Biomimetic hydroxyapatite coating on Ti6Al4V induced by pre-calcification

摘要

Hydroxyapatite (HA) coatings on titanium alloy (Ti6Al4V) were produced by a biomimetic method. After cleaning, Ti6Al4V plates were etched with an acid mixture to obtain microporous and rough surfaces. The samples were then treated with a saturated solution of Ca(OH)_2 at boiling temperature for 4 hours. This treatment induced the deposition of a calcium-rich layer over Ti6Al4V, due to the retrograde solubility of Ca(OH)_2 with increasing temperature. Following pre-calcification, Ti6Al4V samples were treated in the temperature range 50-600 deg C and studied by scanning electron microscopy (SEM) together with energy dispersive analysis for X-ray (EDAX), Thermal analyses (TGA), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FT-IR). After heating at 400 deg C, the calcium-rich layer became dense and well adhered to the Ti6Al4V substrates. The untreated and pre-calcified samples were soaked for 2 days at 37 deg C in a calcium phosphate super-saturated (CPS) solution buffered at pH 7.4. SEM/EDX, FT-IR spectroscopy and thin-film X-ray diffraction (TF-XRD) showed uniform and well-adhered HA layer of about 20 mu m in thickness on pre-calcified Ti6Al4V samples. These results show the potential of this biomimetic method for coating medical implants with an osteo-conductive HA layer.