CHROMIC ACID FREE ANODIZING PROCESS FOR AIRCRAFT ALUMINUM ALLOYS

CHROMIC ACID FREE ANODIZING PROCESS FOR AIRCRAFT ALUMINUM ALLOYS

For several decades, chromic acid anodization (CAA) has been typically used for the protection of critical structures with all kinds of joints in aircraft and automobile industries, specifically to provide corrosion resistance and adhesion with primer layers. However, use of chromic acid in CAA process generates high environmental risk which highly discourages its usage for various applications. As per NASF forecast, chromate free coating systems are likely to be in place by 2026 for aerospace industry. For the past one decade Boeing has been using anodization process along with dilute chromate solution sealing as an alternate to CAA for aircraft application. Similarly, Airbus uses anodization process along with sealing in either boiling water or hexavalent chromium based solution. However, till date use of hexavalent free chromium coating process has not yet been explored in the total anodizing process. Thus, finding a suitable alternate is a mandate specifically to phase out hazardous chromate based coating with equivalent or superior performance. At SED, CSIR-NAL, a modified chromate, phosphate and fluoride free eco-friendly anodization process has been developed to improve the corrosion resistance of aluminium and its alloys in corrosive environment. The process is energy efficient compared to conventional CAA. The TRL of this technology is 5 to 6 and the certification of this process is in progress.

 

Outdoor Exposure study (for 6 months) at Coastal area- Mandapam Camp


Last updated on : 18-12-2017 09:51:33am