NICKEL BASE ALLOYS - THEIR ELECTROCHEMICAL REACTION AND FORMATION OF SURFACE FILMS IN SOLUTIONS REPRESENTING GEOLOGICAL WATERS
The present report deals with the studies on the passivation and depassivation processes of nickel base alloys in different geological waters. The depassivation in sulfuric acid solution shows that the films formed are relatively thin, especially for films formed in salt brine, and exhibit also three layers which were observed previously by Glow Discharge Spectrometry (GDS). In chloride rich solutions, like salt brine and 3 % NaCl solution, the pit nucleation potentials E-np depend on several physicochemical parameters such as the temperature, the chloride concentration and the inhibiting species concentrations and the alloy compositions. For the last parameter, the beneficial actions of the alloying elements, Mo and Cr, are pointed out.The surface analysis by SDL and SIMS, which show an accumulation of Mo at the film - matrix interface and inside the pit, are in good agreement with the hypothesis of the redeposition of dissolved Mo, on the matrix inside the pit.
Bibliographic Reference: EUR 9669 FR (1985) MF, 50 P., BFR 150, BLOW-UP COPY BFR 250, EUROFFICE, LUXEMBOURG, POB 1003
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Record Number: 1989123052100 / Last updated on: 1987-01-01
Available languages: fr