ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The aim of the present work is to investigate the effect of Lanthanum surface addition onthe oxidation behaviour of the AISI 304 stainless steel, in air, at 1000°C. The in situ X-raydiffraction (XRD) analyses on the blank steel reveal that after the first 10h oxidation, a change inthe structural composition of the oxide scale occurs. During the first ten hours oxidation an initialgrowth of chromia and Mn1,5Cr1,5O4 is observed. After 10 h oxidation, chromia is not detectedanymore and iron-containing oxides such as hematite (Fe2O3) and iron chromite (FeCr2O4) areobserved in the outer part of the scale. With blank AISI 304 specimens, the iron-containing oxidesare generally not very protective and show severe spallation during cooling to room temperaturedue to thermal stresses. They do not allow a good adherence of the corrosion layer under thermalcycling. On the Lanthanum coated AISI 304 Stainless Steel the oxidation rate is 10 times lower. Insitu XRD analyses show the absence of iron containing oxides. It reveals the formation of a fineconvoluted Cr2O3 layer associated with the formation of the mixed oxides Mn1,5Cr1,5O4 and LaCrO3.LaCrO3 is found to be located at the oxide/steel interface. Our results show that, even though thescale formed under isothermal conditions is not composed of iron containing oxides, Lanthanumsol-gel coating does not prevent spallation during thermal cycling at 1000°C
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.595-598.733.pdf
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