| Summary: | 碩士 === 大同大學 === 機械工程學系(所) === 98 === Residual stress is often observed during a thin film deposition process. The stress not only influences the work life of the component but it also affects the microstructure and mechanical properties. This thesis investigates how the internal stress affects the mechanical properties and biocompatibility. The residual stress is carried out by etching the silicon substrate material by 30wt% KOH with different time. Four different rough surfaces were made and diamond like carbon films were deposited on these rough surfaces afterwards. Optical microscopy, surface profiler, atomic force microscopy, Raman spectra, XPS, sessile drops and cell counter were utilized to examine the surface morphology, roughness, internal stress, ID/IG, hydrogen content, wettability and cell viability. For mechanical properties, the nanoindentation was used to measure the hardness and elastic modulus.
The results show the roughness in the substrate is increased with more etching time, but after DLC deposition, the roughness is reduced. As the roughness increases, the internal stress, ID/IG and sp2/sp3 increases. The rougher surface also leads to more hydrophobic nature and is adverse for cell culture. The biocompatibility of DLC in different rough surface is characterized by ECV30 cell for 48 and 72 hour cell cultures. For rough surface, the cell number for 48 or 72 hour cell culture is less than that in smooth surface. The more hydrophobic nature or less surface energy might be the reason. This study shows that for DLC deposited on a rough surface, the induced internal stress will change the surface and mechanical properties and is harmful for cell culture.
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