Electrochemical and corrosion protection performance of Sr-HaP/PoPD coated LN stainless steel

Background Stainless steel is a common implant material used in orthopaedic surgeries. However, metallic ions are released from the implants when it placed inside the human body. Coating of biocompatible material such as strontium hydroxyapatite (Sr-HaP) is one of the methods to reduce the release of metallic ions into the body. Method In the present work, we have developed a bilayer coating namely poly-orthophenylenediamine (PoPD) on Sr-HaP deposited low nickel stainless steel (LNSS) via electrochemical deposition followed by electropolymerization methods. The Sr-HaP/PoPD coating was confirmed with Fourier transform infrared spectroscopy (FTIR) and high resolution scanning electron microscopy (HR-SEM). The corrosion protection performance of the coated LN SS specimens in Ringer's solution was investigated using potentiodynamic polarisation and electrochemical impedance spectroscopic techniques. The leach out characteristics of the coating was determined at the impressed potential. Significant findings The studies revealed that the passive film underneath the PoPD layer is acting like a shield and prevent the LN SS from corrosion. Furthermore, the potential bioactivity of LN SS is due to the presence of top porous Sr-HaP layer. Hence, the PoPD/Sr-HaP bilayer coating on LN SS substrate could be a promising material for orthopaedic implant applications.