Novel hydroxyapatite-forsterite-bioglass nanocomposite coatings with improved mechanical properties

The purpose of this work was fabrication and evaluation of mechanical properties of hydroxyapatite-forsterite-bioactive glass nanocomposite coatings. The novel hydroxyapatite-forsterite-bioactive glass nanocomposite coating on 316L stainless steel (SS) was prepared via a sol-gel process. The X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray analysis (EDX) techniques were used to investigate the microstructure and morphology of the coatings. The local mechanical properties, e.g. nano-hardness, elastic modulus and fracture toughness of four type coatings with different amounts of forsterite, were determined by nano-indentation method using load and displacement data. The nano-indentation tester was equipped with Atomic Force Microscopy to image the indenter mark. The crack-free and homogeneous nanocomposite coatings with no observable defects were prepared. The coatings showed the hardness and elastic modulus values in the range of 2.4-3.4 (GPa) and 46-96 (GPa), respectively. The fracture toughness values of nanocomposite coatings also varied in the range of 0.56-0.972 (MPa m(0.5)). The results showed that the elastic modulus, hardness and fracture toughness values of prepared composite coatings increased with increase in forsterite amounts. Results suggested that novel composite coatings might be potentially useful for biomedical applications especially as an implant coating for hard tissue treatment. (C) 2010 Elsevier B.V. All rights reserved.