Mechanical evaluation of calcium-zirconium-silicate (baghdadite) obtained by a direct solid-state synthesis route

Ca3ZrSi2O9 (baghdadite) has become a major research focus within the biomaterial community due to its remarkable in-vitro and in-vivo bioactivity. Although baghdadite seems to exhibit interesting biological properties, as yet there has been no data published concerning its mechanical properties. This lack of knowledge hinders targeting this novel bioactive material towards potential applications. In this study we prepare dense Ca3ZrSi2O9 bulk ceramics for the first time, allowing the evaluation of its mechanical properties including hardness, bending strength, Young׳s modulus, and fracture toughness. The preparation of baghdadite has been accomplished by a direct solid-state synthesis in combination with conventional sintering at 1350–1450 °C for 3 h. Our results show that samples sintered at 1400 °C exhibit the best mechanical properties, resulting in a bending strength, fracture toughness, and hardness of 98±16 MPa, 1.3±0.1 MPa m0.5, and 7.9±0.2 GPa. With a comparable mechanical strength to hydroxyapatite, but with an increased fracture toughness by 30% and hardness by 13% baghdadite is highly suitable for potential applications in non-load bearing areas (e.g. coatings or filler materials).