| Summary: | 博士 === 國立中興大學 === 材料工程學研究所 === 89 === The research purpose was to develop a new process and improve adhesion of diamond-like carbon films. In this study, an amorphous hydrogenated diamond-like carbon coating containing a small amount of titanium, and exhibiting high hardness, low friction coefficient, and superior adhesion strength, were successfully deposited onto M2 tool steel substrate using closed-field unbalanced magnetron sputtering (CFUBM) techniques. In DLC synthesized, an important role from changing the concentration of C2H2 can be controlled by a closed-loop optical emission monitor (OEM). The component, not only to regulate the reactive sputtering of metal and metal nitride/carbide interlayer, but also to control the amount of metal inclusion in the final DLC deposition. With the decrease of OEM settings, corresponding to a lower friction coefficient, longer wear life, higher microhardness and residual stress. The phase transformation from TiC to DLC is strongly influenced by OEM settings, and is demarcated on the OEM setting of 20%.
An interface layer of Ti/TiN and a transition layer of TiCxNy were incorporated to provide a supportive foundation for DLC and to solve the adhesion problem between DLC and steel substrates. These interfaces already improve the adhesion from 25 to 70 N between the DLC coating and the substrate. The total thickness of the DLC coatings can be controlled between 0.1 to 5 μm or higher. The DLC coatings showed excellent properties, i.e. high microhardness value (between 15 to 30 GPa or more), low friction coefficient against an WC and 52100 steel ball being in the range 0.07 to 0.2 in air, depended on the hardness of DLC coatings by OEM setting values.
The TGA analysis indicates the DLC films disintegrated at 350℃, showing typical graphitic transformation and oxidation behavior.
For ion implantation DLC coatings, the microhardness and the sp3/sp2 ratio evidently decreased from 16.2 to 11.6 GPa and 0.46 to 0.30, respectively, as ion energy increased. Results from damage by breaking some of the film’s sp3 bonds due to high-energy ion bombardment.
For the implantation of carbon in TiN coatings, the microhardness increases from 16.8 to 25.3 GPa, and new microcrystalline phases of TiCN and TiC are formed, depending on the implanted ion energy and dose. These newly formed microcrystalline phases can enhance the microhardness and reduce the wear of TiN films.
Final, this new model DLC process was successfully developed, including multi-interface and combined PVD/ PECVD process, using closed-field unbalanced magnetron sputtering technique.
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