Say NO to Cancer: Chrome-Free Sacrificial Cermet Coatings in Aerospace

In the framework of European legislation (REACH regulations) requiring the elimination of hexavalent Chromium (Cr6+), which is carcinogenic, Castolin Eutectic - Monitor Coatings led the R&D project "Accelerated Manufacturing with Chrome Free Sacrificial Cermet Coatings in Aerospace" (AMSCA project) from June 2014 to May 2017. The project was successful and led to the development of a basecoat plus seal coat which met all functional requirements tested, showing that a solution could be deployed as a system and gaining significant levels of scientific understanding.

Existing sacrificial coatings, used for corrosion protection in aerospace, all contain Cr6+ and, therefore, must be replaced. Previous alternatives did not give acceptable performance, so new replacement materials were needed. A complete supply chain consortium, plus academic and CATAPULT support, has been brought together to address this issue. This project aimed to formulate a new sacrificial coating for corrosion protection of steel aero-engine components that is free from hexavalent chromium and demonstrate the technology to TRL5. In addition, improved, cost-effective application methodology was developed, incorporating automation where appropriate, to increase manufacturing rate and capacity along with reducing waste. The project partners included Rolls Royce, Indestructible Paint, Ashton & Moore, the Manufacturing Technology Centre, Granta Design, Loughborough University and Birmingham University.

In addition, Monitor Coatings, the Castolin Eutectic subsidiary in the UK, provided a comprehensive review and benchmarking activities and assisted in the down-selection of materials. As an established thermo-chemical coatings provider, Monitor Coatings assisted in process development by improving the processing methods and providing coated test pieces and trial components. In close collaboration with the MTC and Ashton & Moore, Monitor Coatings provided assistance in the scale up of the processing routes.Overall, the project was successful and worthwhile given that Cr-containing paint is used to protect nearly 1000 individual part numbers across Rolls-Royce. The coating formulated and developed for the project represents a significant step towards meeting current environmental requirements.

The socio-economic impact by non-authorisation of surface coating technologies containing chromium is estimated to total greater than US $6.7bn after 2024 REACH Sunset date. By far the largest contributor to that amount is the estimated 20,134 jobs that will be lost. These negative impacts are mitigated by the industrialisation of the hex chrome-free alternative technology developed during AMSCA project. There is a clear health and safety benefit for within the
Aerospace supply chain as the current technology may cause cancer. More so than authorisation, substitution would positively impact on workers that are now exposed to the chemical substance as well as the environment surrounding manufacturing facilities.

‘The project was worthwhile with clear economic benefits for Castolin Eutectic - Monitor Coatings. The new Cr free developments will guarantee that our products remain competitive, sustainable and be compliant with regulations for many years. These products will ultimately be incorporated into UK aero engines allowing our current market share to be maintained, mitigating the potential loss of revenue and competitive position posed by the REACH legislation, ’ explains Dr. Spyros Kamnis, Castolin Eutectic - Monitor Coatings Project Lead.