Bioactive Ti Metal with Ca-Enriched Surface Layer Able to Release Zn Ion
Preparation of bioactive titanium (Ti) metal able to release Zn2+ ions was attempted by chemical and heat treatments of Ti metal. Ti metal was soaked in 5M NaOH solution at 60 °C to form sodium hydrogen titanate (SHT) on its surface. Then, it was soaked in a mixed solution of 100 mM Ca(CH3COO)2 and 0.01 - 1 mM Zn (CH3COO)2 at 40 °C for 24 h to replace Na+ ions in SHT with Ca2+ and Zn2+ ions at given range of 0.15 to 2.95 in Zn/Ca ratio. When it was heat-treated at 600 °C for 1 h, zinc-incorporated calcium titanate (ZCT) and rutile were formed on the surface of Ti metal. The ZCT partially replaced its Ca2+ and Zn2+ ions with H3O+ ions by subsequent soaking in 1 mM acetic acid solution at 80 °C. Thus treated Ti metal formed apatite on its surface in a simulated body fluid (SBF) within 3 days, and slowly released Zn2+ ions into phosphate-buffered solution (PBS) up to 0.03 ppm. The Ti metal formed with this kind of bioactive ZCT layer on its surface is expected to be useful as orthopedic and dental implants, since it could bond to living bone sooner, by promoting formation of the surrounding bone.
Kunio Ishikawa and Yukihide Iwamoto
S. Yamaguchi et al., "Bioactive Ti Metal with Ca-Enriched Surface Layer Able to Release Zn Ion", Key Engineering Materials, Vols. 529-530, pp. 547-552, 2013