The marine environment is considered to be a highly aggressive environment for metal materials. Steels are the most common materials being used for shipbuilding. Corrosion is a major cause of structural deterioration in marine and offshore structures. Corrosion of carbon steel in marine environment becomes serious due to the highly corrosive nature of seawater with high salinity and microorganism. To protect metallic materials particularly steel against corrosion occurrence various organic and inorganic coatings are used. The most used are the polymeric protective coatings. The nanostructured TiO2 polymer coating is able to offer higher protection to steel against corrosion, and performed relatively better than other polymer coatings.

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This research work presents the results obtained from a comparative corrosion evaluation of welded joints on uncoated steel in flat position, welded joints in flat position on steel protected with polymeric film, and welded joints in flat position on steel covered with nanocomposite polymeric film (primer reinforced with TiO2 nanoparticles). The electrochemical methods of open circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy were used for corrosion evaluation. The results of the electrochemical tests indicate that titanium oxide reinforcing polymeric film to form nanocomposite layers over naval welded steel increases the corrosion protection of polymeric film as compared with unmodified primer.

The life time of the metallic materials exposed to marine environment is influenced by their corrosion resistance. The marine environment is considered to be very aggressive to metallic materials used in the marine industry. In order to protect metallic substrates against corrosion process, important efforts have been made to develop corrosion resistance coatings, besides the cathodic protection systems. Thus, during the last years there were developed a series of organic protective coatings that have as principal component one or more polymers. This paper present a comparative investigation regarding the corrosion resistance of: i) uncoated naval steel EN32, ii) coated naval steel EN32 with a two-component polymeric primer and iii) coated naval steel EN32 with two-component polymeric primer followed by epoxy polyurethane paint coating. All the samples have been subjected to corrosion in seawater collected from the Black Sea (Mangalia sea port). In situ electrochemical measurements as: open circuit potential (OCP), polarization resistance (Rp), potentiodynamic polarization (PD) and cyclic voltammetry polarization (CV) were performed to monitor the corrosion process. The results showed an improved corrosion resistance of polymeric coatings in marine environment compared with uncoated naval steel EN32