ANTIBACTERIAL EVALUATION OF SOFT AND HARD COATINGS FOR BIOMEDICAL APPLICATIONS

Abstract

This paper reports on the mechanical, microstructure, phase analysis and antibacterial activity of two
different wear-resistant and osseointegration coatings performed on Ti-6Al-4V alloys for orthopedic
applications. The powders of following compositions were sprayed using atmospheric plasma spray
process onto Ti-6Al-4V alloy a) alumina-titania, [AT] b) yttrium stabilized zirconia [YSZ], c) bilayered
AT/YSZ, d) bilayered YSZ/AT, e) Hydroxyapatite [HaP], f) TiO2 g) HaP [30%] + TiO2 [70%], h) HaP [70%]
+ TiO2 [30%] and i) HaP [50%] + TiO2 [50%]. The coatings were characterized using X-ray diffraction
(XRD), Scanning electron microscope (SEM) and surface roughness measurement. In addition,
microindentation hardness measurements and scratch strength measurements were also performed.
Amongst the various coatings AT, BL AT/YSZ and 3H7T exhibited higher hardness values and BL
YSZ/AT and 3H7T offered higher scratch resistance. Antibacterial testing was also performed on all the
coatings. The wettability studies reveal the soft coating to be hydrophilic and hard coating as
hydrophobic. Comparatively, there were less S. aureus on plasma sprayed soft coatings deposited on Tialloys
compared with hard coatings after 18 hours of culture respectively. From the results, 3H7T, AT and
BL AT/YSZ have less number of bacterial colonies adhered to its surface.