Double-layered surface decoration of flaky aluminum pigments with zinc aluminum phosphate and phytic acid–aluminum complexes for high-performance waterborne coatings

This paper reported the double-layered surface decoration for aluminum flakes by coating a zinc aluminum phosphate passive film, followed by fabricating a phytic acid–aluminum complex sealing film. The chemical compositions and structures of surface-decorated aluminum flakes were characterized by Fourier -transform infrared, X –ray photoelectron , and energy-dispersive X –ray spectroscopy and their morphology and double-layered structure were confirmed by scanning and transmission electron microscopy . The surface-decorated aluminum flakes not only show excellent dispersibility in water due to the enhanced hydrophilicity , but also exhibit good corrosion resistance and chemical stability against water. Most of all, the double-layered surface decoration leads to an improvement in optical performance of coating surface such as glossiness, flop index and distinctness of image compared to the single-layered one when the surface-decorated aluminum flakes are applied for waterborne coatings. The surface-decorated aluminum flakes developed by this work can well serve as a good flaky aluminum pigment for high-performance waterborne coatings.