The evaluation of the corrosion resistance of metallic substrates protected by a hydrophobic coating

Abstract

With the advent of polymeric materials, various uses for these materials have been discovered in the quest to best utilize their unique characteristics. One property that a few polymers possess is hydrophobicity, that is water repelling. Consequently, one particular use for hydrophobic materials is in the area of corrosion protection. When applied as a coating material, hydrophobic polymers, theoretically, should provide excellent protection against corrosive environments. In order to ascertain the performance of hydrophobic materials in corrosion service, metallic substrates of aluminum, copper, and steel were coated with a hydrophobic coating termed conformal and subjected to a variety of intensive analytical examinations including Electrochemical Impedance Spectroscopy, realtime field studies, and scanning electron microscopy. To be able to gage the relative performance of the conformal coat, it is necessary to test similar uncoated metallic substrates as well as similar substrates treated with a nonhydrophobic corrosion preventative coat. This will allow direct comparisons to be made between the conformal coat and other commercially available coating products while allowing for an uncoated substrate to act as a baseline reference (i.e. a control). The results of these experiments showed that the performance of conformal as a preventative measure against corrosion were below expectations, especially in comparison to other commercially available non-hydrophobic coatings. This is most likely due to inadequate adhesion at the polymer-metallic substrate interface. Preliminary results show that improvements in the adhesive capabilities through the use of a base coating result in significant improvements in corrosion resistance.