Preparation and characterization of novel bioactive dicalcium silicate ceramics

The beta- and gamma-dicalcium silicate (β- and γ-Ca2SiO4) ceramics were prepared by sintering β-Ca2SiO4 greens at 1100, 1300, and 1450 °C, respectively, after compacting with cold isostatic pressure. The phase transition from β- to γ-phase of polymorphic ceramics occurred at 1100-1300 °C. Bending strength and Vickers hardness of β-Ca2SiO4 ceramic sintered at 1100 °C were only 25.6 ± 3.8 MPa and 0.41 ± 0.05 GPa. In contrast, the mechanical properties of the γ-Ca2SiO4 were improved remarkably when the ceramics were sintered at 1450 °C, corresponding to bending strength, 97.1 ± 6.7 MPa; Vickers hardness, 4.34 ± 0.35 GPa, respectively. The ceramics were soaked in the simulated body fluid (SBF) for various periods were characterized by SEM, XRD, FTIR, and EDS analysis, and the results indicated that the carbonated hydroxyapatite (CHA) was formed on the surface of the ceramics within 3 days. In addition, cell attachment assay showed that the ceramics supported the mesenchymal stem cells adhesion and spreading, and the cells established close contacts with the ceramics after 1 day of culture. These findings indicate that the γ-Ca2SiO4 ceramic possesses good bioactivity, biocompatibility and mechanical properties, and might be a promising bone implant material.