Abstract

We exercised iron-manganese phosphate composite coatings to defend the surface of D2 steel from corrosion. Addition of titanium
dioxide (additive) in different concentrations to the phosphating solution made significant difference in coating weight, coating
time, morphology, porosity, and anti-corrosion performance of phosphate chemical conversion coating on D2 steel was studied. The
resultant coatings were characterized by field emission scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray
diffraction measurements to ascertain the morphological features, chemical composition, and phase constituents, respectively.
The corrosion resistance of coated samples in 3.5% NaCl was evaluated by potentiodynamic polarization and electrochemical
impedance spectroscopy. Potential time measurement helped to track the phosphate coating formation and offer an indication about
completion of coating process. The results infer that the presence of additive could be formed highly corrosion resistant phosphate
composite coatings. It is an approach to determine the optimum concentration of additive which provides better protective layer.