Effects of Temperature on Corrosion Resistance of NanoZirconia-Based Conversion Coating

Document Type : Research Article

Authors
Ali Payami Golhinl 1
Reza Eslami-Farsani 1
Morteza Amrooni Hossaini 2
Hamid Khorsand 3
1 Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran
2 Supplying Automotive Parts Company (SAPCO), Karaj, Iran
3 Supplying Automotive Parts Company (SAPCO), Karaj,Uran
/2015.3.12.3
Abstract
In this study the influence of temperature on the formation of a zirconium-based conversion coating is investivated for the automotive industry. The coated samples were obtained by dipping galvanized steel substrates in a hexafluorozirconic acid based solution. The coating was characterized using scanning electron microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The protective efficiency of coatings was evaluated by potentiodynamic polarization measurement and salt spray test. The SEM EDS and AFM analyses revealed that treated galvanized surfaces are covered with nano nodules. According to polarization measurements and salt spray tests all samples treated with the conversion solution had a better corrosion performance in comparison with the blank galvanized sample. From the potentiodynamic polarization experiment, the best anti-corrosion performance occurred when the temperature of solution was considered 25 c.
Keywords
Conversion coating
Nanoceramic
Atomic force microscopy
polarization
Salt spray .test