Effect of surface passivation of Inconel 690 on oxidation in primary circuit conditions

摘要

Corrosion of Inconel 690 occurs in steam generators of Pressurised Water Reactors and is partly responsible for the activity of the primary circuit surfaces. The aim of the present study is to reduce the release of corrosion products by promoting the formation of a barrier film at the surface of Inconel 690. Several surface treatments have been tested, by means of a corrosion test carried out in a loop simulating primary water conditions: pickling, electropolishing, aqueous oxidation with zinc or oxygen, gaseous oxidation, pack-CVD chromisation and ion nitriding. The results (oxide thickness or weight variation, quantity of released metal and surface morphology) show the particularly good corrosion resistance of the following treatments: electropolishing and conventional gaseous oxidation.