REACH Compliant Hexavalent Chrome Replacement for Corrosion Protection

Metal corrosion and wear currently costs industry $1.5-2 trillion globally per annum. The basis of many systems to mitigate these problems utilise compounds containing hexavalent chromium (Cr6+) as used in: chromic acid anodising (CAA); chemical conversion coatings; primers; paint, and hard chrome plating (EHC). Corrosion and wear are of particular importance to the aerospace industry where protection requirements are extremely severe. European REACH legislation is expected to ban the use of Cr6+ containing materials by 2016 due to its carcinogenic properties. This is a critical issue for
the aerospace industry and has been highlighted as a priority in the 2011 National Aerospace Technology Strategy. A number of attempts have been made to introduce Cr6+ free materials and processes. The solutions have been found not to be as robust as expected, due in part, to the lack of validated, accelerated testing methods, resulting in unexpected failures. Individual aerospace companies are developing their own, proprietary solutions. This has caused problems in the supply chain, which it is finding difficult to support. This bid addresses this situation by bringing together an integrated aerospace based team from SMEs to academia to identify innovative solutions and develop robust accelerated testing methods that accurately reproduce severe environmental applications. This will enable the sector to adopt a common approach to the development and testing of REACH compliant protection systems including new processes. The technical approach to address this problem has been defined by the consortium including industrial, supply chain and academic
partners. The approach has 6 key objectives: (1) Benchmark existing corrosion, wear and adhesion testing methods modifying these to better represent service conditions; (2) Based on the knowledge developed in (1) ,develop new test where gaps are identified; (3) Test Cr6+ based solutions through the tests specified in (1) and (2) to establish a baseline and test potential Cr6+ free solutions through the same matrix to establish deviation from the baseline; (4) Where the alternate solution is better than current the product will be characterised in terms of its chemistry and microstructure to
provide a scientific explanation for its performance. The consortium would then quantify the variation of the production system to evolve a product that consistently meets the protection requirements; (5) Where the alternate solution performs
badly a root cause analysis by the universities will be carried out to determine the weaknesses and identify the improvements necessary to create a viable alternate. This knowledge will be fed back to the material supplier and applicator to enable them to formulate new protection and application systems that address the identified weaknesses, and; (6) New CAA and EHC replacement processes will be developed to mitigate the risk of failure of the industrially-selected solutions. In terms of benefits, the consortium OEM's and first tier companies will specify the new coatings for use on their
products. Those who have their own processing facilities will also set up the capability to produce the new coatings. The specialist processing companies will be able to set up facilities to provide these coatings and to provide the materials these process will require. Additionally, new areas of academic research will be opened up, thus strengthening the science base. A succesful project will result in the removal of Cr6+ surface coatings from the operating environment. This will address the
environmental concerns and reduce operating costs. The materials testing protocols will lead to reductions in materials testing costs and shorter time to market for future coatings. The consortium will investigate the possibility of incorporating the outputs into standards. Where appropriate, the outputs will be protected and suitable IP arrangements will be part of the consortium agreement.

This project is capable of delivering impact as it brings together a team including academia, SMEs and OEMs in the aerospace sector, in a fully integrated, structured, science-based, systems approach to the development of testing methods and materials processes in an area that has traditionally been developed on an empirical basis.

This has not been attempted before in this area and will result in innovative test methods, materials and processes being developed and a significant up skilling of the sector.

This approach will capture this knowledge in a useable form for the future and makes it widely available outside of the aerospace sector. In terms of measurable impact, the main beneficiaries from the proposed study will initially be the consortium OEM's and first tier companies that are within the aerospace sector. As best practice in terms of testing is disseminated and more widely adopted, then other industries will benefit from the standardised and reliable corrosion and wear test methodologies generated from this research. Such materials testing protocols will lead to reductions in materials testing costs and shorter times-to-market for future coatings. The validation of Cr6+ free coatings will impact upon both the aerospace and, also eventually, other key industrial sectors such as automotive and defence that also require similar processes. Key benefits to the aerospace sector will be the specification of new coatings for use on their products. Those who have their own processing facilities will be able to set up the capability to produce the new coatings. The specialist processing companies, including SMEs, will be able to set up facilities to provide these coatings and to provide the
materials these process will require. A successful project will result in the removal of Cr6+ surface coatings from the operating environment which will address the environmental concerns and reduce operating costs.

This research will work towards the aim of the elimination of Cr6+ by 2016, as currently proposed under REACH. The proposed project represents an opportunity for the UK aerospace industry to become leaders in the area of Cr6+ replacement through the development and demonstration of an innovative common testing programme and materials and processing. This research will be underpinned by a science-based understanding at leading universities and a centralised materials data management architecture. This research will also lead to the potential for development of alternative Cr6+
processes in the partner universities by understanding the failure mechanisms of existing candidates.