| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系 === 107 === This study employed a self-developed micro-electrical discharge machining (Micro-EDM) system as the primary axis to prepare a nano-silver colloid through the electrical spark discharge method and provide a periodic direct-current pulse power source between the positive and negative electrodes. An arc discharge (arc) was generated using an electric field, producing high temperature and high heat and thereby melting the surface metal of the silver electrode to manufacture silver nanoparticles. This research aimed to identify and determine all discharge conditions of the Micro-EDM system. The discharge conditions can be categorized into three states: gap discharge, short circuit, and open circuit. The short-circuit phenomenon may not only affect the life of the system but also consume the electrode, resulting in the generation of large non-nano silver particles. Therefore, this study designed a new logic judgment circuit to identify the short-circuit rate and subsequently determine the optimal proportional–integral–derivative (PID) method from various PID closed-loop control methods to reduce the short-circuit rate of the system. The presence of silver nanoparticles was verified using ultraviolet-visible spectroscopy (UV-Vis), and a Zetasizer nano-system (Zetasizer) was used to analyze the particle size, zeta potential, and UV-Vis absorbance. Finally, analysis of silver nanoparticle properties was performed using transmission electron microscopy. The research results suggest that the reduction in short-circuit rate not only considerably improved process efficiency but also validated the optimized nano-silver colloid.
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