Hydroxyapatite coating on titanium by thermal substrate method in aqueous solution

A new hydrocoating method (the thermal substrate method) is proposed for co ating calcium phosphates such as hydroxyapatite (HA), on titanium substrate s in an aqueous solution. Several factors (e.g., the type of ion source, th e heating time and temperature, and the surface roughness of the substrate) affected the characteristics of the precipitate formed by this method. The solution used included 3 mmol dm(-3) Ca(H2PO4)(2) and 7 mmol dm(-3) CaCl2, and its pH was adjusted to 6.5. The experimental studies were conducted un der the following conditions: temperature 45-160 degreesC, heating time 10- 20 min, and surface roughness of substrate #120-#2000 grid ground using ene rgy paper. A high quality of precipitate, whose predominant component was H A, was obtained on titanium substrates by the thermal substrate method in a n aqueous solution. No significant difference in the precipitates was found with the type of ion source. TI-ie amount of HA precipitate increased with increasing temperature and with increasing heating time. The features of t he precipitate were different, depending on the surface roughtness of the s ubstrate: HA regularly nucleated along the grooves of the rough surface (#1 20 and #400 grid), and in the case of the fine surface (#1200-#2000 grid), a uniform precipitation occurred. (C) 2001 John Wiley & Sons, Inc.