MORPHOLOGICAL EVOLUTION OF Ti SURFACES DURING OXIDATION TREATMENT

Abstract

Pure commercial titanium, a biocompatible titanium alloy and titanium samples produced by severe plastic deformation SPD) have been modified chemically to develop a thin, hydrated titanium oxide layer. The surface morphology and evolution of this morphology of four different Ti samples–-CP-Ti, Ti6Al4V, Ti-SPD1 and Ti-SPD8–-have been investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effects of metalographic etching and chemical oxidation have been examined by SEM and AFM. The coarse-grained pure Ti sample has facetted surface morphology with a characteristically smaller length scale than its grain size. The grains of the Ti6Al4V alloy were covered by a hydrated oxide layer, but the grain boundaries were etched to deep, sharp grooves. The samples produced by the SPD process have better mechanical properties, than the alloy sample, and the oxidized surfaces have a roughened surface morphology with a multiscale, smoothed hillock structure and a characteristically short length, which is very advantageous for biointegration.

Key Words:

• Atomic force microscopy (AFM)
• Biocompatibility
• Chemical oxidation
• Coating
• Energy dispersive spectroscopy (EDS)
• Equal channel angular pressing (ECAP)
• Health risk
• Hydrixiapatite
• Medical application
• Nanostructure
• Scanning electron microscopy (SEM)
• Severe plastic deformation (SPD)
• Surface treatment
• Surgical implant
• Work hardening

ACKNOWLEDGMENT

The authors thank Prof. R. Z. Valiev for providing the SPD Ti samples. The work was supported by TeT-ÖAD under contract number A-25/01, by OTKA under contract number T-037643 and by NKFP under contract number 3a0059/2002.