Corrosion and bioactivity evaluation of nanocomposite PCL-forsterite coating applied on 316L stainless steel

- Novel nanocomposite PCL-forsterite coating was developed on 316 LSS using dip-coating technique.
- Nanocomposite coatings exhibited superior resistance to corrosion attack than pristine PCL.
- In vitro bioactivity of the nanocomposite coatings demonstrated enhanced bioactivity with increasing forsterite content.

The weak corrosion resistance is the main drawback of 316L stainless steel (316 LSS) as implant materials for biomedical applications. Therefore, surface modification of 316 LSS with various coating techniques, which could simultaneously improve the corrosion resistance, biocompatibility and bioactivity is necessary. The present study was aimed to design a novel nanocomposite poly(ε-caprolactone) (PCL)-forsterite (Mg2SiO4) coating on 316 LSS using dip-coating technique to improve bioactivity and corrosion resistance. Furthermore, the effects of various concentrations of forsterite nanopowder (0, 1, 2.5 and 5 wt.%) on the morphology, contact angle, roughness, in vitro bioactivity and corrosion resistance were investigated. Results confirmed the successful formation of crack-free nanocomposite coating on 316 LSS. Moreover, in vitro bioactivity of the nanocomposite coatings demonstrated enhanced Ca-P precipitation on the surface of samples with increasing forsterite content. The corrosion evaluation considered by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) demonstrated that while PCL and PCL-forsterite nanocomposites coatings showed improved corrosion resistance compared to 316 LSS, nanocomposite coatings consisting of 1 wt.% forsterite nanopowder exhibited superior resistance to corrosion attack than pristine PCL, and were able to survive severe localized corrosion in physiological solution. It is envisioned that the proposed nanocomposite can be useful for orthopedic applications in the future.