The role of surface morphology in the barrier properties of epoxy coatings in different corrosion environments

Hydrophobic epoxy coatings with particulated surfaces were prepared via soft lithography using different abrasive papers as the templates. With the increasing surface roughness, the hydrophobicity of these surfaces first increased and then decreased and a maximum water contact angle of ∼136° was obtained by using a P2000 abrasive paper as the template. Electrochemical impedance spectroscopy (EIS) was used to study the role of surface morphology in the coatings’ barrier properties under wet–dry cyclic immersion and in salt-spray environments. The results demonstrated that the hydrophobicity induced by the trapped air in the surface microstructures produced stronger-barrier properties than that produced by a smooth coating when exposed to wet–dry cyclic immersion. The strongest barrier performance was achieved by the coating templated with the P2000 abrasive paper. However, these microstructured hydrophobic coatings deteriorated faster in the salt-spray tests because of the direct deposition of salt electrolyte particles on the coating surfaces and the increased coating surface area. Under the salt spray condition, the coating obtained from P6000 abrasive paper exhibited the fastest deterioration.