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Structure and Properties of Polymer-Derived SiBCN Ceramics
| Title: | Structure and Properties of Polymer-Derived SiBCN Ceramics. |
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| Name(s): |
Chen, Yaohan, Author An, Linan, Committee Chair Fang, Jiyu, Committee CoChair Xu, Chengying, Committee Member Zhai, Lei, Committee Member Huo, Qun, Committee Member Gong, Xun, Committee Member University of Central Florida, Degree Grantor |
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| Type of Resource: | text | |
| Date Issued: | 2012 | |
| Publisher: | University of Central Florida | |
| Language(s): | English | |
| Abstract/Description: | Polymer-derived ceramics (PDCs) are a unique class of multifunctional materials synthesized by thermal decomposition of polymeric precursors. Due to their unique and excellent properties and flexible manufacturing capability, PDC is a promising technology to prepare ceramic fibers, coatings, composites and micro-sensors for high-temperature applications. However, the structure-property relationships of PDCs have not been well understood. The lack of such understandings drastically limited the further developments and applications of the materials.In this dissertation, the structure and properties of amorphous polymer-derived silicon carbonitride (SiCN) and silicoboron carbonitride (SiBCN) have been studied. The SiCN was obtained using commercially available polysilazane as pre-ceramic precursor, and the SiBCN ceramics with varied Si-to-B ratio were obtained from polyborosilazanes, which were synthesized by the hydroboration and dehydrocoupling reaction of borane and polysilazane. The structural evolution of polymer-derived SiCN and SiBCN ceramics from polymer to ceramics was investigated by NMR, FTIR, Raman, EPR, TG/DTA, and XRD. The results show a phase-separation of amorphous matrix and a graphitization of (")free(") carbon phase, and suggest that the boron doping has a great influence on the structural evolution. The electric and dielectric properties of the SiCN and SiBCNs were studied by I-V curves, LCR Meter, and network analyzer. A new electronic conduction mechanism and structure model has been proposed to account for the relationships between the observed properties and microstructure of the materials. Furthermore, the SiBCN ceramics showed the improved dielectric properties at characterization temperature up to 1300 (&)#186;C, which allows the fabrication of ultrahigh-temperature wireless microsensors for extreme environments. | |
| Identifier: | CFE0004195 (IID), ucf:49014 (fedora) | |
| Note(s): |
2012-05-01 Ph.D. Engineering and Computer Science, Mechanical, Materials and Aerospace Engineering Doctoral This record was generated from author submitted information. |
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| Subject(s): | polymer-derived ceramics -- polymer synthesis -- amorphous ceramics -- structure characterization -- SiBCN -- electrical properties -- dielectric properties -- sensor | |
| Persistent Link to This Record: | http://purl.flvc.org/ucf/fd/CFE0004195 | |
| Restrictions on Access: | public 2012-05-15 | |
| Host Institution: | UCF |
