The wettability of a solid surface is an important factor in the interaction of the surface with liquids. The wetting behaviour of a solid surface is a result of both its surface free energy and its morphology. Water wettability of solid surfaces is typically measured by their water contact angle. Low-wetting surfaces (hydrophobic) and extremely low-wetting surfaces (superhydrophobic) have various potential applications such as anti-icing coatings. In this paper, the wetting behaviour of atmospheric plasma sprayed (APS) titanium dioxide coatings and its dependence on the morphology of the coatings is investigated. The temperature and the velocity of the particles forming the coating are considered as the determining parameters for deposition conditions. By altering the two parameters, different surface morphologies were produced and their wetting behaviour was studied. The surface energy of the coatings was reduced using stearic acid treatment. It was found that within the range of particle velocity and temperature studied in this work, it is possible to produce surfaces with water contact angles close to a superhydrophobic state and as high as 144° as a combining result of both reduced surface energy and accomplished surface morphology. These high contact angle values were achieved through decreasing the temperature of the particles whilst increasing their velocity. Such coatings have a rough and irregular surface morphology which contributes to an increase in hydrophobicity of these coatings.
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