Duplex Anti-Corrosion Protection of Steel Using a Combination of Hot-Dip Galvanising and Water-Soluble Paints

The goal of this paper is an evaluation of research aimed at corrosion and mechanical resistance of the so-called duplex system applied to a steel sheet. This system consists of a metal coating applied by hot-dip galvanising, to which an acrylic, water-soluble paint is commonly applied (commonly available on the Czech market) using standard technology in an air stream. For the purposes of the corrosion resistance comparison, one set of test specimens is provided only with a hot-dip galvanised coating. The mechanical resistance of applied anti-corrosion protection was determined by means of a pull-off adhesion test (according to the ČSN EN ISO 4624 standard), as well as an indentation test (according to the ČSN EN ISO 1520 standard). The corrosion resistance tests were then conducted in a salt spray environment (according to the ČSN EN ISO 9227 standard) for the samples not damaged by mechanical tests. Based on the obtained results, in general, waterborne paints with high dry matter content, low specific gravity and high zinc phosphate content, which are applied in several thinner layers, can be recommended.