Investigation of Atmospheric Plasma Sprayed Forsterite (Mg2SiO4) Coatings for High-Temperature Electrical Insulation Applications

Forsterite (Mg₂SiO₄) is used in a wide variety of electronic and telecommunication applications. It is also a suitable material for ceramic–metal seals e.g. in Solid Oxide Fuel Cell stacks. While APS can be used as a simple and cost effective means to produce dense forsterite layers on metallic substrates, the tendency of APS coatings to form amorphous phase has been prohibitive in wider acceptance of this technology especially for cases where either post-spray processing or thermal cycling may be required. In the present study, APS forsterite coatings based on newly developed “modified” forsterite powders were prepared with the goal to maximize the process economics and minimize the content of the amorphous phase. The microstructure and phase compositions were analyzed using SEM and XRD, respectively. The results show that the feedstock powder characteristics have a strong influence on the phase composition, CTE and dielectric properties of the coatings.