Microstructure evolution, mechanical properties, and enhanced bioactivity of Ti-13Nb-13Zr based calcium pyrophosphate composites for biomedical applications

Abstract

The present study reports the results of the microstructure, mechanical properties and in vitro bioactivity of the Ti-13Nb-13Zr based composite with 10 wt% CPP (calcium pyrophosphate), densified using spark plasma sintering process (SPS) at different sintering temperatures (900-1200 °C). The results show that the sintered composites mainly consist of β-Ti, α-Ti, and ceramic interphases (Ti₂O, CaTiO₃, CaZrO₃, CaO, Ti_xP_y). With the sintering temperature increasing, α-Ti and ceramic interphases gradually increase, and relative density, elastic modulus, compressive strength and yield strength of the composites also reveal an increasing tendency. However, Ti-13Nb-13Zr-10CPP composite sintered at 1000 °C exhibits high matching elastic modulus (46 GPa) and compressive strength (1617 MPa) due to uniform structure and high density. In addition, in vitro mineralization assays demonstrate the apatite-forming ability of the composite (1000 °C) and its higher surface bioactivity as compared to the Ti-13Nb-13Zr alloy. Furthermore, ROS1728 osteoblast culture evidences that the composite (1000 °C) stimulates cell adhesion and growth due to the pore characteristics and ceramic interphases. Therefore, the prepared Ti-13Nb-13Zr-10CPP composite at 1000 °C exhibits immense potential as a biomedical material.

Keywords: Bioactivity; Mechanical properties; Microstructure; Spark plasma sintering; Ti-13Nb-13Zr based composites.