The synergistic effects of additives on improving the electroplating of zinc under high current densities

In this work, the complicated interactions among NP16 (polyoxyethylene nonyl phenyl ether), OCBA (o-chloro benzyl aldehyde), and S40 (polyoxyethylene lauryl amine) are systematically investigated by means of linear sweep voltammetry for zinc deposition in a high current density (HCD) plating process from a weak acid zinc bath. NP16, an effective polarizer, depresses the formation of zinc dendrites in the HCD process. OCBA, strongly interacting with NP16 and S40, inhibits desorption of NP16 and S40 in the whole potential region of deposition. S40 acts as a depolarizer of zinc deposition, an inhibitor of hydrogen evolution, and a wetting agent in the HCD plating process when NP16, OCBA, and S40 are added simultaneously in the weak acid bath. The complicated interactions exhibit a synergistic effect on smoothening the deposit surface, refining the grain size, and promoting the current efficiency of zinc electroplating in a wide range of current density, successfully developing a Zn electroplating bath for the HCD plating process. The morphologies and crystalline structures of various Zn deposits are examined by means of scanning electron microscopy and X-ray diffraction respectively. The effects of the additives on the resultant crystal orientation and morphology are systematically discussed.