Mechanical and biological properties of atmospheric plasma-sprayed carbon nanotube-reinforced tantalum pentoxide composite coatings on Ti6Al4V alloy

Abstract

Ta2O5 coatings containing 0, 3, 5 and 7 vol% multi-walled carbon nanotubes (CNTs) were deposited on Ti6Al4V substrates by atmospheric plasma spraying (APS). The addition of CNTs had no obvious effect on the surface morphology and roughness of the coatings, but increased the coating porosity. The coatings consisted primarily of β-Ta2O5 phase, a small amount of α-Ta2O5, and minor C peaks corresponding to the CNTs. As the CNT content increased, the elastic modulus (E) and indentation fracture toughness also increased. However, the higher CNT content increased the coating porosity and reduced the microhardness. Following immersion in simulated body fluid (SBF) for 14 days, the surfaces of all the coatings were completely covered with hemispherical bone-like apatite. Furthermore, after incubation in osteoblast-like osteosarcoma MG-63 cell culture for 7 days, all of the coatings showed excellent cell attachment, growth and spreading. Overall, the present results show that the addition of CNTs to Ta2O5 raw powder improves the indentation fracture toughness of the resulting coatings without degrading their biological properties.