Effect of Growth Conditions on the Structural Properties of Calcium Phosphate Coatings Prepared in the System CaCl2-KH2PO4-KOH-HCl-H2O

The effect of growth conditions (supersaturation, relative concentrations of precursors, solution pH, and process duration) on the phase composition and structural properties of calcium phosphate coatings is studied. The results are used to determine the concentration boundary of metastable, supersaturated solutions at 37DGC and a Ca/P molar ratio of 1.67 (hydroxyapatite stoichiometry). High supersaturations are shown to result in the growth of mixed-phase coatings: hydroxyapatite + octacalcium phosphate. At low supersaturations, single-phase hydroxyapatite coatings are obtained. The coatings consist of preferentially oriented nanocrystallites, independent of the growth conditions. The texture of the coatings and the size of the nanocrystallites are most sensitive to the growth duration.