Abstract
The objective of the subject is to prepare superhydrophobic coatings nanostructured hybrid organic-inorganic compounds on the surfaces of metals,mainly on copper and aluminum for their ecological protection against environmental corrosion. The technique of electrochemical deposition and is used to modify metal surfaces to achieve superhydrophobic properties. The coating solution chosen is stearic acid.
The reaction between copper and stearic acid will be happened in the application of DC voltage, whereas aluminum stearate is difficult to be found on the aluminum surface which may due to the dissolve of ethanol. The surface coating on the aluminum therefore can be done in two steps. Firstly, aluminum surface is electrochemically deposited in the C11SO4 solution to get copper coating surface.
Subsequently, the copper-aluminum samples will be coated in the galvanic mode to obtain superhydrophobic sample surface. Preliminary results on the preparation of superhydrophobic coatings on the surfaces of copper have been made where the copper pieces were immersed in stearic acid solution by applying an electric field simultaneously. Studies of wetting coatings are being evaluated using contact angle goniometer. The characteristics of the coating are being evaluated using scanning electron microscope (SEM) and X-ray diffraction (XRD) methods. Corrosion resistance of all coatings will be tested by immersing the samples in the corrosive solution. The dynamic behavior of corrosion will be evaluated using the SEM, XRD and by studies of wettability.
In the investigation of superhydrophobic coating on the copper substrate, in the case of 30V DC voltage, the contact angle improves with the increase of reaction time.Besides, the contact angle is getting larger with higher voltage. On the other hand,superhydrophobicity of aluminum coating surface is achieved when coating time is exceeded 5min. In the study of corrosion tests of copper, the contact angle decreased with the coating time of 24h. However, the surface still proposes superhydrophobicity.The results show that the surface with superphobic coating has better corrosion resistance than that without coating. In the corrosion test of Copper/Aluminum, the contact angle decreases as the corrosion time increases. However, the superhydrophobicity of coating surface on aluminum is lost when corrosion time exceeds 3h.
Key Words: coating; superhydrophobicity; corrosion; aluminum
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