Multifunctional hybrid sol-gel coatings for Marine Renewable Energy Applications: Synthesis, Characterization and Comparative Analysis with Organically Modified Silicon Precursor Coatings

Hybrid coatings for cavitation erosion protection of aluminum alloys, have been developed, based on a sol-gel process and applied by the dip coating technique. This work aims to investigate established hybrid sol-gel coatings synthesized using organically modified silicon precursor 3-methacryloxypropyltrimethoxysilane (MAPTMS) mixed with zirconium (IV) propoxide. In the present research, the established baseline coatings were modified by adding different concentrations (1%, 1.5% and 2%) of cross-linkable hexamethylenediisocyanate (HMDI) diluted in 60% ethanol. The influences of the amount of crosslinker incorporated into the coatings on abrasion, corrosion and cavitation erosion protection were studied. The hydrophobic nature, thermal and electrochemical properties of the coatings were evaluated using Water Contact Angle (WCA), Differential Scanning Calorimetry (DSC), Open Circuit Potential (OCP) and Potentiodynamic polarization (PDS) techniques. Furthermore, cavitation erosion and abrasion tests were completed on all coatings and rankings of these were produced based on mass loss measurements and derived mean depth of erosion.