45S5 bioactive glass coatings by atmospheric plasma spraying obtained from feedstocks prepared by different routes

Abstract

Abstract45S5 bioactive glass powders with the following composition: 45 wt% SiO2, 6 wt% P2O5, 24.5 wt% CaO and 24.5 wt% Na2O were melted and quenched in water to obtain a frit. The frit was milled using two different routes: dry milling followed by sieving to obtain glass particles, and wet milling followed by spray drying to obtain a powder comprising porous agglomerates. All feedstocks showed adequate characteristics that make them suitable to be deposited by atmospheric plasma spraying. The powders and coatings were characterised by field-emission gun environmental scanning electron microscope and X-ray diffraction. The roughness and the contact angle of the coatings were also determined. The bioactivity of the powders and coatings was assessed by immersion in Simulated Body Fluid. It was found that bioactive glass prepared from bioglass frit by dry milling exhibited similar bioactivity as that of a commercial bioactive glass. All coatings produced showed good adhesion to the substrate as well as suitable surface properties to ensure efficient contact with body fluid. Regardless the characteristics of the feedstocks or plasma spray conditions used, all coatings were exclusively made up of an amorphous phase. On the other hand micrographs revealed that the characteristics of the feedstock strongly impact on the final coating microstructure. The most homogeneous microstructure was obtained when the feedstock was prepared by fine dry grinding of the frit. For this coating the formation of a bioactive layer was also proved by Fourier transform infrared spectroscopy and X-ray diffraction.

Bioactive Glass Applications in Dentistry

“…Adjustment of glass TEC is achievable by increasing the amount of silica, or partial substitution of CaO by MgO and Na 2 O by K 2 O [177,178]. Several methods of surface deposition have been investigated in the pursuit of a reliable BAG coating of DIs, including glazing [177,179,180,181], sol-gel deposition [182,183], electrophoretic deposition [184,185], pulsed laser deposition [186,187], ion-beam [188], and radio-frequency magnetron sputtering [189,190,191]. The radio-frequency magnetron sputtering (RF-MS), which yields a coating with excellent adherence and purity even in complex geometrical objects, seems promising [192,193].…”

Bioactive Glasses and Glass-Ceramics for Healthcare Applications in Bone Regeneration and Tissue Engineering

“…The benefits that could emerge from the delineation of an implant coating design based on bioactive compounds that are superior to HA (i.e., bioactive glasses with a higher index of bioactivity), explains the intensive research performed worldwide in the last period [211,331,332,333]. Consequently, a wide palette of deposition methods [334] has been explored over the years to achieve this conceptual desiderate (i.e., a mechanical and biological reliable bioactive glass implant coating layer), amongst which the most prominent fabrication techniques are: (i) enamelling/glazing [335,336,337,338], thermal spray [339,340,341,342], and electrophoretic deposition [343,344,345,346] for thick coatings (>5 µm—hundreds of µm), and (ii) sol-gel [347,348,349,350], pulsed laser deposition [351,352,353,354,355], and ion-beam [356,357] and radio-frequency magnetron [151,358,359,360,361,362,363,364]) sputtering for thin films (<5 µm).…”

Glass-based coatings on biomedical implants: a state-of-the-art review

“…Atmospheric plasma spraying was also experimented to produce 45S5 Bioglass coatings on AISI 304 steel flat substrates [62].…”