A comparative study on surface morphology and electrochemical behaviour of hydroxyapatite-calcium hydrogen phosphate composite coating synthesized in-situ through electro chemical process under various deposition conditions

Coating surface energy and morphology play an essential role to decide on cell attachment and subsequent faster-uniform-interconnected cell growth over the coated orthopaedic metallic implant surfaces. It has been observed that during the process of electro-chemical deposition, the in-situ formed bond energy and deposited morphology greatly depend on few controllable process parameters namely reaction over potential, pulsed time and cathode current density. Keeping in view of this, this work aimed to study and compare the surface morphology and electrochemical corrosion resistance behaviour with respect to various depositions kinetics and nucleation mechanism achieved with the help of variable current density, voltage and time. SEM micrographs of the electrodeposited surfaces depict the formations of altogether different structures of coating surfaces, varying from surface parallel flakes to concentric bars along with sub-micron dots and nano pores on its surfaces. It is observed that with increasing nucleation rate vis-a-vis increasing deposition potential, the presence of calcium orthophosphate phase is decreased along with increased rate of hydroxyapatite phase in the coating. The presence of various phosphate bond structures is evident from IR spectroscope, which seems to be accountable for the formation of various morphologies along with the varying structure of hydroxyapatite. The electrochemical impedance spectroscopy study under contact with simulated body fluid (SBF) compared their performance regarding corrosion resistance capability of coating surface after implantation in the human body.