Influence of nickel on the behaviour of superferritic 290 Mo alloys in sulphuric and hydrochloric acid media: XPS, AES and electrochemical studies
✍ Scribed by M. Traisnel; M. Elachab; L. Gengembre; J. M. Leroy
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 633 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0142-2421
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✦ Synopsis
Abstract
Impedance and potentiodynamic polarization measurements show that the addition of nickel to superferritic 290 Mo alloys improves their resistance to the corrosion process in sulphuric acid and plays a disastrous part in hydrochloric acid. The chemical composition, thickness and depth profile of the passivating layers obtained in sulphuric acid are determined by using XPS and AES. In the anodic polarization domain, chromium oxide is the major component of the passivating layers and the addition of nickel increases its segregation slightly. In the cathodic polarization domain, the addition of nickel leads to passivating layers that are clearly more developed. Chromium oxide is no longer the major component, and an important segregation of molybdenum oxide and, to a lesser extent, nickel oxide towards the uppermost layer is observed.