Chromate Inhibition of Filiform Corrosion on Organic Coated AA2024-T3 Studied Using the Scanning Kelvin Probe

2004 ◽  
Vol 151 (7) ◽  
pp. B406 ◽  
Author(s):  
H. N. McMurray ◽  
G. Williams ◽  
S. O’Driscoll
Keyword(s):  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Filiform Corrosion

Scanning Kelvin Probe Studies of Cosmetic (Filiform) Corrosion on AA6016

2006 ◽  
pp. 679-686
Author(s):  
H.N. McMurray ◽  
A.J. Coleman ◽  
G. Williams ◽  
Andreas Afseth ◽  
G.M. Scamans
Keyword(s):  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Filiform Corrosion

Time-lapse potentiometric imaging of active filiform corrosion using a scanning Kelvin probe technique

PhysChemComm ◽  
2001 ◽  
Vol 4 (6) ◽  
pp. 26 ◽  
Author(s):  
G. Williams ◽  
H. N. McMurray ◽  
D. Hayman ◽  
P. C. Morgan
Keyword(s):  
Time Lapse ◽  
Kelvin Probe ◽  
Probe Technique ◽  
Scanning Kelvin Probe ◽  
Filiform Corrosion

Scanning Kelvin Probe Studies of Filiform Corrosion on Automotive Aluminum Alloy AA6016

2007 ◽  
Vol 154 (7) ◽  
pp. C339 ◽  
Author(s):  
H. N. McMurray ◽  
A. J. Coleman ◽  
G. Williams ◽  
A. Afseth ◽  
G. M. Scamans
Keyword(s):  
Aluminum Alloy ◽  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Filiform Corrosion

Scanning Kelvin Probe Studies of Cosmetic (Filiform) Corrosion on AA6016

2006 ◽  
Vol 519-521 ◽  
pp. 679-686 ◽  
Author(s):  
H.N. McMurray ◽  
A.J. Coleman ◽  
G. Williams ◽  
Andreas Afseth ◽  
Geoff M. Scamans
Keyword(s):  
Heat Treatment ◽  
Surface Layer ◽  
Polyvinyl Butyral ◽  
Open Circuit ◽  
Grain Structure ◽  
Metal Loss ◽  
Kelvin Probe ◽  
Fine Grain ◽  
Scanning Kelvin Probe ◽  
Filiform Corrosion

Scanning Kelvin Probe (SKP) potentiometry is used to systematically investigate the effect of surface abrasion and subsequent heat-treatment on the open-circuit potential in humid air of the AA6016 surface. SKP is also used to follow the kinetics of filiform corrosion and to determine characteristic potentials associated with the electrolyte-filled filiform head and dry filiform tail. It is shown that simply abrading with 180 grit SiC produces a surface potential up to 0.5V lower than the bulk. When the abraded sample is overcoated with a 30 micron layer of PVB (polyvinyl butyral) and exposed to HCl a fast, superficial filiform corrosion (FFC) is observed in which metal loss is limited to the thickness of the surface layer. Filiform head OCP values are similar to that of the surface layer, whereas filiform tail OCP values are similar to the bulk. A mechanism is proposed in which the ultra-fine grain structure of the surface layer produces an anodic activation and the potential difference between the surface layer and the bulk provides and increased thermodynamic driving force for corrosion. For post-abrasion heat treatment temperatures up to 350°C the fast filiform process is followed by a slower, deeper form of FFC.

Delamination of Poylmer Coatings from Metal Substrates: Submicroscopic and Molecular Aspects

2002 ◽  
Vol 734 ◽  
Author(s):  
M. Rohwerder ◽  
E. Hornung ◽  
Xing-Wen Yu
Keyword(s):  
Suitable Model ◽  
Kelvin Probe ◽  
Scanning Kelvin Probe ◽  
Mesoscopic Structure ◽  
Investigation Methods ◽  
Filiform Corrosion ◽  
First Results ◽  
Cathodic Delamination ◽  
Reaction Zones ◽  
Molecular Aspects

Delamination of organic coatings from metal surfaces can occur in a number of different ways, e.g. as pure cathodic delamination, as Filiform corrosion or a mixture of these. In fact, in most technical systems the pure cases are the exception and, of course, delamination is usually very slow. It has been shown that in fast delaminating systems the length scales may range between several 100 μm and several millimetres, while in systems which show slow delamination the reaction zones can be confined to submicroscopic distances [1]. This underlines the importance of investigation methods with submicroscopic resolution. As a very promising new technique Scanning Kelvin Probe Force Microscopy (SKPFM) was applied for the investigation of cathodic delamination and filiform corrosion on a submicroscopic scale [1, 2]. Indeed, these first investigations have shown that SKPFM gives basically the same information as the standard Scanning Kelvin Probe (SKP), but with a much improved resolution. It could be shown, for instance, that the extension of the reaction zone seems to be much narrower than would have to be assumed from the SKP measurements. Based on the knowledge about the different delamination types that was obtained from investigations with the standard SKP [3–12] the SKPFM should be the ideal tool to get information on the submicroscopic scale. However, SKPFM alone is not sufficient for revealing the underlying fundamental mechanisms; of even higher importance is the knowledge of the molecular and mesoscopic structure at the buried interface. In this paper a design for suitable model samples is proposed and first results are presented.

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