In-vitro electrochemical and bioactivity evaluation of {SS316L} reinforced hydroxyapatite functionally graded materials fabricated for biomedical implants

By Akmal, Muhammad; Hussain, Muhammad Asif; Ikram, Haris; Sattar, Tahir; Jameel, Sarah; Kim, Ju Young; Khalid, Fazal Ahmad; Kim, Jung Won
Published in Ceramics International NULL 2016

Abstract

Abstract Three sets of {FGMs} of stainless steel 316L (SS) reinforced with micro-, nano- and mixed (1:1 mass ratio) hydroxyapatite (HA) were fabricated by powder metallurgy route. The concentration of the {HA} was varied from 0 to 20 wt% with the increment of 5 wt% in all sets to strengthen the discrete layers of FGMs. The sintered densities along the discrete layers of {FGMs} continually decreased as a function of {HA} content which enhanced the bioactivity of the {FGMs} towards the end with high content of HA. All {FGMs} experienced an excellent corrosion response in the 0.9% NaCl solution with high passivity. Heavy diffusion of chromium (Cr) form {SS} to {HA} made the matrix Cr deficient. The chromium depletion regions around the interface of {SS} and {HA} caused an active corrosion behavior of {FGMs} in 0.1 M {HCl} solution. {FGMs} with micro-sized {HA} demonstrated the better corrosion properties than that of other FGMs. After being immersed in the simulated body fluid (SBF) solution for 7 days, the apatite layer formed on the surface of {FGMs} with micro-sized {HA} had a mature spherical morphology and leaf like shape for the other two FGMs. The apatite morphology and gained weight results proved the highest bioactivity for micro-sized {HA} reinforced FGMs.

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