On the dielectric behavior of annealed plasma sprayed forsterite and alumina coatings

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Proceedings titleProceedings of the International Thermal Spray Conference 2014 (ITSC)
ConferenceThermal Spray 2014, May 21-23, 2014, Barcelona, Spain
Pages184189; # of pages: 6
AbstractAtmospheric plasma spray (APS) is an efficient technique for depositing high performance dielectric coatings at a low cost, with high deposition rate and on complex-shaped parts. Due to its availability, low price, ease to spray and good dielectric properties, alumina (Al2O3) is a very common choice of material for insulating applications. However, the coefficient of thermal expansion (CTE) of alumina does not represent the best match for the CTE of most metallic substrates hence alternative high CTE ceramic materials are of interest. We report on the microstructural and electrical properties of a dense high CTE forsterite (Mg2SiO4) coating deposited by APS. Annealed forsterite coatings' microstructure and dielectric properties are compared to that of annealed alumina coatings. The ceramics' electrical properties were evaluated by performing impedance measurements on as-sprayed coatings and coatings exposed to different annealing temperatures. We show that both materials exhibit important degradation after exposure to a threshold temperature. An equivalent electrical model is used to extract relevant coating properties such as resistivity and dielectric constant. The coating electrical degradation mechanisms are discussed.
Publication date
AffiliationAutomotive and Surface Transportation; National Research Council Canada
Peer reviewedYes
NRC numberNRC-AST-147059
NPARC number21272357
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Record identifierc4c391bc-db6a-4986-bab8-eb744957550f
Record created2014-11-24
Record modified2016-05-09
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