| Summary: | 碩士 === 國立臺北科技大學 === 機械工程系機電整合碩士班 === 107 === The combination of ultrasonic agitation and electroplating process can induce work hardening and improve the mass transfer of metal ions in the electroplating solution through the cavitation effect, thereby improving the mechanical properties and other chemical properties of the electroplated coating. The supercritical carbon dioxide assisted electroplating process can refine grain size and reduce the number and size of pores. As a result, the coating can be made more compact to reduce the surface roughness and increase the hardness of the film. However, so far only one study has discussed the combination of the above two technologies (supercritical carbon dioxide, ultrasonic agitation) applied in the electroplating process and analyzed its influence on the thin film. The experimental results show that ultrasonic agitation can effectively enhance the emulsifying effect and mass transfer of the electroplating solution. This study aims to use ultrasound (42 kHz) in supercritical Carbon dioxide (SC-CO2) electroplating process to investigate the effect of different electroplating processes on the properties of nickel films. From the results it was clear that higher ultrasonic irradiation resulted in higher grain refinement, higher hardness, better surface roughness and better corrosion resistance. The increase in hardness and surface flatness also enhanced the wear resistance characteristics of the metal film coating. Refined grains and smooth, flat surface have also significantly improved the corrosion resistance of the overall coating. When the parameters were set to obtain the deposit at pressure of 2000 psi and ultrasonic irradiation of 0.092 W/cm3, the grain size decreased from 77.91 nm to 8.87 nm, the hardness intensely increased from 284.9 Hv to 963.3 Hv, and the surface roughness decreased from 59.4 nm to 7.69 nm compared with conventional electroplating process. However, previous study has successfully combined advantages of ultrasonic agitation with SC-CO2 and applied this technique to electroplating of copper coating. This study will apply the method again to the metallic nickel thin film and verify that whether applied ultrasonic agitation to SC-CO2 electroplating process can effectively improve the mechanical properties of the thin film.
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