| Author: | Yeung, Ka Wai |
| Title: | Microwave processing of functional coatings based on nanocomposite materials |
| Advisors: | Tang, Chak-yin (ISE) Tsui, C. P. (ISE) Law, W. C. (ISE) |
| Degree: | Ph.D. |
| Year: | 2023 |
| Subject: | Nanocomposites (Materials) Coatings Microwaves Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Industrial and Systems Engineering |
| Pages: | xxi, 243 pages : color illustrations |
| Language: | English |
| Abstract: | The development of innovative microwave (MW) processing technology for synthesizing nanocomposite coatings with a controllable surface topography to produce functional coatings is the goal of this study. Nanocomposites have drawn considerable attention for tailoring material properties due to their enhanced properties compared to their bulk counterparts. It also allows unprecedented flexibility in tuning the coating properties with improved or pre-defined performance. In addition, surfaces with predesigned microarchitecture can also control the coating behavior and/or introduce additional functions. However, conventional technologies for the synthesis of coatings have limited control over the surface topography. Therefore, developing an innovative strategy for fabricating nanocomposite coatings with predesigned surface structures for advanced applications is necessary. This research is divided into two phases. First, an MW process is established for in situ syntheses of functional nanocomposites on various substrates. MW technology has several benefits over conventional methods for nanomaterial synthesis, including reduced activation energy, faster reaction rate, and higher product yield. However, the process is difficult to control when handling opaque and MW transparent materials and coating systems having constituent materials with dissimilar dielectric properties, so, a susceptor-assisted MW process (SMP) is developed. Three model functional coating systems, silicon dioxide (SiO2)/titanium dioxide (TiO2) coatings, TiO2/calcium phosphate (TiO2/CaP) coatings, and pyrolytic carbon-supported multiwalled carbon nanotubes (MWCNTs/PyC) coatings have been produced. The functional coatings prepared for satisfying surface protection, bioactivation, and electrochemical requirements were tested and analyzed. In the second phase of the research, direct laser writing (DLW) was introduced to construct conductive coatings with predesigned surface microarchitectures using photocurable resins as the precursor material. An innovative MW processing technology was developed by combining the SMP and DLW. CNTs and copper-containing organometallic monomers were used to modify the photocurable resins to promote MW absorption and improve the electrical and electrochemical properties of the PyC-based coatings. Followed by the SMP, PyC/CNTs and Cu/PyC nanocomposite metamaterial coating surfaces were successfully produced. The results discovered the potential of the proposed hybrid technology for producing high-performance functional coatings for electrochemical sensors and energy storage devices. This study established an innovative MW processing technology for advanced functional coatings based on nanocomposite materials. The SMP was developed for synthesizing coatings with desired functions by investigating suitable material compositions, coating procedures, and MW processing conditions. The coating quality and performance were evaluated systematically. The SMP process not only overcomes the difficulties of processing nanocomposite coating systems with MW technology but also provides an effective means for in situ syntheses of nanocomposite coatings with enhanced performance. The hybrid processing technology based on the SMP and DLW was successfully developed to generate PyC-based nanocomposite metamaterial coating surfaces. This research provides a better understanding of the critical factors for fabricating advanced functional coatings, such as the precursors' composition and the processing conditions. Such knowledge can enhance technological advancements in producing novel, high-performance devices. Further investigation of the precursor material selection, the design, and the realization of advanced sensors and energy storage devices through the proposed technology are recommended for future work. |
| Rights: | All rights reserved |
| Access: | open access |
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