The calcium phosphate compound (CPC) precipitating behavior of titanium phosphide surfaces obtained from heated Ti6Al4V buried in
hydroxyapatite (HA) paste was investigated using a combination of XRD, ICP and AAS. Morphological and compositional studies in the interfaces were performed by SEM and scanning Auger electron spectroscopy. The cylindrically shaped specimens were heated at 800, 850 and 900? for 1 hour in a protective argon atmosphere. The precipitated amounts of Ca and P on the specimens were measured after immersion for 2, 4, 8 weeks in 50 ml SBF using ICP and AAS. The heating process led to formation of porous surfaces and stable Ti phosphide layers in HA-Ti material interfaces. Quantities of precipitated Ca and P on the heat-treated surfaces were significantly higher than those on non treated Ti6Al4V surface, and the quantity increased with increments in pore spaces due to elevated temperature. The approximate Ca/P ratio of the CPC precipitated on non-treated Ti6Al4V is 2.2 signifying a high non-crystallinity, and the ratio of CPC formed on titanium phosphide surfaces ranged from 1.62 to 1.83. Hence, the results show that the composition and morphology in the interfaces of phosphide and oxide films show a variety of in-vitro CPC precipitation behavior. This method could be suitable for the surface modification of titanium materials which in-turn will be able to improve the biological performance of titanium implants.

Keywords: Titanium, hydroxyapatite, CPC Precpiitation, Heat Treatment, Titanium Phosphide