Abstract :
High-resolution electron microscopy was used to investigate two types of titanium-oxide
interface structures. The first type was generated by thermal oxidation during the
degassing process, which is one step in the process of porcelain-fused-to-metal systems.
The thermal oxidation was performed for 1 min at a temperature of 1073 K in a porcelain
furnace under a reduced pressure at 27 hPa. Columnar and granular rutile oxide formed on
the titanium, and the surface oxide layer was almost 1 μm thick. On an atomic scale, the
crystal size of the rutile adjacent to the interface decreased about 10 nm. In addition, a very
thin transitional layer 2–3 nm thick formed at the titanium-oxide interface. The crystal
structure of the thin layer seemed to be the TiO phase with a NaCl-type structure. The
interface between the hcp titanium and TiO phases was coherent through the close-packed
planes ((0 0 0 2)hcp and (1 1 1)TiO). Partial coherency was observed at the interface between
the TiO and TiO2 phases. The second type of titanium-oxide interface was generated by
anodization on a screw-type titanium implant. The morphology of the surface suggested
that the titanium implant had been treated by spark anodization. The surface oxide, which
was estimated to be about 10 μm thick, was a mixture of the anatase-type TiO2 phase and
the amorphous phase. The crystal size of the anatase varied from less than 10 nm to more
than 100 nm. A phosphate anion was concentrated in the amorphous phase. Between the
surface oxide and the titanium base, macroscopic defects like cracks and voids were
observed. Microscopic observation could not confirm the formation of a clear interface and
lattice coherency between the titanium and oxide as a result of the degassing process.
C 2005 Springer Science + Business Media, Inc.
