Self healing organic coatings on aluminium alloy

Aluminium and its alloys represent one of the most cost-effective production class of materials because of their high specific strength-to-weight ratio. However, they can be seriously limited by corrosion attack, especially in aqueous electrolytes containing chlorides, which leads to huge economic losses. Therefore, there is a strong demand for surface treatments or coatings to provide long-lasting anticorrosion performance. Several surface treatments or coatings have traditionally been adopted to improve the corrosion protection of metal alloys. Nowadays, the organic coatings are extensively used to impart corrosion resistance due to their good barrier characteristics, ability to include active anticorrosion pigments, like corrosion inhibitors, and low manufacturing costs. Nevertheless, these organic coatings show weak mechanical properties compared to the metallic substrate that imply to be damaged by mechanical impacts and lose their protective features. Hence, design and development of new organic coatings with autonomous self-healing properties have become an important target for many industries in the last years. This work presents a novel and simple route to produce poly(vinyl alcohol) (PVA) fibrous coatings, loaded with two different cerium (III) inhibitors (i.e., cerium nitrate and cerium acetylacetonate), by means of conventional electrospinning technique onto 6082 aluminium alloy for corrosion protection in 3 wt% NaCl solution. PVA has received many attentions due to its cheapness, good film forming ability, good chemical resistance, interesting mechanical properties and biocompatibility. In order to avoid PVA dissolution in aqueous environment, several cross-linking procedures were assessed. Collected mats were characterized by several analytical techniques. Electrochemical impedance spectroscopy (EIS) measurements showed that all the investigated coatings possess remarkable corrosion resistance. Self-healing effect has been observed only for artificially damaged coating loaded with cerium (III) acetylacetonate. Inductively coupled plasma mass spectrometry (ICP-MS) confirmed the release of cerium from broken fibers.