Classical Bioglass®and innovative CaO-rich bioglass powders processed by Spark Plasma Sintering: a comparative study

Densification and crystallization phenomena taking place when a recently developed CaO-rich bioactive glass and conventional 45S5 Bioglass® are processed by Spark Plasma Sintering (SPS) are examined. Fully dense and wholly amorphous products can be obtained from the new glass composition at 730°C after 2min dwell time. Moreover, temperatures equal or higher than 830°C are needed to induce crystallization (α- and β-CaSiO3) in the parent glass. Conversely, Na6Ca3Si6O18 crystals are formed in sintered 45S5 samples produced under optimal conditions (550°C, 2min), although the glassy character is still preserved.Products resulting from the innovative glass powders generally display higher hardness and local elastic modulus. Devitrification also provides improvements in this system. In contrast, mechanical properties become slightly worsen when classical bioglass is processed at 600. °C. This can be probably associated to the corresponding decrease in compactness which, apparently, overcomes the benefits arising from the crystallization progress