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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. |
