The formation of polypyrrole film on zinc-coated AZ91D alloy under constant current characterized by Raman spectroscopy

The electropolymerization of conducting polypyrrole (PPy) film on zinc-coated AZ91D magnesium alloy under constant current control in aqueous sodium tartrate containing pyrrole monomer was investigated using Raman spectroscopy and surface observation. Zinc oxide and zinc hydroxide are initially formed, which are then replaced by a zinc tartrate salt layer. The PPy nucleation is initiated on the zinc layer covered by zinc tartrate, followed by three-dimensional growth of the PPy layer.

► The detail of formation of PPy was analyzed.
► The coating consisted of the ZnO, Zn-tartrate, and the outer PPy layer.
► The PPy nucleation is started on Zn-tartrate covering zinc.