Investigation of the temperature effect on the oxide layer formed on Alloy 182 in simulated PWR environment.

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Abstract

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.

Details

Original languageEnglish
Title of host publicationEUROCORR 2014 - EUROPEAN CORROSION CONGRESS
Place of PublicationFrankfurt, Germany
Publication statusPublished - 8 Sep 2014
EventEUROCORR 2014 - EUROPEAN CORROSION CONGRESS The annual event of the European Federation of Corrosion - European Federation of Corrosion (EFC), Pisa, Italy
Duration: 8 Sep 201412 Sep 2014

Conference

ConferenceEUROCORR 2014 - EUROPEAN CORROSION CONGRESS The annual event of the European Federation of Corrosion
CountryItaly
CityPisa
Period2014-09-082014-09-12

Keywords

  • Ni-based alloy, oxide layers, PWSCC

ID: 365217