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XPS Study of non‐rinse chromate treatments
Author(s) -
Yoshikawa Yukihiro,
Watts John F.
Publication year - 1993
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.740200509
Subject(s) - chromate conversion coating , x ray photoelectron spectroscopy , coating , substrate (aquarium) , metal , chemical engineering , chemical composition , chemistry , conversion coating , materials science , inorganic chemistry , metallurgy , nanotechnology , organic chemistry , oceanography , geology , engineering
The formation of a non‐rinse chromate coating on various metal substrates—iron, zinc and Zn–13% Ni—Has been studied by XPS. The coating contains both organic and inorganic species from the treatment bath and varies in composition depending on the amount of reducing agent added to the bath to provide the mixed Cr 3+ /Cr 6+ stoichoimetry. The outer surface of the coating is rich in Cr 3+ and there is evidence of a chemical reaction between the treatment solution and the metal substrate. An ultrahigh vacuum (UHV) taper sectioning stage has been used in conjunction with small‐area XPS to probe the interfacial chemistry between the coating and the substrate. The enhancement of Cr 3+ at this interface is observed at a higher level than at the outer coating surface. These observations are interpreted on the basis of the reaction mechanism proposed for chromate coating formation.