The characterisation and performance of Ce(dbp)3-inhibited epoxy coatings

Cerium dibutyl phosphate (Ce(dbp)3) was tested as a replacement for chromate corrosion inhibitors in a two-component epoxy applied to AA2024-T3 aluminium alloy. The interaction of the Ce(dbp)3 with the epoxy-amine functionalities were investigated using FTIR. Water uptake and Ce release were studied using weight gain and ICP-AES analyses, respectively. Corrosion resistance was assessed using filiform testing. It was found that the filiform corrosion resistance increased with increasing Ce(dbp)3 loading, and the best performance was obtained for the highest loading. The primer also showed improved wet adhesion. It was found using SEM and TEM that the corrosion protection offered by the Ce(dbp)3-inhibited epoxy and the improved wet adhesion were due to the development of an interfacial oxide at the metal/primer interface.