Microwave processing of functionally graded bioactive materials

A functionally graded material (FGM) that can function gradually with respect to bone tissue was fabricated by microwave processing by gradually changing the composition of calcium phosphates from the surface to the interior. Silver oxide (5 and 10 mol.%) was spread on the surface of compact hydroxyapatite (HA) powder and exposed to microwave irradiation. The sintered samples were found to contain tricalcium phosphate (β-TCP) and metallic silver (Ag) along with HA as evidenced by X-ray powder diffraction (XRD) study. The content of TCP and Ag gradually decreases with increasing depth from the surface. The FGMs formed by both microwave processing and by conventional heat treatment at 900 °C for 12 h with 5% Ag2O were compared. The microwave processed FGM indicated more amounts of TCP and Ag on the surface and suggests the possibility of greater compositional control in FGM fabrication by microwave processing. © 2002 Elsevier Science B.V. All rights reserved.