Suspension Plasma-Sprayed Fluoridated Hydroxyapatite/Calcium Silicate Composite Coatings for Biomedical Applications

A novel fluoridated hydroxyapatite/calcium silicate (FHA/CS) composite coating deposited via suspension plasma spraying has been designed to improve the bonding strength between coating and substrate and to provide a suitable dissolution rate for faster initial bone fixation. Composite coatings with different ratios of FHA to CS were fabricated on Ti substrates by changing the composition of the suspension. The thicknesses of the composite coatings ranged from 75 to 92 μm with porosity of 7.4-8.3%. When the ratio of FHA to CS is 3:7, the composite coating shows the highest bonding strength and dissolution rate. The in vitro bioactivity of the coatings was characterized by evaluating their apatite-forming ability after immersion in simulated body fluid (SBF). The results show that the composite coatings possess strong reactivity after immersion in SBF. The antibacterial behavior of the coatings was also examined by observing the number of viable bacteria after incubation with the composite coatings; the data show that the proliferation of Staphylococcus aureus can be inhibited. Given the combination of high bonding strength, good chemical resistance, excellent apatite-forming ability and antibacterial activity, the FHA/CS composite coating should be a very promising coating material for implants.