performance Relationship
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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.
Keywordscoefficient of thermal expansion dielectric coatings dielectric strength forsterite plasma-spray
The authors acknowledge valuable technical support from the Surface Technology Group members: J.-C. Tremblay for APS sample production, J. Sykes and D. DeLagrave for metallographic preparation, and M. Thibodeau for SEM imaging. The authors also acknowledge Tom Arbanas from Du-Co Ceramics, PA, USA for useful discussions on forsterite powder processing and for providing experimental batches of fine powders.
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