Function-structure-integrated Ti-HA coatings on TiNbZr with enhanced mechanical properties and bioactivity prepared by spark plasma sintering

摘要

Clinical applications of orthopedic implants require porous structure and hydroxyapatite for osseointegration and osteoinductivity. Nevertheless, contents of hydroxyapatite (HA) and high porosity will degenerate mechanical and corrosion properties of implants. Therefore, a novel function-structure-integrated (Ti-Nb-Zr)/(Ti-HA) composites with high strength, activity and porosity and low elastic modulus consisting of a high dense Ti-13Nb-13Zr core and an external micro- and macro-porous Ti-HA part were designed and fabricated. The central compact Ti-Nb-Zr alloy provides excellent mechanical properties, while the external part with appropriate characteristics of porous structure and bioactive HA, which enhances bioactivity and provides low elastic modulus. The relative density of Ti-Nb-Zr part was 92%, and the porosity of radial Ti-HA part were between 35.3% (5 wt% HA) and 40.1% (20 wt% HA). The compressive strength of composites exhibits a remarkable improvement from 248 to 421 MPa and the elastic modulus from 10.8 to 18.9 GPa. Bioactive HA and specific pores characteristics induced bone-like apatites to deposit on porous part. The homogeneity and thickness of bioactive apatite layer on composites were enhanced with the increase of HA contents. Experimental results of bone mesenchymal stem cells (BMSCs) proliferation, the HA and the pore structure make the (Ti-Nb-Zr)/(Ti-HA) exhibited good cell activity and extensibility to BMSCs. This research would offer a potential strategy for designing and preparing function-structure-integrated orthopedic implants.