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Oxidation Behaviour of Sanicro 25 (42Fe22Cr25NiWCuNbN) in O-2/H2O Mixture at 600 degrees C

Luciana Intiso (Institutionen för teknisk fysik, Mikroskopi och mikroanalys) ; Lars-Gunnar Johansson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Sead Canovic (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; S. Bellini ; Jan-Erik Svensson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Mats Halvarsson (Institutionen för teknisk fysik, Mikroskopi och mikroanalys ; Institutionen för teknisk fysik, Materialens mikrostruktur )
Oxidation of Metals (0030-770X). Vol. 77 (2012), 5-6, p. 209-235.
[Artikel, refereegranskad vetenskaplig]

The present study investigates oxidation at 600 A degrees C of alloy Sanicro 25 (42Fe22Cr25NiWCuNbN) in dry and wet O-2 environments. The exposure time was 1-168 h. The oxidized samples were analyzed by grazing incidence X-ray diffraction, glow discharge optical emission spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. Alloy Sanicro 25 showed protective oxidation behaviour under the present conditions. Initially, a thin and smooth corundum-type single layer base oxide formed, featuring a Cr-rich bottom part and a Fe-rich top. With time, double-layered oxide nodules form consisting of inward- and outward-growing parts. Below the oxide scale a 100-200 nm thick oxidation-affected zone formed in the alloy, which was depleted in Cr and enriched in Ni. In this region the chromium carbides and copper-rich particles present in the bulk alloy were dissolved. In O-2 + H2O environment, chromium volatilized from the surface, causing the chromium content of the oxide to be lower than after oxidation in dry O-2. However, under present experimental conditions, the Cr depletion of the scale was not enough to trigger accelerated corrosion of the alloy.

Nyckelord: Oxidation, Water vapour effect, Chromia evaporation, Chromia former, Sanicro 25, high-temperature oxidation, water-vapor, chromium evaporation, steam, oxidation, flow-rate, steel, oxides, environments, scales, oxygen



Denna post skapades 2012-06-07. Senast ändrad 2017-10-03.
CPL Pubid: 158631

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik, Mikroskopi och mikroanalys (2005-2012)
Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)
Institutionen för teknisk fysik, Materialens mikrostruktur (2012-2015)

Ämnesområden

Materialteknik

Chalmers infrastruktur

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