Aluminum alloy 2024-T3 protection by magnesium-rich primer with chromate-free metal salts

The present findings support the significance of CO3 compounds in the protection of aluminum and its alloys by Mg-rich primers. It is proposed that the addition of Li2CO3 and Mg(NO3)2 to the primer facilitate the production of Mg(OH)2 and MgCO3 precipitates to improve protection. Anti-corrosion and anti-blistering effects were observed for formulations containing Li2CO3, Mg(NO3)2, and a low percentage of Mg metal particulates. The Mg(NO3)2 appears to reduce blistering while the Li2CO3 enhances defect protection. These effects are demonstrated throughout 1600 h of exposure to salt spray. Continued optimization presents the opportunity to design and implement unique cathodic protection plus corrosion inhibitor coating systems for use on aluminum substrates.