Passive and transpassive films formed on a nickel alloy in ammoniacal solution |
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| Authors: | E Asselin A Alfantazi S Rogak |
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| Institution: | 1. Department of Materials Engineering The University of British Columbia 6350 Stores Road, Vancouver, Canada V6T 1Z4;2. Department of Mechanical Engineering The University of British Columbia 2054‐6250 Applied Science Lane, Vancouver, BC, Canada V6T 1Z4 |
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| Abstract: | The surface of alloy 625 (Ni‐22Cr‐9Mo) was characterized with XPS and AES depth profiling after exposure to mildly alkaline ammoniacal solution at open circuit and after potentiostatic treatments at various potentials. It was determined that the passive surface film was a Cr and Mo oxide that was depleted in Ni with respect to the bulk alloy. Increased solution temperatures or oxygen concentrations decreased the Ni to Cr ratio in the passive film. The alloy's transpassive film was characterized using SEM and EDX as well as XPS. The transpassive film was heavily depleted in Ni and Cr and consisted mainly of an oxide of Fe. Copyright © 2009 John Wiley & Sons, Ltd. |
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| Keywords: | passive film Ni alloys XPS alloy 625 AES ammonia |
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