Communication—Effect of Nano-Alumina Concentration on the Microstructure and Corrosion Resistance of Phosphate Chemical Conversion Coating

The effect of nano-alumina (Al2O3) concentration on the microstructure and corrosion resistance of phosphate chemical conversion (PCC) coating on 35CrMnSi steel was investigated by adding nano-Al2O3 into PCC bath. The results showed that the increasing nano-Al2O3 made the coatingmore compact and the crystals in the coating changed from plate-like to nodular shape. Electrochemical analysis revealed that the coating with finer nodular crystals prepared at the nano-Al2O3 concentration of 15 g/L presented the best corrosion resistance. (C) 2016 The Electrochemical Society. All rights reserved.