Post-deposition heat treatments for ion beam sputter deposited calcium phosphate coatings.

Calcium phosphate coatings produced using the ion beam sputter deposition process are amorphous. To produce crystalline coatings, a series of different post-deposition heat treatments were conducted. Heat treatments conducted at temperatures less than 500 degrees C did not produce crystalline phases in the coatings. A 500 degrees C post-deposition heat treatment provided the energy required to produce a hydroxyapatite (HA)-type coating as determined using X-ray diffraction and Fourier transform IR spectroscopy (FTIR). Although post-deposition heat treatments can reduce the adhesion of a coating to its substrate, the 500 degrees C heat treatment did not decrease the coating bond strength. Heat treatments conducted at 600 degrees C were found to produce crystalline HA-type coatings but these heat treatments significantly reduced the coating bond strength. Cracks were observed on the surface of the 600 degrees C heat treated coatings. FTIR analysis revealed a new absorption band at 820 cm-1 for the 600 degrees C heat treated coatings, suggesting the formation of a new phase.