For decades, the aerospace industry has been, and still is, relying on hexavalent chromium-based (Cr(VI)) compounds (chromates) as active corrosion inhibiting material for the corrosion protection of the structures. Unfortunately, these hexavalent chromium compounds are toxic and have been shown to be carcinogenic. Chromates are among the current chemicals for which industrial users must find substitutes or seek authorisation from EU regulatory authorities to continue to use them.
The ALMAGIC project, "Innovative Green Coatings of Aluminium and Magnesium Alloys", has focused on solving this problem by validating the innovative alternatives developed to chromium(VI) coatings for aluminium and magnesium alloys. ALMAGIC has ensured that the solutions developed comply with the REACH regulation, while meeting all the quality standards of the aerospace industry.
The ALMAGIC proposal has pursued the definition and development of new surface treatments without chromium (VI) in their composition to replace the coatings currently used in lightweight aerospace engine materials. Efforts have focused on obtaining the highest quality of coatings developed in accordance with the requirements of the aerospace industry. The AMS2473 quality standard has been used as a reference. In addition to the corrosive behaviour of free chromium coatings, their electrical and mechanical properties (fatigue), as well as their paintability, have been analysed.
Finally, ALMAGIC has included as an added value the performance of corrosion tests on paints through the performance of the following specific aerospace tests on painted specimens: NSST (according to ASTM B-117); QCT condensation test (according to ISO 6270); filiform corrosion test (according to EN 3665); and conical mandrel (according to ASTM D522). This gives ALMAGIC the advantage of validating the alternatives developed to Chromium(VI) treatments far beyond what is required by the call, and demonstrating the value of the solutions developed to be applied by the aerospace industry.
At the end of the ALMAGIC project it can be concluded that all the scientific and technical objectives set at the beginning of the project have been achieved. In addition, very promising chromium-free coatings have been found for each of the alloys studied.
