Design with Magnesium
For general information on how to design with magnesium register for our Design Guide:
Is your seat too heavy?
Even primary structured seat parts can be successfully redesigned to pass 16G test
Surface protection for Elektron® 43
Elektron® 43, the optimised wrought version of the WE family of alloys, has inherently good general corrosion resistance (typically <30mpy). However, even though cabin interiors are not an extreme or overly aggressive environment, surface protection is required for improved performance and also to mitigate against galvanic corrosion.
The corrosion protection scheme suitable for aircraft cabin interiors includes:
- Pre-treatment: Chemical conversion coating or Plasma Electrolytic Oxidation (PEO).
- Top coat: Powder coating or Sealer (only PEO)
- Galvanic protection: Xylan (Polymer) coated washers or aluminium shims.
Due to current and anticipated environmental concerns, all treatments and solutions proposed are REACH compliant (Registration, Evaluation, Authorisation & restriction of Chemicals). Legislation restricted the use of hexavalent chromium chemicals in 2016.
The options have been deemed most appropriate:
- Chemetall – Ardrox 1769 (Gardobond X4729)
- Chemeon TCP-HF (was previously known as Metalast TCP-HF)
- Or Keronite (PEO coating)
In all case it is crucial that adequate cleaning is carried out to ensure that the top coat has sufficient adhesion and performance. Cleaning should include the following steps:
- Alkaline degreasing
- Rinsing (best practice is DI water)
- Acid etching
- Rinsing (again, best practice is DI water rinse)
From our evaluations, the best performance of the recommended conversion coating have been obtained when sufficient cleaning, using the steps detailed above has been carried out.
Cleaning helps with the corrosion protection and adhesion performance of the surface protection system. i.e. helps to avoid delamination and poor performance of the top coat.
Powder coatings proved to be suitable are hybrid epoxy/polyester. The ones we have selected are:
- Freilacke PB4001K
- IGP Duramix 331
Sulphuric anodising is often used on Aluminium. This does not work on Magnesium. Elektron have evaluated PEO (Plasma Electrolytic Oxidation) from Keronite. This is effective in corrosion protection, some additional work is however being carried out to determine the effect of the PEO coating on component fatigue performance.