Parameter optimization of nanosilver colloid prepared by electrical spark discharge method using Ziegler-Nichols method

Abstract

This study adopted a self-developed real-time monitoring micro electrical discharge machine (micro-EDM) system for nanosilver colloid preparation through the electrical spark discharge method (ESDM). The developed system relies on the parameters modulated through a closed-loop proportional-integral-derivative (PID) controller and optimized through the Ziegler–Nichols method to get modulated PID parameters, affect the process duration of ESDM. In the present study, samples were prepared under varying process durations and pulse modulation (TON–TOFF) duty cycles. Various instruments were applied to compare the absorbance values, discharge success rates, and particle size distributions of these samples. The results indicated that, compared with the samples prepared through the closed-loop PID controller, the samples prepared through the modulated PID parameters exhibited substantially higher absorbance, discharge success rates, and smaller particle size distribution. The improved discharge success rate is increased to an average of 129% compared to the original parameters. The particle size distributions of samples based on the empirical data averaged 10–20 nm, whereas the samples based on the parameters modulated through the Ziegler–Nichols method were primarily smaller than 10 nm, with the averaged size being 7.068 nm. These confirmed the effectiveness of the Ziegler–Nichols method in optimizing ESDM nanosilver colloid preparation.