Metal-containing, hydrogenated carbon films (Me-a-C:H) is a special class of nanocomposite films of particular interest since they can be multifunctional through the synergistic interaction of their individual components. Thus, nanocomposite thin films possess high potential in a wide field of engineering applications, especially in small scale devices. A series of multifunctional nanocomposite Co-a-C:H thin films have been synthesized by a hybrid chemical vapor deposition (CVD) and physical vapor deposition (PVD) process to uncover the relationship between synthesis, microstructure and properties. The effects of deposition parameters on the microstructural evolution and properties have been systematically studied.
The results showed that the microstructure can be controlled through proper adjustment of the processing parameters, to produce Co in the shape of: nano particles, elongated particles, wormlike columns, self-assembled multilayers, self-assembled nano columns embedded in an amorphous a-C:H matrix. Self-assembly of Co nano columns in a-C:H is discovered. As-deposited Co-a-C:H thin films are composed of defect rich ε-Co encapsulated in a-C:H matrix. Regarding the properties, raising C content (reducing Co content) in the films improves their hardness and corrosion resistance and decreases friction and wear rate. All the Co-a-C:H films exhibit a low surface roughness. Nano columnar Co-a-C:H films show size-dependent magnetic behavior, such as superparamagnetic and perpendicular magnetism. Annealing studies reveal that the phase transitions of Co in Co-a-C:H film follow the sequence of Co-a-C:H film → (300 °C) ε-Co + δ ′Co2C → (343 °C) hcp-Co + δ ′Co2C → (407 °C) hcp-Co + graphite → (459 °C) fcc-Co + graphite. A mechanism and a zone diagram are presented to describe the microstructural evolution of Co-a-C:H films. Knowledge gained from this research allows the design and synthesis of nanocomposite Co-a-C:H films and other multifunctional systems of interest for new applications in the field of nanotechnology.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11122004-093614 |
| Date | 12 November 2004 |
| Creators | Wang, Fengli |
| Contributors | Gary R. Byerly, Efstathios I. Meletis, Elizabeth J. Podlaha-Murphy, Tryfon T. Charalampopoulos, Philip W. Adams |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11122004-093614/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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