Abstract
Sealants are widely used in order to enhance the performance of porous thermally sprayed coatings, e.g. for electrical insulation or corrosion protection. In order to accomplish required properties, a good infiltration is necessary. The methods to assess the success of a sealing often rely on determining the infiltration depth by SEM or adding colour pigments to the sealer. In this study, a new approach for assessing the success of a sealing operation is investigated. The underlying assumption is that porous coatings are not gas-tight and by sealing them, the measurable gas flow can be reduced. Therefore, the success of a sealing operation may be assessed by comparing gas flows at defined conditions prior and subsequent to sealing. This hypothesis is investigated by coating special highly porous substrates with a wide range of coating porosities and thicknesses, sealing these coatings, comparing nitrogen flows at a defined pressure prior and subsequent to the sealing operation and correlating the measured changes of nitrogen flow with traditionally assessed infiltration depth and filling degree.
