Corrosion of thermally sprayed zinc and aluminium coatings in simulated splash and tidal zone conditions

Abstract

The corrosion rate in the splash and tidal zones of marine steel structures is very severe. Thermally sprayed coatings of zinc or aluminium and their alloys are among the most important technologies to eliminate this problem. This experimental study on the protective properties of thermally sprayed zinc and aluminium coatings on steel piles was conducted in an apparatus for simulating the marine corrosion environment. Particular attention was given to the anticorrosion performance of thermally sprayed zinc and aluminium coatings in the splash and tidal zones in combination with the cathodic protection of bare steel in the immersed zone. The experimental results showed that top to bottom thermal spraying of zinc or aluminium coatings on steel piles before their installation was effective, but that under cathodic protection conditions, protection of thermally sprayed zinc or aluminium coatings is effective up to the average middle tidal zone.