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Conference Article: Ceramic coatings for HTR graphitic structures

Abstract

The main intention of ceramic coatings is to realize a corrosion resistance for graphitic structures in the temperature range of 450 to 1600 deg. C. To obtain a wide basis for producing these coated structures different graphite qualities were tested. For the production of ceramic coatings on silicon carbide basis different methods were applied. Industrial coatings were successfully produced with the slip casting method. Using chemical vapour deposition methods ceramic coatings were produced with excellent corrosion resistance. At the Technical University in Aachen and the Research Center in Juelich a special coating method being a combination of silicon infiltration and slip casting method was successfully developed for this kind of application. To characterize the produced coatings a lot of corrosion tests were carried out simulating hypothetical accident conditions in high temperature reactors (massive water and air ingress into the core) in the temperature range of 500 to 1500 deg. C. The gravimetrically measured reaction rates in air by equivalent air velocities amount to R <= 1 mg/cm²h. For simulated water ingress accidents the maximal reaction rates (T=800 deg. C) are 0.2mg/cm²h. these results show, that a ceramic coating leads to very high corrosion resistance for graphitic core materials.

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Reference:

Technical committee meeting on response of fuel, fuel elements and gas cooled reactor cores under accidental air or water ingress conditions. Beijing (China). 25-27 Oct 1993

International Atomic Energy Agency, Vienna (Austria)

IAEA-TECDOC--784, pp:120-124