화학공학소재연구정보센터
Applied Surface Science, Vol.303, 367-372, 2014
Effect of hydrothermal treatment model on stability and bioactivity of microarc oxidized titania coatings
Different types of Sr-doped hydroxyapatite (Sr-HA) nanorod arrays were prepared on microarc oxidized (MAOed) TiO2 coatings after hydrothermal treatment (HT) for 24 h in the case of different HT models, namely the MAOed TiO2 coatings to be hanged up in the autoclave without touching the HT solution (termed as H-HT) and immersed in the HT solution (termed as I-HT). The MAO+H-HT (HT in the case of HHT model) and MAO+I-HT (HT in the case of I-HT model) coatings are multilayered by nanorod-shaped Sr-HA as outer layer, Ca0.5Sr0.5TiO3 as middle layer and TiO2 as inner layer adjacent to Ti substrate. The Sr-HA nanorods on the coatings are randomly oriented, homogeneous and a similar mean diameter of 70 nm. However, the lateral spacing between the Sr-HA nanorods on MAO+H-HT coating is much smaller compared with those on MAO+I-HT coating. The effects of the HT models on the roughness, in vitro structure and bond strength stability and apatite inducing ability of the coatings were examined. AFM evaluation reveals that the coatings have a similar microscale roughness. The as-MAOed, MAO+H-HT and MAO+I-HT coatings exhibit long-term structure and adhesive strength stability as indicated by immersion tests in physiological saline solutions for 0-48 weeks, although their adhesive strengths decrease a little after immersion in physiological saline solutions, for example, to about 10.2%, 7.8% and 6.9% at 48 weeks, respectively. Furthermore, the MAO+H-HT coating can induce apatite formation after 12 h of SBF immersion due to the compacted Sr-HA nanorods layer, and the induced apatite prefers to nucleate on the basal-faceted surfaces of Sr-HA nanorods. (C) 2014 Elsevier B. V. All rights reserved.