An algorithm for preparing bioactive fluorinated hydroxyapatite coatings by sol gel technique

Fluorinated hydroxyapatite [Ca-10(PO4)(6)(OH)(x)F1-x] implantologic structures could constitute an alternative to classic hydroxyapatite [Ca-10(PO4)6(OH)21 ones in medical applications due to their bioactivity and low solubility. Bioactive apatites are usually used as coatings onto surface of biocompatible metals, leading to implants which take advantage of the coating's bioactivity and good mechanical properties of metals. In this work, powders and apatite type films were prepared on Ti6Al4V medical grade alloy using three sol-gel chemical routes by mixing different calcium and phosphorous precursors Ca(NO3)2, P2O5 and C6H15PO3, and two fluoride reagents: HPF6 and NH4F. The resulting calcium phosphates and fluorapatite/hydroxyapatite solid solution (FHA) compounds were investigated by SEM, XRD and evaluated in vitro in SBF Kokubo solution. An efficient preparation algorithm was designed for the Ca(NO3)(2+) C6H15PO3+ NH4F chemical route which produced monophasic powders with a high crystallinity degree. This chemical route led to FHA sol-gel coatings with bioactive potential.