Bonding Strength, Hardness and Bioactivity of Nano Bioglass-Titania Nano Composite Coating Deposited on NiTi Nails

Mojtaba      Nasr-Esfahani; Reza      Ebrahimi-Kahrizsangi; Mohammad      Saleh Dadash; Saeed      Karbasi

doi:10.2174/157341311796196844

Abstract

In the present investigation a titania network encapsulating nano bioactive glass 58s (NBG) particulate phase is proposed as a bioceramic composite coating. The grain size of NBG particles was uniform and its nano scale (50 – 60 nm) confirmed with transmission electron microscopy (TEM). XRD pattern of NBG particles, calcinated at 600°C in air confirmed that the calcinated glass generally existed in amorphous state. Thermogravimetry (TG) curves for the bulk of NBG – Titania gel indicated that the organic and inorganic precursors have been decomposed completely before 600° C. Nickel-titanium alloy (Nitinol® ) Nails was dip-coated with NBG – Titania composite via the sol-gel route. The morphology, structure and component of the composites films were evaluated using environmental scanning electron microscope (SEM) and field emission scanning electron microscope (FESEM). Also, FTIR confirmed the presence of Si-OSi bands on the calcinated NBG-Titania films. The hardness of the prepared films was investigated using micro hardness test method. The results verified that the presence of NBG particles in titania matrix enhanced gradually the mechanical data of the prepared films (450 VHN). Direct pull-off test recorded a mean coating-substrate bonding strength larger than 16 MPa. The in vitro bioactivity of prepared films indicates that hydroxyapatite nuclei can form and grow on the surface of NBG-Titania films coated on Nitinol alloy. The present study shows that due to their excellent bioactivity, hardness and bonding strength to substrate, NBG-Titania coatings are practical biocomposite films in biomedical applications.

Keywords: Bioactive glass, Titania, Sol, –, gel preparation, Nanostructure, Nitinol®, biocomposite, Bioglass-Titania nanocomposite, NiTi Nails, Coating, Hardness, Strength, Bioactivity