Abstract
Silica-based composite coatings with dispersion of glass or alumina granular particles were fabricated on n-type Yb0.3Co4Sb12 and p-type CeFe3CoSb12 skutterudite (SKD) thermoelectric (TE) materials using hybrid silica sol as raw material which was synthesized through hydrolysis and condensation under acid condition process. The dispersion of either glass particles or alumina particles restrained the formation of micro-cracks during solidification due to relaxing tremendous cohesive stress in the gel. The high temperature stability for both the coating materials and the coated skutterudite matrix were investigated through thermal aging at 873K in vacuum. Inter-diffusion of Sn from glass toward SKDs and Sb from SKDs toward coating layer was observed in the glass particle dispersed silica composite coating, which resulted in the failure of protecting function of the coating layer. In the alumina particle dispersed silica coating, neither diffusion nor reaction between the coating and SKD materials was observed after thermal aging at 873K. The sublimation of antimony is suppressed in the SKDs overlaid by the alumina dispersed silica composite coating.
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