Hamid Hajji Abdul Poor - Department of Polymer Engineering and Color Technology Amirkabir University of Technology (Tehran Polytechnic) Tehran, Iran
M.M Attar - Department of Polymer Engineering and Color Technology Amirkabir University of Technology (Tehran olytechnic)Tehran, Iran
A Jalai Kandeloos - Department of Polymer Engineering and Color Technology Amirkabir University of Technology (Tehran olytechnic)Tehran, Iran

In this study, the cathodic disbondment of conversion coatings based on phosphate, titanium and zirconium compounds was investigated on mild steel. Four samples were prepared: Bare and phosphated steel, steel with titanium based conversion coating and steel with zirconium based conversion coating. Phosphated steel showed the highest resistance to disbondment whereas the zirconium and phosphate conversion coatings illustrate the lower amounts. Due to the fact that the rate of expansion of the disbondment area increases over time, it can be inferred that the cation diffusion is dominant. Regarding the cathodic disbondment mechanism, different alkaline condition is responsible to have different disbonding areas.

cathodic disbondment, conversion coatings, phosphate, titanium, zirconium, steel