Premium
X‐ray photoelectron study of oxides formed on Ni metal and Ni‐Cr alloy surfaces under electrochemical control at 25 °C and 150 °C
Author(s) -
Payne B. P.,
Keech P. G.,
McIntyre N. S.
Publication year - 2017
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6257
Subject(s) - nichrome , hydroxide , oxidizing agent , oxide , non blocking i/o , alloy , x ray photoelectron spectroscopy , nickel , metal , electrochemistry , metal hydroxide , nickel oxide , inorganic chemistry , materials science , layer (electronics) , chemistry , metallurgy , electrode , chemical engineering , catalysis , nanotechnology , organic chemistry , engineering
The oxide chemical composition on metallic Ni and NiCr alloy electrodes has been studied for changes in simulated reactor coolant solution chemistry, through a range of oxidizing potentials and pH settings at 25 °C and 150 °C. Even under strongly reducing conditions, the Ni surface has a 2‐nm layer of oxide and hydroxide from which further oxides form, depending on the subsequent oxidative step. For basic (normal operating) pH conditions and under oxidation potentials near 0 volts (vs. SCE), a predominantly Ni(OH) 2 layer is formed that appears to remain relatively stable up to at least 48 hours of oxidation at 150 °C. For the NiCr alloy, similar stability is imparted by a thin film of Cr(OH) 3 / Cr 2 O 3 and Ni(OH) 2 ./NiO. Under milder oxidizing (but still basic) conditions, the surface is stabilized by a thin film that is mostly Ni(OH) 2 /NiO. Under neutral solution conditions, the same oxide/ hydroxide films do not seem to be as effective in stabilizing the surface. Copyright © 2017 John Wiley & Sons, Ltd.