Enhancing corrosion protection

Aircraft platforms are often required to remain in service for three or four decades, and this puts a premium on the work of DMTC and its partners to counter a range of causes of damage and deterioration including corrosion, structural fatigue and foreign object damage.

A particular challenge related to the ADF’s in-service helicopter fleets is the utilisation of magnesium alloys in the production of gearboxes and associated housings. While there are some advantages in terms of tensile strength, density and vibration damping performance, poor corrosion resistance is a significant limitation on the use of magnesium alloys in defence equipment platforms.

Corrosion, when discovered, can be sufficiently severe to render components as ‘beyond economic repair’, and replacing gearbox components requires extensive offline maintenance work and disassembly of the entire gearbox structure. As such, any improvements that can be made to the corrosion resistance of the component – in terms of enhancing its material structure – will translate into extension of service life and reductions in the maintenance cost and burden to Defence. More recently developed magnesium alloys are reportedly more corrosion-resistant but are not yet widely utilised.

To address these challenges, the DMTC collaboration involving DST and UQ is developing a deeper understanding of the corrosion behaviour of legacy and emerging magnesium alloys. Importantly the DMTC project is also evaluating the performance of existing and developing improved coatings for application as protective barriers on these magnesium components. The project is seeking to remediate a range of corrosion-related issues not covered by other DMTC maritime or air platform projects.

The project will involve detailed testing, including field trials, of the potential suitability and effectiveness of a range of corrosion-inhibiting treatments and schemes. The expected outcome is a significantly-improved scientific understanding which will enable designers, manufacturers and maintainers alike to modify their practices in order to achieve improved corrosion performance.