In situ synthesis of osteoconductive biphasic ceramic coatings on Ti6Al4V substrate by laser-microwave hybridization

Abstract

Microwave heating is an efficient alternative approach for synthetic chemistry with many distinctive advantages of high heating rate, selective and homogeneous heating. In this study, a new laser-microwave hybridization method, which comprises laser micropatterning, microwave heating and in situ synthesis has been developed to produce titania/hydroxyapatite/tricalcium phosphate (TiO2/HA/TCP) composite coating on titanium alloy (Ti6Al4V) substrate. The composite coating with a fine porous network microarchitecture was selectively produced on the Ti6Al4V surface by laser ablation and alkaline treatment. Using TiO2 sol-gel and mixed powders of calcium carbonate (CaCO3) and dicalcium phosphate dihydrate (CaHPO4·2H2O), the composite coating synthesized at a temperature of 800°C in a short time of 20min exhibited homogeneous microstructure, strong hydrophilicity and good adhesion strength of 34MPa. The in vitro apatite-forming capability of the coating was examined by immersing the coated Ti6Al4V specimen into a simulated body fluid (SBF) for up to 7days. Biodissolution was observed in the early stage of incubation, followed by apatite precipitation. The quantity and size of the apatite globules increased over time. After 7days of immersion, the coating surface was nearly covered by a layer of bone-like apatite, showing a significant improvement of its osteoconductive property over the uncoated sample. The laser-microwave hybridization provides an efficient route to synthesize HA/TCP based coatings for bioactivity enhancement, and serves as an effective sterilization tool for implant materials.