Nano-Titania Embedded Hydroxyapatite Coating by Precursor Plasma

Plasma spraying is widely used to produce coatings of Hydroxyapatite (HAP). Titania has also been added to HAP coatings to enhance the environmental protection owing to its photo-catalytic property.  The benefits of titania maximizes when it is in a nano-sized anatase form.

In this study nano-titania was synthesized in-flight using liquid precursor of titanium isopropoxide and ethanol.  The precursor was axially fed into the plasma gun via special hardware to form nano-titania particles, while HA powder was externally injected downstream. Coatings up to 200 microns thickness were deposited onto flat titanium coupons. To suppress the evolution of undesired phases in the deposit, an induction coil was used on-site to control the temperature of the target during the deposition process, inducing in-situ heat treatment. X-ray diffraction studies showed peaks of the deposit identically matching to that of the powder. As for the titania, fine particles containg both the anatase and rutile phases were observed. The influence of process parameters and the target temperature on the phase and microstructure is analyzed and presented.