Enhancement of the hydrophobic and anti-corrosion properties of a composite zeolite coating on Al6061 substrate by modification of silane matrix

Anti-corrosion properties of a silane–zeolite composite coating applied to aluminium substrates have been investigated. The composite film was prepared with different silane matrix formulations (varying bi-functional and tri-functional silane ratios). The results showed high hydrophobicity of the modified silane–zeolite coatings. Corrosion protection performance, during immersion in 3.5% NaCl solution, was evaluated by means of polarisation and electrochemical impedance spectroscopy tests. The polarisation curves evidenced a good corrosion resistance of all composite coating; though at high content of bi-functional silane, a reduction of corrosion protection performance was observed. At long immersion time (until 150 days), only the composite coating with low amount of bi-functional silane still evidenced good barrier properties.