Effect of electrolyte composition and heat treatment on corrosion resistance of coatings developed on Cp-Ti by anodisation

Abstract

ABSTRACT The present work is aimed at developing corrosion-resistant biocompatible coatings on Cp-Ti by anodisation. The coatings were developed by anodising Cp-Ti at a voltage of 60 V over a period of 60 minutes. The coatings were developed by using two different electrolytes, namely ethylene glycol solution of NH4F and an aqueous solution of H3PO4. The developed coatings were annealed at 400 °C. The wettability, surface morphology and phase composition of the samples were evaluated by contact angle goniometry, field emission-scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD), respectively. The corrosion characteristics of th samples were analysed by potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopy (EIS) in Kokubo’s simulated body fluid (SBF) environment to resemble the human blood plasma. Anodisation of the Cp-Ti resulted in the formation of nanoporous structure, which on annealing, resulted in the dwindling of the nanopores. The anodised (A and B) and annealed samples (AH and BH) exhibited better hydrophilic surfaces with enhanced corrosion resistance as indicated by the decrease in current densities of A, AH, B and BH samples by 70.6%, 84.2%, 87.4% and 94.2%, respectively, compared to the substrate, which qualifies them to be corrosion resistant and biocompatible.