Functionalized Polyhedral Oligosilsesquioxane (POSS) based coatings with multi level corrosion protections

Significant progress in recent years in replacing the chromates-based surface treatments (such as chromate oxide layer or chromic acid anodizing) has been achieved by new more environmental friendly substitutes. Unfortunately, they are still not as effective yet. The increasing needs for high-performance chromate-free coatings such as in the automotive, building and aerospace industries demand development of new systems with active corrosion protection. The present work aims at developing innovative multi-level protective “smart” coatings loaded with multi-functional additives with enhanced “self-healing” active protection properties, to improve long-term performance of metallic substrates. The purpose of this presentation is to introduce the European project CARBCOATPRO (http://www.sintef.no/projectweb/carbcoatpro/) and to present the initial results achieved in the project. The expected impacts are: 1) improved products with respect to current existing technologies with acceptable costs; 2) reduced usage of hazardous materials; and 3) sustainability of developed technology throughout the entire products life cycle. In the present work, modified hybrid functionalized polyhedral oligomeric silsesquioxane (POSS) were prepared via a two-step synthesis including a sol-gel process. Various additives were introduced in the modified POSS in order to achieve appropriate adhesion of the coatings on the substrates. The coatings from the obtained POSS mixtures were applied on aluminium substrates via a bar coater. Adhesion of the coatings was evaluated via a standard crosshatch test. Filiform corrosion test was preliminary performed on coated aluminium panels to assess the corrosion behaviour of the coatings. The results showed that homogeneous coatings were obtained with all compositions. Good adhesion of the coating with Al substrates was obtained with coatings containing functional groups that promote chemical bonding with the substrate. The coatings also showed promising protection against corrosion. These findings indicated that the POSS based coatings can be used as potential matrix for further additives to achieve smart stimuli responsive coatings with multi-level protection.