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:
Chromium rich, nickel based alloys Haynes 230 and Inconel 617 are candidate materialsfor the primary circuit and intermediate heat exchangers (IHX) of (Very)-High TemperatureReactors. The corrosion resistance of these alloys is strongly related to the reactivity of chromiumin the reactor specific environment (high temperature, impure helium).At intermediate temperature – 900°C for Haynes 230 and 850°C for Inconel 617 – the alloys underinvestigation are likely to develop a chromium-rich surface oxide scale. This layer protects from theexchanges with the surrounding medium and thus prevents against intensive corrosion processes.However at higher temperatures, it was shown that the surface chromia can be reduced by reactionwith the carbon from the alloy [1] and the bare material can quickly corrode. Chromium appears tobe a key element in this surface scale reactivity. Then, quantitative assessment of the surfacerequires an accurate knowledge of the chromium activity in the temperature range close to theoperating conditions (T ≈ 1273 K).High temperature mass spectrometry (HTMS) coupled to multiple effusion Knudsen cells wassuccessfully used to measure the chromium activity in Inconel 617 and Haynes 230 in the 1423-1548 K temperature range. Appropriate adjustments of the experimental parameters and in-situcalibration toward pure chromium allow to reach accuracy better than ± 5%.For both alloys, the chromium activities are determined. Our experimental results on Inconel 617are in disagreement with the data published by Hilpert [2]. Possible explanations for the significantdiscrepancy are discussed
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.595-598.975.pdf
