Spray technology for more sustainable offshore wind towers

Translating a hot-dip concept into a thermal spray process creates some exciting scientific and engineering challenges

Beril Corlu

Spray technology for more sustainable offshore wind towers

Currently, thermal spray metallic coatings are used to protect offshore wind towers against corrosion – in combination with several topcoats for certain application fields. As the offshore market is seeking more durable products and ways to reduce the maintenance cost, the concept of a pre-coated steel plate emerged. Such a solution would not only reduce the manufacturing cost, but it would also allow the manufacturer to increase its capacity.

Zn, Al and Zn85/Al15 are the conventional references for thermal sprayed metallic coatings, and hot dip galvanised Magnelis® – with its well-known superior corrosion performance in chloride containing environments – is the high-end steel reference. We worked towards developing pre-coated plate concepts (process & product) for offshore wind towers, which could be extended to welded beams, sections from plates and LSAW pipes. For this purpose, arc spray and cold spray technologies for several coating compositions were screened at laboratory scale. The corrosion properties of these coatings were analysed by means of accelerated corrosion tests and interpreted by considering the coating composition, the microstructure and the corrosion products formed on the surface. Novel thermal spray alloy compositions could be produced, and very promising results – compared to the reference coatings – were obtained in terms of corrosion performance.