ABSTRACT
Long-life and maintenance free anti-corrosion coatings are eagerly pursued, both by environmentalists as well as by those responsible for maintenance of steel structures. Traditional organic systems often do not meet these requirements. An obvious alternative is offered by using metal spray coatings: zinc for atmospheric applications, aluminium for sea water environment. For the latter, literature reports a service life exceeding 20 years. An extensive literature survey concluded the use of aluminium spray coatings for the protection of steel surfaces in marine applications to be Very promising’, nonetheless their actual use in The Netherlands is almost non existent. A possible explanation would be the poor documentation of practical experience in literature, combined with a lack of understanding of the protective mechanisms involved, resulting in little acceptance of aluminium coatings for corrosion protection. Therefore, commissioned by the Dutch Ministry of Transport, Public Works and Water Management, a series of laboratory experiments has been used to evaluate the protective properties of aluminium spray coatings on structural steel in sea water. Techniques included are cyclic polarisation, immersion exposure continuous and cyclic, current monitoring at artificial defects, tribological and mechanical testing toughness, flexibility and adhesion strength together with the influence of fouling organisms. It is concluded that aluminium based spray coatings appear to provide a suitable protection for steel structures in sea water.
