Ni-based alloys show a peak in SCC susceptibility at a certain temperature and hydrogen concentration. This peak is related to the electrochemical condition where the Ni to NiO transition takes place. One assumption is that the oxide layer at this condition is not properly developed and so the material is not optimal protected to SCC. Therefore the oxide layer formed on Alloy 182 is investigated as a function of the water chemistry and temperature. The main aim of this work is to correlate the behaviour and composition of the different oxide layers formed in high temperature water. Exposure tests have been performed with Alloy 182 and Ni coupons in a PWR environment as a function of temperature for a dissolved hydrogen concentration of 35 cc/kg. The temperature ranged from 300 to 345°C as in this range the Ni/NiO transition is located based on thermodynamic calculations. Post-test analysis of the formed oxide layers have been carried out by Scanning Electron Microscopy and Energy Dispersive Spectroscopy. The first results showed that there is a large difference between the low (300°C) and high (345°C) exposure temperature w.r.t. the oxide layer morphology.
|Title of host publication||EUROCORR 2014 - EUROPEAN CORROSION CONGRESS|
|Place of Publication||Frankfurt, Germany|
|State||Published - 8 Sep 2014|
|Event||EUROCORR 2014 - EUROPEAN CORROSION CONGRESS The annual event of the European Federation of Corrosion - European Federation of Corrosion (EFC), Pisa|
Duration: 8 Sep 2014 → 12 Sep 2014
|Conference||EUROCORR 2014 - EUROPEAN CORROSION CONGRESS The annual event of the European Federation of Corrosion|
|Period||2014-09-08 → 2014-09-12|