Pulsed current hard anodizing procedures have been applied to the widely used heat treated aluminum alloys AA2024-T3, AA6082-T6 and AA7075-T6. The influence of frequency and of current amplitude on anodic oxide thickness, hardness, defectiveness, volumetric expansion ratio and on process faradic efficiency has been studied. Higher frequencies generate a decrease in coating electric resistance and in general they are less effective in order to overcome typical critical issues arising in alloys difficult to be anodized. In AA2024-T3 and AA6082-T6 higher frequencies led to slight increase in thickness, decrease in compactness and faradic efficiency while hardness remained almost constant or a bit higher. With higher frequencies in AA2024-T3 defective state significantly got worse, in AA6082-T6 it improved. In AA7075-T6 an almost frequency independent behavior occurred. The highest wave amplitude with a slightly cathodic “off” current (reverse pulse) allowed to obtain greater thickness, hardness and compactness while other current amplitudes did not show significant influence on properties analyzed; a very low, but still anodic, “off” current however induced slight hardness decreases.
|Data di pubblicazione:||2016|
|Titolo:||Pulsed current hard anodizing of heat treated aluminum alloys: Frequency and current amplitude influence|
|Autore/i:||Bononi, Massimiliano; Giovanardi, Roberto; Bozza, Andrea|
|Digital Object Identifier (DOI):||10.1016/j.surfcoat.2016.10.025|
|Codice identificativo ISI:||WOS:000390622200102|
|Codice identificativo Scopus:||2-s2.0-84991608286|
|Tipologia||Articolo su rivista|
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