Effects of Composition on Mechanical Properties of Suspencion Plasma-Sprayed Hydroxyapatite / Titania Coating

This study aims at revealing the effect of composition on Mechanical property and microsctucture of Hydroxyapatite/Titania coating for biomedical application. Hydroxyapatite[Ca₁₀(PO₄)₆(OH)₂,HAp] is a bioceramic material used as a plasma-sprayed coating to promote osseointegration of femoral stems. Titanium and its alloy are suitable to surgical implant due to its excellent mechanical property and corrosion resistance. The HAp coatings are fabricated mostly by atmospheric plasma spraying (APS) process. However, the conventional plasma spray process requires hydroxyapatite powders with good flowability and to prepare such freely flowing powders, agglomeration processes such as spray drying, fusing and crushing are being used therefore, it’s impossible to spray small powders by the conventional method. A suspension feeding system was designed and combined with commercial plasma-spraying system. Suspension plasma spray successfully deposited homogeneous, less porosity HAp coating onto the surface of titanium substrate. Furthermore, SPS firstly could deposit composite coating of HAp/Titania. SPS could also produce oxygen-deficient types of TiO₂ coating , which can be functioned as visible-light responsive photocatalyst. Microstructure of titania coating is then characterized using XRD and Raman spectra to identify its crystral structure, and it contained oxygen-deficient phase of TiO₂ though its main crystal phase was Rutile.