Polarized nickel-plating bath

Figure 9.15 illustrates the cathodic polarization curves of the composite nickel-plating bath containing different amounts of microcapsules. The addition of microcapsules enhances polarization and leads to the formation of tiny crystals in the composite coatings. 

Aramaki et al. [60] confirmed that ultrasonic waves modified cathodic polarization, so that a higher plating rate could be achieved for gold. Walker et al. [52] have found similar results for zinc plated out from a sodium zincate bath. The zinc plated out at a much faster rate in the presence of ultrasound (i.e. 1950 A m 2), when compared to the rate measured using a silent bath (250 A m-2). Similar effects have also been reported for many other metals including chromium [61] and silver [62] for nickel a 5- to 10-fold rate increase was observed [63]. 

---