COCA : Understanding the mechanisms of interphase formation in anodized aluminium/paint systems

The COCA (COuche Colmaté Anodisé / Anodized Sealing Coat) project was initiated in 2020 by IRT M2P and Safran Aircraft Engine (SAE) in collaboration with a consortium of companies and research laboratories, including Safran Tech, Airbus Helicopter, and the IPREM Institute. The COCA project is led by Laëtitia Thomas, R&D Project Manager in the IRT M2P institute. The aim of the first thesis was to understand the sealing mechanism of aluminum anodic oxide in the presence of silicon in the sealing bath on Aluminum 2618. Céline Mira began her thesis in 2021 at IPREM under the direction of Jean-Charles Dupin and defended it in May 2024.

Safran Landing Systems (SLS), using the same surface treatment as SAE, initiated a second thesis under the co-direction of Maëlenn Aufray (CIRIMAT laboratory), a specialist in adhesion, epoxy coatings, and interphase formation, and Jean-Charles Dupin (IPREM laboratory), a specialist in XPS and surface characterization. SLS was joined by AkzoNobel (paint formulator), GIT (applicator), CIRIMAT, and IPREM, the host laboratories of the second thesis student. The research, undertaken by Maxime Blanc, aims to understand the interaction between anticorrosive epoxy primer and anodized and sealed aluminum. To address this problem, the work has been divided into three main areas.

1) The first focuses on the independent characterization of the epoxy primer using differential scanning calorimetry (DSC), IR and RAMAN spectroscopy, and the substrate surface using XPS, GD-OES, and microscopy.;
2) The second area centers on the interaction between the primer and the substrate, studying the interface and interphase in both dry and wet conditions using XPS, DSC, X-ray tomography, and the 3-point bending test (ISO 14679);
3) The final area aims to understand the influence of surface treatment and coating application parameters on the durability of adhesion in dry conditions, with the goal of adjusting SLS parameters for 2214 and 7050 aluminum alloys.

Last update : June 2025