Interface characteristics changed by heat treatment of Ti materials with hydroxyapatite

The titanium materials buried in hydroxyapatite (HA) powder and HA dip coated-Ti based materials were heated and the interface was investigated for microstructure and chemical composition using a combination of scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning Auger electron spectroscopy (SAES). The cylindrically shaped specimens were heated at 800, 850, and 900 °C for 1 h in protective argon atmosphere, which led to the formation of porous surfaces. The pore spaces increased with the grain growth caused by the elevated temperature. The phosphorus concentration diffused from the HA coating layer after heating at 800 °C and increased up to 7 at.%. The phosphorus concentration obtained from this heating process was 3 times higher than that formed by heat treatment of Ti materials buried in HA powder. Observations from the interfaces heated at 900 °C revealed a high concentration of oxygen and little concentrations of P and Ca. The composition and morphology in the interfaces of phosphide and oxide films show a variety of properties. This low-cost and simple surface modification technique of titanium materials may provide a biomaterial for hard tissue replacements.