Investigation of the crystallinity of suspension plasma sprayed hydroxyapatite coatings

Hydroxyapatite coatings were deposited on stainless steel substrates. The arc current was varied to study its effect on the coating crystallinity. The crystallinity was calculated according to the XRD patterns via Jade 6.0 software and the full width at half maximum (FWHM) of Raman peak at 962 cm−1. The FE-SEM images showed that HA coatings had rod-like nanostructures and agglomerated into microspheres. The XRD patterns indicated that the as-sprayed coatings were composed of HA and some decomposition phases. Micro-Raman spectroscopies demonstrated that the main phase in the coatings was HA. The results showed that the crystallinity was increased from 68.68% to 76.84% while the FWHM varied from 9.74 to 6.38 cm−1, when the arc current increased from 400 A to 600 A. The selected area electron diffraction (SEAD) patterns were used to analyze the crystallinity qualitatively, and the results agreed with the conclusions of XRD and FWHM of Raman peak.