ZSM-5 coatings have been shown to be remarkably corrosion resistant in acids, bases and pitting-aggressive solutions [1-2]. Vanadium compounds are versatile corrosion inhibitors which are used to protect engineering materials. In ferritic stainless steels, V additions have been observed to increase the pitting potential measured in 3.5% NaCl solution [3]. In this study, we introduced vanadium into ZSM-5 coating synthesis and attempt to hence corrosion resistance and self-healing of as-synthesized V-ZSM-5 coatings. The coatings were characterized by XRD, SEM, EDX, polarization measurement, and shown to be highly corrosion resistant. The synthesis parameters (vanadium source, V/Si ratios, Na/Si ratios in the starting material) have been optimized in order to control the morphological characteristics and enhance their corrosion protection for aluminum alloys. Na/Si ratios were found to play a great role in the coating formation and their corrosion resistance. The V-ZSM coatings demonstrated good corrosion protection accompanied with released the vanadium. Under soaked in NaCl (0.856M) solution for some time (>12hrs), the scratched coatings showed much lower corrosion current than unscratched ones. The vanadium ZSM-5 films can potentially serve as an environmentally friendly, alternative corrosion-resistant coating for aluminum alloys.

Reference

[1] X. Cheng, Z. Wang, and Y. Yan, Electrochem. Solid-State Lett., 4, B23 (2001).

[2] A. Mitra, Z. Wang, T. Cao, H. Wang, L. Huang, and Y. Yan, J. Electrochem. Soc., 149 (10), B472 (2002).

[3] A. J. Sedricks, Corrosion of Stainless Steels (New York, NY: John Wiley & Sons), 118 (1996).