Smart containers can be produced with polyelectrolyte multilayers that can release inhibitors in response to environmental changes at the coating defects. In this study, mesoporous TiO 2 hollow spheres were adopted as carriers for the encapsulation of corrosion inhibitor. The inhibitor-loaded TiO 2 containers were modified by polyelectrolyte shells using layer-by-layer self-assembly technology. The release behaviour of the encapsulated inhibitor was investigated using UV-visible spectroscopy. Corrosion protection performance of the epoxy coating with polyelectrolyte-modified TiO 2 containers was studied using electrochemical impedance spectroscopy and scanning Kelvin probe (SKP) techniques. Epoxy coating with the polyelectrolyte-modified TiO 2 containers provided better barrier properties than that of the blank coating. Waterborne epoxy coating impregnated with the polyelectrolyte-modified TiO 2 containers presented a significant self-healing effect after immersion in 0.5 M NaCl solution from the SKP results.

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In this work, the corrosion behavior of high-strength low alloy (HSLA) steel welded joints in natural seawater solution was investigated by electrochemical and immersion tests. The experimental results prove that the corrosion resistance of the weld metal (WM) was higher than that of the base metal (BM). The scanning Kelvin probe results show that the potential distribution of the BM zone is lower than the heat-affected zone (HAZ) and WM zone. The scanning vibrating electrode technique results demonstrate that the initial attack for the HSLA welded joint majorly took place in the BM zone after immersion in natural seawater. The corrosion morphology of the HSLA welded joint after immersion was observed by scanning electron microscope. The corrosion morphology of BM and HAZ regions tends to be uniform corrosion, whereas it is mainly pitting corrosion for the WM zone.

Available chlorine is known to play a significant role in metal corrosion due to its oxidising properties. In this paper, the effect of available chlorine concentration on corrosion behaviour of the low alloy marine steel was investigated by electrochemical and immersion tests. Experimental results show that the corrosion rate of low alloy marine steel is accelerated with the increase of available chlorine concentration in seawater. The localised electrochemical dissolution of the steel is more active with the concentration of available chlorine increasing. Energy dispersive spectroscopy (EDS) was performed to understand the composition of the corrosion products that the large enrichment of Cl element occurred for the high available chlorine concentration (100 ppm) after 720 h exposure to seawater. The influence of available chlorine concentration on mechanical property of low alloy marine steel indicatesthe less impact on the tensile and yield strength of the low alloy marine steel.