10157 Electrochemical Study of the Galvanic Interaction between the MG Rich Primer and its Al Substrate

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Product Number: 51300-10157-SG

ISBN: 10157 2010 CP

Author: Dante Battocchi, Maochen Yan, Dennis Tallman, Gordon Bierwagen, Nick Richter and Scott Hayes

Publication Date: 2010

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The cathodic properties of magnesium rich primers were investigated. An insulating layer was placed between the magnesium primer and aluminum alloy to create a barrier and separate the cathodic and sacrificial modes of protection. This was also done with a chromate rich primer. The open circuit potential (OCP) results show that the insulating layer stopped the cathodic protection of the substrate and only the sacrificial properties would be displayed. The non-insulated sample showed a mixed potential lower than the alloy between that of magnesium and the aluminum alloy. This indicates that there is cathodic protection of the metal substrate.[1] Electrochemical Impedance Spectroscopy (EIS) showed the insulated sample and the blank control to have similar properties. The non-insulated sample had lower impedance than the other samples because the metal pigments allowed for electrolyte penetration but had superior corrosion protection. The phase angle shows the insulated and blank controls to have the same mechanism while the non-insulated sample shows a different mechanism. The chromated samples, insulated and non-insulated, both had similar properties to each other which is expected due to the leaching of the chromates from the primer.