DRY MECHANOSYNTHESIS OF CARBONATESUBSTITUTED HYDROXYAPATITE

Abstract

Dry mechanosynthesis was used to prepare carbonate-subtituted hydroxyapatite powders via a solid-state reaction between calcium hydrogen phosphate dihydrate and calcium carbonate. The synthesized powders were characterised by x-ray diffraction, Fourier transformed infrared spectroscopy, x-ray fluorescence, elemental analysis, inductively coupled plasma analysis, scanning electron microscopy and transmission electron microscopy. Results showed that the synthesized powders were preferentially carbonatesubtituted hydroxyapatite, of the B-type, in the form of agglomerates formed after 7 hours of mechanical alloying at 400 rpm with a ball to powder weight ratio equal to 10:1. Increasing the milling duration improved the formation of the apatite phase due to the higher impact energy transference to the compounds, accelerating the kinetics of phase transformation. Chemical analysis by inductively coupled plasma method showed that the as-milled powder fulfilled the requirements of ASTM F1185-03, the standard that specifies the chemical requirements necessary for biomaterials. Consequently, the high efficiency of the process paves the way to produce commercial amounts of nanocrystalline carbonate-substituted hydroxyapatite powder, which is promising for the fabrication of bone-resembling implants.