Alternatives to hexavalent-chromium-based aluminum surface treatment
PhD student Shoshan Abrahami and her supervisors associate professor Arjan Mol and professor Herman Terryn from the Department of Materials Science and Engineering published surprising results this month in Nature’s partner journal Material Degradation. They have developed, together with Fokker Aerostructures and the Technical University of Denmark, alternatives for hexavalent chromium-based aluminium surface treatment for bonding in aircraft construction.
As a result of the health risks associated with the use of hexavalent chromium (Cr6+) in the surface treatment to prevent the corrosion of aluminium, scientists are working hard to find alternatives. Until now it has proven difficult to find alternatives that provide comparably effective protection, particularly when it comes to applications in harsh corrosive environments. The research team, which includes Arjan Mol, Herman Terryn and Shoshan Abrahami, have now discovered that an alternative adhesive mechanism involves a complex interaction between the roughness of the surface (morphological features) and the oxide used (surface chemistry). This takes us a step closer to finding alternatives for Cr6+-based surface treatment, including for adhesive bonding in aircraft construction.
image above: The production of metal-to-metal bonding at Fokker Aerostructures
[Translate to English:] (a) surface pre-treatment (panels hanging above the anodizing bath), (b) parts drying on the rack after pre-treatment, (c) primer application, (d) adhesive application, (e) a bonded part)
Consult the publication for more information
Interface Strength and Degradation of Adhesively Bonded Porous Aluminum Oxides, npj Materials Degradation, DOI: 10.1038/s41529-017-0007-0, http://rdcu.be/u9S8 (open access)
Authors: Shoshan Abrahami, Arjan Mol (TU Delft), Herman Terryn (Vrije Universiteit Brussel/TU Delft), John de Kok (Fokker Aerostructures), Visweswara Gudla and Rajan Ambat (Technical University of Denmark)
Contact Arjan Mol, Research Group Corrosion Technology and Electrochemistry, TU Delft, J.M.C.Mol@tudelft.nl