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 1,000 individual part numbers across Rolls-Royce. The coating formulated and developed for the project represents a significant step towards meeting current environmental requirements.