Plasma-sprayed coatings of 62W bioactive glass: Mechanical properties and in vitro behavior

Bioactive glasses, due to their chemical and biological properties, are promising materials for being used in orthopedic applications. In this study, coatings of the novel 62W glass, with a composition in the system SiO2CaO-P2O5-MgO, were analyzed. The 62W feedstock powder was prepared from a mixture of reagents by the meltquenching route and deposited onto titanium alloy substrates by atmospheric plasma spray (APS) technique. The cross-section and the phase of the coatings were analyzed by scanning electron microscopy and X-ray diffraction. Mechanical and in vitro tests were conducted on the obtained coatings to evaluate their bioactive ability. The results of the cross-sections show dense coatings with the absence of the characteristic pores that appear when spraying the usual bioactive glasses. The obtained coatings present a bond strength of 32 +/- 3 MPa with the substrate without crystalline phases on the microstructure. The presence of magnesium oxide in the composition favours the glass's processing and increases its crystallization temperature and, thus, the proper stacking of the deposited particles. The bioactive capacity of the 62W coatings was demonstrated at short periods after in vitro evaluation in SBF and TRIS/HCl solutions. The study reveals the potential use of 62W glass coatings for bone implant applications.