Ceramics-Silikáty 52, (2) 85 - 89 (2008) |
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USE OF EMANATION THERMAL ANALYSIS IN THE MICROSTRUCTURE DIAGNOSTICS OF ALUMINA COATINGS
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Balek Vladimír 1,2, Beneš Martin 2, Šubrt Jan 3
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1 Nuclear Research Institute Řež, plc., 250 68, Řež, Czech Republic
2 Research Center Řež, Ltd., 250 68, Řež, Czech Republic
3 Institute of Inorganic Chemistry, AS CR, 250 68, Řež, Czech Republic
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Keywords: Alumina coatings, Emanation thermal analysis, SEM, Microstructure irregularities, Cracks healing
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Emanation thermal analysis (ETA), based on the radon release measurements, was used to characterize the microstructure
development of alumina coatings on heating. The alumina coatings were deposited on EUROFER' 97 steel surface by using
the filtered vacuum arc technique. Healing of microstructure irregularities that served as radon diffusion paths in the alumina
coatings was characterized as a decrease of the radon release rate in the range 300-700°C. The healing of surface microcracks
observed by SEM micrographs on the alumina coating sample was characterized as the break on the temperature
dependence of radon release rate in the temperature range 430 -660°C. From the ETA results it followed that healing of the
microstructure irregularities in the range of 300-700°C was depending on the conditions used for the alumina coatings preparation.
A higher intensity of this process can be expected with the alumina coating of 4 µm thickness in comparison with the
alumina coating of 0.5 µm thickness. |
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