The use of silane chemistries tailored to promote the adhesion of performance and appearance coatings to metal substrates are requiring new methodologies for measuring, approving, and implementing on commercial aircraft. Engineering performance, lean manufacturing, environmental and employee safety considerations are driving the commercial aerospace industry to replace long standing conversion coating materials and processes. Tailored silane chemistries such as Boegel are being considered for many of these applications. Silanes work by reacting with metal oxides providing a strong covalent bond, cross linking to form a tough barrier and have an organic functional group tailored to react with the specific resin system in the subsequent coating. Traditionally conversion coatings such as anodize and chromate conversion coating performance is validated based on meeting standalone requirements. Since tailored silanes are optimized to enhance adhesion, they rely on the subsequent coatings to provide corrosion protection; the overall performance is based on the entire coating system and not standalone characteristics. This is requiring the development and use of new methods that test that emulate the performance of the entire finishing system to evaluate the expected long term performance. Furthermore to build confidence that these new coating systems will perform as expected in service an incremental implementation approach is being adopted. This approach allows gathering in-service performance data that is used to validate and set limitations.

Presenter
Richard Wire, Boeing