Mechanically strong and bioactive carbon fiber-SiC nanowire-hydroxyapatite-pyrolytic carbon composites for bone implant application

Carbon fiber-SiC nanowire-hydroxyapatite-pyrolytic carbon composites (CHS) composed of carbon fiber, hydroxyapatite (HA), SiC nanowires (SiCnws) and pyrolytic carbon (PyC) were prepared by sol-gel, heat treating, electrochemical deposition (ECD) and isothermal chemical vapor infiltration (ICVI) for bone implant application. The morphology, microstructure and the composition of CHS were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The mechanical properties of CHS were tested and compared with the traditional bone implant materials. The in-vitro bioactivity was evaluated by testing the cell morphology, cell proliferation and cell differentiation. The results show that SiCnws and HA are distributed uniformly inside the CHS. SiCnws are attached on the carbon fibers. The diameter of the SiCnws is around 250 nm and the length is more than 100 μm. HA could grow on the surface of both SiCnws and carbon fibers, forming a brush shape. The flexural strength, shear strength, out-of-plane and in-of-plane compressive strength of CHS are 127 MPa, 90 MPa, 169 MPa and 213 MPa, respectively. The elastic modulus of CHS is 7.2 GPa. The mechanical properties of CHS are similar to those of cortical bone. In-vitro cell test shows that CHS has excellent cell proliferation and cell differentiation. CHS possessing good mechanical and biological performances may have potential to be applied for bone implant materials.