Effects of magnesium substitution in hydroxyapatite and its coating on stainless steel 316L

Abstract

In this work, hydroxyapatite (HA) and magnesium doped hydroxyapatite nanopowder (Mg2HA and Mg4HA) were
synthesized by the sol-gel method using precursor calcium nitrate tetra-hydrate (CNT) for calcium, tri-ethyl phosphate (TEP)
for phosphorous and magnesium nitrate hexa-hydrate for magnesium and their coatings were deposited on stainless steel
316L using dip coating technique. The powders were calcined at 400ºC and coated samples were sintered at 400ºC. The
Ca/P ratio of the synthesized HA and (Ca+Mg)/P ratio of Mg2HA and Mg4HA nanoparticles were maintained in the range
of 1.58–1.67. Various characterization techniques were used to study the compositional structure, functionality and phase
changes of powders and microstructure of coatings by using XRF, FTIR, XRD and FE-SEM respectively. The mechanical
properties of coatings like surface roughness, micro hardness and adhesion strength were also characterized.
Potentiodynamic linear polarization was also done to study the corrosion behavior of coated samples. XRF confirms that
magnesium has been doped successfully and HA, Mg2HA and Mg4HA coatings were successfully and uniformly deposited on
316L SS. Mg4HA showed the good mechanical behavior like its micro hardness and adhesion strength was high and low
surface roughness. Corrosion study reveals that Mg4HA has good corrosion resistance.