Corrosion protection of Zn-phosphate containing water borne dispersion coatings on steel: Part 1: Design and analysis of model water based latex films on iron substrates

Model thin film coated substrates were developed to investigate the functionality of Zn-phosphates, the polymeric binder and emulsifiers during the interface formation on iron substrates. By means of grazing incidence FTIR-spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy, it was observed that ultra-thin films of zinc phosphates and hydroxides, with a thickness of less than 2 nm, adsorb on the iron surface during the formation of the latex coating/metal interface. Moreover, film formation conditions were developed for the deposition of hexagonal closed packed defect-free-monolayers of latex particles over large areas. This allowed the application of time of flight SIMS for the analysis of the monolayer-metal interface and the study of its morphology before and after film annealing. After annealing, the monolayer film showed an enrichment of surfactants at the particle boundaries and at the interface to the phosphate and hydroxide covered metal substrate.