Depletion Sensor for Protective High Temperature Coatings

SPP 1299

Bild Forschungsprojekt

Hochtemperaturofen in Betrieb

Period: 2007-04-01 to 2013-03-31
Funder: German Research Foundation (DFG)
Project Manager: Dr. Krasimir Aleksandrov
Research Group: High Temperature Materials

At high temperatures metallic or intermetallic Cr- and/or Al-rich diffusion or overlay protective coatings are applied on metallic substrates, as high temperature alloys, Ni-base alloys in order to minimize high temperature corrosion. It results from the presence of various gaseous species in most high temperature environments of industrial interest. Protection against corrosion is achieved by the formation of a continuous Cr2O3 and/or Al2O3 scale, which serves as a barrier between the underlying metal and the environment. After long operating periods progressive scale formation and interdiffusion between the coating and the substrate leads to the depletion of the scale-forming elements, i. e. Cr or/and Al. The dropping of their concentration under a critical value results in accelerated corrosion and quick breakdown of the component. To date for measurement of the depletion only destructive methods are available.
The task of the project is the development of a depletion sensor for protective high temperature coatings. As a sensor, coatings made from a magnetic material will be used. This will provide in-situ assessment of the depletion and a non-destructive method for its detection. Prediction of the remnant-life of the units with significant economic impact for both, producer and operator of the facility will be possible.

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