Organic Inhibitors for Aircraft Coatings

摘要

Although an organic coating by itself provides corrosion protection by forming a physical barrier between the metallic substrate and the environment, it is the corrosion inhibitor which plays the most important role in corrosion prevention scheme of any coating system. Hence, any long-term application of these materials requires the presence of active inhibitors. Currently, the most effective inhibitors are forms of chromates which are incorporated into both the surface treatment and primers. Chromium is a known carcinogen and must therefore be eliminated. The main objective of this study is to investigate a multi-prong approach to address the replacement of chromates by environmentally friendly inhibitors in the current surface treatment and primer scheme, known as the permanent foundation layer. The main focus is directed towards organic inhibitors, which can be introduced into the primer as fixed/mobile entities. A number of organic compounds including, amines, phosphonates, imidazole and thiols were tested to investigate their corrosion prevention properties. Scanning vibrating probe, anodic polarization and immersion data indicate effective inhibition provided by a number of laboratories developed formulations. Detailed surface analysis was conducted to investigate the role of newly developed inhibitor in forming a complex with corrosion active metal sites leading to an effective corrosion prevention.