The Morphologies and Wetting Properties of CK40 and AA2024 Surfaces Produced by Chemical Etching and Stearic Acid Modification

Abstract

By applying surface modification after chemical etching, superhydrophobic aluminum and steel surfaces were obtained. With different etching times, from all surfaces, different surface roughness values (Ra) were obtained. The effect of Ra’s on surface contact angles (CA) was determined by applying surface modification with stearic acid (STA) to all surfaces under the same conditions. With increased etching time, the surface roughness of both aluminum and steel has increased. Thus, in the current study, wettability seems to be affected only by the changes in surface roughness values. Although the etching reactive and the modification procedure are being same, higher contact angles were obtained on steel surfaces in shorter etching durations compared to aluminum surfaces. The maximum contact angles measured were 125.35 ± 8.32° on aluminum surfaces and 164.68 ± 3.62° on steel surfaces. With the current etching method, the minimum etching times required to reach the hydrophobic/superhydrophobic structure for the CK40 and the AA2024 samples were determined. Furthermore, optimum etching times under 10 min for CK40 and under 30 min for AA2024 were determined achieve the maximum contact angle.