SiO2- MgO-3CaO.P2O5- K2O Glasses and Glass-Ceramics: Effect of Crystallisation on the Adhesion of SBF Apatite Layers

In this work glasses with nominal molar compositions 0.45SiO 2-(0.45-x)MgO-xK 2O- 0.1(3CaO.P 2O5) (x=0 and 0.09) were heat-treated according to adequate time- temperature schedules to obtain glass-ceramics (GCs) with phosphate phases. The GCs wer e immersed for different periods of time in SBF at 37oC. The morphology, crystallinity, and adhe sion of the apatite layers thus formed are compared and discussed for the glasses and the GCs. A dhesion measurements were performed for the GCs using the scratch test technique. Distinct adhesion behaviours of the newly formed apatite layers to the substrate were observed when the G Cs composition is K-free or when it contains K. Adhesion parameters for the apatite coating on the K-cont aining GCs showed to be affected by the immersion time in SBF but were not time-dependent in the case of the K-free GCs.