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Nano‐Sized Hydroxyapatite Coatings on Ti Substrate with TiO 2 Buffer Layer by E‐beam Deposition
Author(s) -
Lee SuHee,
Kim HyounEe,
Kim HaeWon
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2006.01351.x
Subject(s) - coating , materials science , layer (electronics) , titanium , substrate (aquarium) , chemical engineering , dissolution , deposition (geology) , composite material , buffer (optical fiber) , nanometre , metallurgy , paleontology , telecommunications , oceanography , sediment , computer science , engineering , biology , geology
A nano‐sized hydroxyapatite (HA) layer was coated on a Ti substrate with a titanium oxide (TiO 2 ) buffer layer by the electron‐beam deposition method. The morphological features as well as the mechanical and biological properties of the HA/TiO 2 ‐layered coating were noticeably different from those of a conventional HA coating on Ti. The HA on the TiO 2 layer replicated the fine grain structure of the TiO 2 layer, with grain sizes of just a few tens of nanometers. The TiO 2 buffer layer was highly effective in preserving the adhesion strength of the coating layer following the heat treatment at 500°C, which was necessary to crystallize the structure. Moreover, in contrast to the HA single coating wherein severe cracking was observed under moist conditions, the HA/TiO 2 coating retained its mechanical stability under the same conditions. The dissolution of the HA/TiO 2 coating in a physiological saline solution exhibited a more favorable pattern than that of the HA single coating, with a reduced initial burst and a subsequent steady release rate. Preliminary in vitro cellular tests showed that osteoblastic cells expressed a significantly higher alkaline phosphatase level on the HA/TiO 2 coating than on the HA single coating. Conclusively, the nano‐sized HA coating with the TiO 2 buffer layer holds great promise as a bioactive coating system.