In vitro evaluation of apatite/wollastonite glass–ceramic nano biocoatings on 316 alloys by plasma-sprayed

Among bioactive ceramics, the apatite/wollastonite (A/W) glass-ceramic, containing apatite and wollastonite crystals in the glassy matrix, has been largely studied because of high bioactivity and used in some fields of medicine, especially in orthopedics and dentistry. However, medical applications of bioceramic are limited to non-load bearing applications because of their poor mechanical properties. Apatite/wollastonite coatings on 316 steel alloys substrates were prepared by plasma spraying and incubated in simulated body fluids for different periods to investigate the nucleation and growth of apatite on their surface. The morphology and the microstructure of the coatings were observed by scanning electron microscopy (SEM) and the phase composition was examined by X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR). The bioactivity of the coatings was evaluated by soaking the samples in a simulated body fluid (SBF) for 7 and 14 days. The results showed that carbonate hydroxyapatite can be formed on the surface of the coating soaked in SBF for 7 days. With longer immersion periods, the coating surface was covered by carbonate hydroxyapatite, which indicated that the apatite/wollastonite coating possesses good bioactivity.