Some Observations on the Surfaces of Titanium and Practical Titanium Alloys by ESCA

Abstract

Various kinds of treatment such as ion-etching, filling with diamond, dipping into mixed acid (HF:HNO₃=1:3), anodic oxidation and dry-oxidation in air were used for the surface preparation of pure titanium, Ti-0.16%Pd, Ti-5%Ta, Ti-15%Mo-0.2%Pd and Ti-8%Mn alloys, and characterization of their surfaces was investigated by ESCA. The results obtained were as follows:
(1) The ESCA spectrum of Ti2p_3⁄2 obtained from pure titanium which was filed with diamond consisted of four components TiO₂, Ti₂O₃, TiO and metallic Ti, and the higher oxidation states predominated on the outer surface of the oxide film. ESCA data also showed that the alloying elements were present in different valent states such as oxide, suboxide and metal, of which fractions depended on the way of surface treatment.
(2) In titanium and titanium alloys filed with diamond, titanium nitride was formed on the surfaces, whereas no nitride was formed when abrased with emery paper in running water.
(3) In titanium ion-etched with Ar ions, titanium carbide was formed on the surface due to the reaction with contaminated hydrocarbon and no clean titanium surface, therefore, was obtained by ion-etching.
(4) In Ti-0.16%Pd and Ti-15%Mo-0.2%Pd alloys dipped into mixed acid, the surface enrichment of the alloying elements was observed; in the former palladium was enriched in the metallic state, whereas in the latter molybdenum was enriched in the oxidation state, but no Pd3d peak was observed.
(5) In Ti-0.16%Pd, Ti-5%Ta and Ti-15%Mo-0.2%Pd alloys oxidized in air at 673 K for 600 s, the titanium oxide TiO₂ was present on outermost surfaces of the specimens, whereas in the Ti-8%Mn alloy the enrichment of manganese in the oxidation state was observed on the outer surface.