The wettability of solid surface is a critical property, which is controlled by the chemical structure and geometric microstructure of the surface. The super-hydrophobic surface with water contact angle (WCA) greater than 150° has been attracted much attention due to practical benefits in daily life as well as industrial applications, for example, in snow adhesion, formation of protective layers, oxidative stress and electricity conduction. Various fabrication methods such as chemical etching, surface treatment, and functional film deposition have been used to improve hydrophobic properties. Conventionally, two-step process has been widely used to develop super-hydrophobic surfaces as follows: first, the rough nano- and micro-patterns are introduced onto the surface, and then, an organic coating with low surface energy is applied to smooth the rough surfaces. In the two-step process of surface morphology variation, Al or alloy metal plate or sheet were used to test a super-hydrophobic surface via chemical etching using mixed solutions, such as Cu(NO3)2:HNO3 and silane, HNO3:H2O2 and stericacid:N,N-dicyclohexylcarbodiimide, NaOH and fluorinated silane, NaOH and ethanol.
In this study, we optimized the surface modification using two-step chemical process to enhance hydrophobic properties of Al film deposited by RF-magnetron sputtering system. RF-magnetron sputtering technique is effective method for optimizing the hydrophobicity formed on various Al film thicknesses because it has many advantages such as easy-control, low-temperature process, uniform surface, and suitable for the growth of nanostructured films. Vacuum-deposited metal film on various glass substrate can be widely and simply used to address issues such as corrosion protection, cleaning, friction and abrasion compared to metal sheet or plate. We expect that our surface modification process will enable the fabrication of super-hydrophobic surfaces across large areas. In order to a super-hydrophobic surface, we conducted a two-step surface modification of Al-coated glass substrate by potassium hydroxide (KOH) etching and lauric acid coating. In this work, in order to super-hydrophobic surface, we used the lauric acid that has been studied with a self-cleaning property after the oil contamination or a novel eutectic mixtures for hydrophobic low viscosity because of their hydrophobic properties of large contact angle and small sliding angle as well as eco-friendly property.