The surface of flake zinc powder was modified by a silane coupling agent KH570 , and the surface of flake aluminum powder was modified by the single and composite coatings of tetraethyl orthosilicate ( TEOS) , vinyl-triisopropoxysilane ( VIPOS ) and acrylic acid ( AA ) . Chromium-free Dacromet coatings were prepared with the modified zinc powder and aluminum powder as the basic components. The potentiodynamic polarization curves of the modified zinc-aluminum coatings in 3. 5％ NaCl solution were measured. The surface of the TEOS/VIPOS mod-ified aluminum powder coating was smooth, with no obvious particles. The dispersion and stability of the coating were good. Compared with the unmodified zinc-aluminum coating, the corrosion rate of the TEOS/VIPOS and TEOS/VIPOS/AA modified aluminum powder coatings decreased significantly. The TEOS/VIPOS modified alumi-num powder coating had a smaller corrosion current density (1. 01μA/cm2) and corrosion rate (0. 011 mm/a). After soaking in 20％ ammonium nitrate solution for 2 h, the surface of TEOS/VIPOS modified aluminum powder coating was smooth and the corrosion resistance was good.
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