T.G. Harvey

Cerium-based conversion coatings on aluminium alloys: a process review

Abstract Rare earths are among the most promising options for replacing chromate conversion coatings on aluminium. In nearly three decades of research, several hundred papers have been published in the area, the bulk of which has never been reviewed. This paper reviews the literature on rare earth coating processes, with particular emphasis on those based on cerium. It is concluded that several process areas are poorly understood, some of which are critical to further progress in the field. These include the development of industrially suitable pretreatments, technologies for coating non-aerospace alloys and seals to enhance corrosion performance and paint adhesion.

Interaction of Ce(dbp)3 with surface of aluminium alloy 2024-T3 using macroscopic models of intermetallic phases

Abstract The mechanism of corrosion inhibition by cerium(III) dibutylphosphate [Ce(dbp)3] on aluminium alloy 2024-T3 (AA2024-T3) has been investigated using macroscopic models of the intermetallic (IM) phases in the alloy. Polished specimens of pure Al (99·999%) and the macroscopic IM phases Al2CuMg, Al7Cu2Fe and Al3Fe were each coupled to a large surface area of AA2024-T3 to simulate the interaction they experience in the alloy. Samples were immersed in 0·1M NaCl with 200 ppm Ce(dbp)3 for 24 h, and the resulting surfaces characterised by scanning electron microscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy and Raman spectroscopy. Ce(dbp)3 was found to interact differently with each of the different phases examined, providing evidence for a multifunctional corrosion inhibition mechanism.