Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel

[Display omitted] ► Successful electrodeposition of polypyrrole (PPy)/strontium HA bilayer on 316L SS. ► SEM morphology reveals porous strontium HA layer on PPy coated 316L SS. ► As-formed bilayer demonstrates enhanced corrosion protection in Ringer's solution. ► The passive film underneath the PPy layer provides effective corrosion protection. ► The bilayer coating possesses enhanced adhesion strength and hardness. Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS.