Zn-ZrO2 nanocomposite coatings obtained by electrodeposition

In the present work Zn-ZrO2 nanocomposite coatings (ZrO2 0.2-2.5 wt%) on mild steel substrate have been produced by electrodeposition technique with high current efficiency. Electrodepositions were performed at 35°C by using a chloride bath containing gelatine and yttria-stabilized zirconia nanoparticles (<100 nm); the tests were carried out under galvanostatic control with pulsed direct current, using a cathodic square wave (pulse frequency 1 Hz, duty cycle 50%). The coatings were characterized by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and Vickers microhardness measurement. Corrosion potential and polarization resistance measurements were performed in 3.5 % NaCl solution. The composite coatings showed an improvement in hardness and in corrosion resistance with respect to the pure zinc coatings.