STRUCTURE AND COMPOSITION OF PASSIVE TITANIUM-OXIDE FILMS

The thickness and composition of several kinds of titanium oxide films formed on a titanium substrate were determined by surface analysis te chniques: X-ray photoelectron spectroscopy, Rutherford back scattering , X-ray diffraction and atomic force microscopy. Most titanium oxide s amples were prepared by anodisation, using a galvanostatic procedure. The films were shown to be composed of an amorphous TiO2 outer layer ( 10-20 nm thick) and an intermediate TiOx layer, in contact with the Ti O2 layer and the metallic substrate. The outer layer is sensitive to t he environment: its thickness usually decreases with ageing in a corro sive solution. A stabilisation procedure was proposed in order to impr ove its ability to withstand corrosion. (C) 1997 Elsevier Science S.A.