Low-temperature crystallization of calcium phosphate coatings synthesized by ion-beam-assisted deposition.

Crystallization temperature of the amorphous calcium phosphate coating synthesized by ion-beam-assisted deposition successfully was decreased to 400 degrees C for the making of orthopedic implants with better qualities. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to investigate the morphological and structural evolution of the crystals in the coating during post-heat treatment. The crystallization of calcium phosphate coating is a hydroxyl-diffusion-controlled process, which is thought to be the mechanism responsible for the decrease of the crystallization temperature. In addition, the detailed crystallization process of calcium phosphate coating is elaborated in the present paper. The results show that the crystallinity of the hydroxyapatite coating can be well controlled by adjusting the post-heat-treatment time.