Microstructure evolution, mechanical properties and enhanced bioactivity of Ti-Nb-Zr based biocomposite by bioactive calcium pyrophosphate

Abstract

The crystalline phases, corrosion properties and bioactivity of materials play crucial factors in determining the longevity, biological interactions and osseointegration process of orthopedic replacement and implants. This paper presents the preparation, microstructure evolution, and corrosion properties and bioactive characterization of (Ti-13Nb-13Zr)-CPP (calcium pyrophosphate) composites for biomedical applications with the synergistic effects of excellent biocompatibility and mechanical properties of Ti-13Nb-13Zr alloy and bioactivity and tissue bio-mineralization of CPP ceramic. (Ti-13Nb-13Zr)-CPP composites with different CPP concentrations possessed matrix of β-Ti phase, a little residual α-Ti phase and ceramic phases (CaTiO3, CaZrO3, Ti2O, CaO and Ti5P3). Increasing the CPP concentrations, the increasing of CaTiO3, CaZrO3, Ti2O, CaO and Ti5P3 and the impediment of α-Ti to β-Ti were observed. The sintered (Ti-13Nb-13Zr)-CPP composites exhibited excellent yield strength (739–977 MPa) and compression strength (996–1509 MPa), ensuring a better behaviour as an implant material. Electrochemical tests result revealed that composites containing 0–5 wt.% CPP exhibited higher corrosion resistance and an increasing CPP concentrations (10–20 wt.%) deteriorated corrosion properties by that of porosity and defects induced by reaction between metal powders and CPP ceramic and the ceramic particles detachment. Bioactivity tests on composites showed the composites after soaking in simulated body fluid spontaneously precipitated diverse bone-like apatite layers and favorable cells affinity, indicating that composites exhibit high bioactivity and surface activity is enhanced by the CPP concentrations. The results demonstrate that (Ti-13Nb-13Zr)-CPP composites with CPP concentrations between 0 and 5 wt.% are potential biomaterials for orthopedic replacement or implants.