Obtaining ZrO2 + CeO x + TiO2/Ti compositions by plasma-electrolytic oxidation of titanium and investigating their properties

Abstract

Regularities of the effect produced by Ce2(SO4)3 salt introduced in an aqueous electrolyte containing Zr(SO4)2 on the plasma-electrolytic formation of oxide coatings on titanium, their composition, and structure are studied. ZrO2 + CeO x + TiO2 three-phase oxide coatings with a thickness about 10 μm are obtained. The coatings involve ZrO2 cubic phase. The ZrO2-to-TiO2 phase ratio in the coatings can be controlled. The zirconium content in the coatings reaches 20 at %, while that of cerium is 3–5 at %. The surface layer (∼3-nm thick) contains Ce3+ (∼30%) and Ce4+ (∼70%). Pores in the surface part of coatings have diameters around or smaller than 1 μm and are regularly arranged. The obtained systems have a certain catalytic activity with respect to the oxidation of CO to CO2 at temperatures above 400–450°C. The coatings are corrosion-resistant in chloride-containing environments. The thickness h of coatings depending on the charge Q supplied to the cell is described by the equation h = h 0(Q/Q 0) n , where n = 0.35 and h 0 is the thickness of the coating formed at Q 0 = 1 C/cm2.