Investigation of the Wetting Behavior of Cerium Dioxide Coatings
thesisposted on 01.07.2016 by Sin Pui Fu
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In this study, the wetting behavior of cerium dioxide will be studied. Cerium dioxide belongs to the group of rare earth oxides. Cerium dioxide has been studied widely because of its attractive properties such as high hardness, high thermal stability, high wear resistance, high chemical stability and good transparency. There are three main subjects that will be discussed in this dissertation. First, the intrinsic wetting behavior of cerium dioxide will be investigated. Second we will investigate methods for the development of robust, water repellent coatings. Third, the development of scalable techniques for coating of large structures will be presented. Cerium dioxide thin films were fabricated by pulsed laser deposition method. The effect of the oxygen pressure, substrate temperature, UV irradiation treatment and annealing treatment were investigated to understand the hydrophobicity of cerium dioxide. In addition, cerium dioxide nano-particles were synthesized by a hydrothermal method. Nano-flake structures create the surface texture that can result in superhydrophobicity after chemical modification to lower the surface energy. A novel superhydrophobic cerium dioxide nano-composite coating was developed using polyurethane and cerium dioxide nano-particles. Boiling tests, immersion in various acidic and basic solutions, peel tests and mechanical abrasion tests were performed to understand the long-term durability and stability of the superhydrophobic cerium dioxide nano-composite coating. Finally, the x-ray photoelectron spectroscopy results show that the oxide materials that we studied are intrinsically hydrophilic, but may become hydrophobic when the surface adsorbs hydrocarbon species in the ambient environment. However, cerium dioxide nano-particles can be used to fabricate superhydrophobic surfaces. The durability of the cerium dioxide composite coating can be improved by etching the aluminum alloy surface. Our novel cerium dioxide polymer composite coating has superior thermal stability, chemical stability and good adhesion.