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Characterization of non‐Cr‐based deoxidizers on Al alloy 7475‐T7651
Author(s) -
Toh S.K.,
Hughes A.E.,
McCulloch D.G.,
duPlessis J.,
Stonham A.
Publication year - 2004
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.1938
Subject(s) - deoxidization , alloy , oxide , materials science , transmission electron microscopy , metallurgy , etching (microfabrication) , chemistry , scanning electron microscope , analytical chemistry (journal) , inorganic chemistry , layer (electronics) , composite material , nanotechnology , chromatography
The effects of three non‐chromate‐based deoxidizers, namely NaBrO 3 /HNO 3 , (NH 4 ) 4 Ce(SO 4 ) 4 /H 2 SO 4 and Fe(III)/HF/HNO 3 , on the Al alloy 7475‐T7651 were investigated. Several analytical methods were employed, including SEM, AES, transmission electron microscopy (TEM), electron energy‐loss spectroscopy (EELS) and glow discharge optical emission spectrometry (GDOES), to study the effects on the surface of this alloy after each treatment compared with the as‐received and alkaline‐cleaned alloy surfaces. The untreated alloy was found to have a thick oxide of 200–320 nm, consisting mainly of MgO. Alkaline cleaning results in an etching effect that thins the oxide and also deposits a thin silicate layer on the surface. In the case of the deoxidizers, there is significant removal of the native oxide of the alloy by the NaBrO 3 /HNO 3 deoxidizer. There is also evidence of intermetallic attack on the alloy. The (NH 4 ) 4 Ce(SO 4 ) 4 /H 2 SO 4 deoxidizer, which is a low‐etch‐rate deoxidizer, resulted in a slight thinning of the oxide. However, the effect was not significantly greater than with alkaline cleaning alone. The most effective deoxidizer in reducing the oxide thickness of the alloy is Fe(III)/HF/HNO 3 , in which the etch rate was sufficiently high to remove completely the native oxide. In this case, equilibrium between oxide removal and the formation of new oxides on the alloy surface was achieved. Copyright © 2004 John Wiley & Sons, Ltd.