Pulse Electrolysis for the Production of Hard Ni/TiO<sub>2</sub>-ZrO<sub>2</sub> Composite Coatings

Abstract

The electrolytic codeposition has drawn interest as an alternative method for the preparation of metal matrix composite electrocoatings with improved properties. Moreover, the application of a current periodically varied by time during electrodeposition, i.e. pulse current (p.c.), instead of the commonly used direct current (d.c.), has been proved to lead to the preparation of surfaces with well-defined properties. In this work, Ni/TiO2-ZrO2 composite electrocoatings were produced under direct and pulse current conditions. The synergetic action of both the pulse application and the simultaneous codeposition of the two different types of particles on the structure, the morphological characteristics and the microhardness of the composite electrocoatings, were studied. Concerning their mechanical behaviour, it was found that the Ni/TiO2-ZrO2 deposits prepared by pulse electrolysis are characterized by Vickers microhardness threefold harder than the d.c. ones.