Superhydrophobic and lubricant-infused porous surfaces are two classes of non-wetting surfaces that are inspired by the adaptation of natural surfaces such as lotus leaves, pond skater legs, butterfly wings, and Nepenthes pitcher plant. This dissertation focuses on fabrication and in depth study of bioinspired functional metallic surfaces for applications such as power plant condensers and marine applications. Toward that, first, facile and scalable methods are developed for the fabrication of superhydrophobic surfaces (SHS) and lubricant-infused surfaces (LIS).
Second, the corrosion inhibition mechanism of SHS was systematically studied and modeled via electrochemical methods to elucidate the role of superhydrophobicity and other parameters on corrosion inhibition. The anti-corrosion properties of SHS and LIS were systematically studied over a range of temperatures (23°C–90°C) to simulate an actual condenser environment. Moreover, the environment of application often involves using harsh cleaning chemicals. The fabricated non-wetting surfaces were examined over a wide range of acidity and basicity (pH=1 to pH=14). Third, the durability of SHS and LIS is systematically assessed using a set of testing protocols including water impingement tests, scratch wear tests, and accelerated chemical corrosion tests. Considering that industrial environments of application are often turbulent, in addition to static long term corrosion tests, long term dynamic durability was studied in a simulated turbulent condition. Fourth, the performance of the fabricated nonwetting surfaces was systematically studied against calcium sulfate scaling in turbulent conditions and different temperatures. An analytical relationship based on the Hill-Langmuir model is proposed for the prediction of fouling on nonwetting and conventional surfaces alike in dynamic conditions.
Overall 1048 individual samples were studied via over 3000 measurements in this dissertation to establish a comprehensive fundamental knowledge base on fabrication and anti fouling characteristics of metallic nonwetting surfaces, which profoundly helps to design appropriate surfaces and fabrication methods based on the use environment. / Doctor of Philosophy / Metallic surfaces such as copper, brass, and aluminum are everywhere in our daily lives. From tumblers, household pipes to the bank of tubes in power plants condensers. Fouling of these surfaces has significant performance and economic impact. Scaling is a type of crystallization fouling like the familiar limescale everyone is familiar to see around the surface of a house kettle. Corrosion is another type of fouling and is detrimental to metallic surfaces. For example, 50% of water consumption in the U.S. is being used in thermo-electric power plants where fouling of metallic surfaces will impede the flow of working fluid, therefore increasing power needed for pumping, decrease efficiency, and decrease ultimate lifetime. One study in 2019 shows corrosion costs 3% of the gross national products of China and it is already known to be similar for other major economies like the USA, which is a hefty cost.
Nature has inspired a lot of solutions for mankind. In this work, inspired by natural surfaces such as lotus leaves, butterfly wings, and pond skater legs, a class of superhydrophobic surfaces (SHS) was fabricated. Moreover, a closer look at how the complex human body puts everything in order exposes one of its most striking and essential characteristics: how wet and lubricated its interfaces are. Our lungs, eyes, joints, intestine, bones; either hairy or porous, all are lined wet surfaces that work as fouling inhibitors and defect free surfaces. This also have been observed elsewhere such as on Nepenthes pitcher plant. Inspired by these, another class of non-wetting surfaces, lubricant-infused surfaces (LIS) was fabricated. This dissertation for the first time investigates a rational methodology in the fabrication of metallic SHS and LIS and their anti-scaling and anti-corrosion properties in different environments of application, including a range of temperature (23°Câ€"90°C), various solutions (pH=1 to pH=14), and long-term static and dynamic (turbulent condition) durability. It is believed that this work would profoundly help to identify appropriate nonwetting metallic surfaces based on the intended use environment.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/106787 |
| Date | 30 November 2021 |
| Creators | Mousavi, Seyed Mohammad Ali |
| Contributors | Mechanical Engineering, Pitchumani, Ranga, Mahajan, Roop L., Morris, Amanda, Ellis, Michael W. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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