description
- "Magnesium alloy castings are used in the fabrication of helicopter gearbox components because the advantages in terms of specific weight / mechanical properties and suitability for the casting process. However, improvements in helicopter performance by the use of magnesium have been offset by corrosion problems. More corrosion resistant alloys and improved protective finishing systems are needed. Besides, these systems must conform to environmental regulations and the use of hazardous substances. Both chemical and electrochemical methods are used for the modification of magnesium surfaces. Despite the many ways to form chromate free chemical conversion layers on the surface of Mg alloys, there are also significant gaps for real implementation and commercial significance of these developments and their use in specific applications such as the protection of cast Mg alloys used in helicopters. TECNALIA and PROMET consortium partners own proprietary formulations for the surface treatment of non-ferrous alloys with already demonstrated properties for the protection of Mg alloys. In the case of TECNALIA, the starting point will be an own patented process for conversion coating of Mg alloys based on phosphates and permanganates chemistry. In the case of PROMET several proprietary formulations based respectively on CrIII, cerium and manganese chemistries will constitute the starting point. A selenious acid self-healing process for brush-application will be also tested. This project aims to readjust and optimize these baseline treatments to extend their application to the helicopter transmission MgWE43 and EV31A Mg casting alloys as required by the addressed topic, fulfilling all the demanded requirements by the aerospace industry."