Stability and corrosion property of oil-infused hydrophobic silica nanoparticle coating

Hydrophobic SiO2 nanoparticles were sprayed onto the aluminium alloy substrate followed by the infusion of PFPE oil. Surface morphologies were observed by scanning electron microscopy and 3D laser confocal microscopy. The water contact angle and the polarization curve were measured before and after long-term immersion tests. The results showed that higher SiO2/PS proportion with lower content of polystyrene can enhance the water contact angle of the SiO2 nanoparticle coating. The water contact angle of the oil-infused surface is barely affected by corrosive immersion periods and the value keeps at a level of 110 degrees similar to 120 degrees. The oil-infused surface exhibits stable and superior corrosion resistance with the absence of obvious cathode and anode currents on polarization curves after corrosive immersion for 30d. In contrast, the negative shift of E-corr by about 300 mV and the increase of i(corr) by 3 orders of magnitude occur for the superhydrophobic coating.