Nanocrystallized ceria-based coatings prepared by electrochemistry on TA6V titanium alloy

Abstract

Nanocrystallized ceria-based coatings were prepared on TA6V titanium alloy by using a three-step procedure: substrate pretreatment, electrochemical impregnation and final heat treatment. UV–vis and Raman in situ spectroscopies performed at the substrate interface during the electrochemical impregnation, showed experimentally for the first time that the interfacial deposit is made up of cerium hydroxide, incorporating also water molecules and nitrate ions coming from the electrolyte. Thermogravimetric analysis indicated also that the composition of the coating after the impregnation is given by the global formula CeO23.4H2O, while XRD analysis revealed that ceria with cubic fluorite crystalline structure is finally produced. Different preparation conditions were studied in view to control the nanosize of the supported ceria crystallites. It appeared that the final heat treatment is the most efficient operational parameter for the tuning of the particle size, that it can be thus well controlled from 5 to 30 nm between 300 and 700 8C.