Glass - Back to the Future!



Presenting Author:
Enrico Bernardo
<enrico.bernardo@unipd.it>

article posted 16 Dec 2015


Enrico Bernardo is a professor of Materials Science and Technology at the Department of Industrial Engineering, University of Padova, Padova, Italy. He graduated from the University of Padova with a degree in materials engineering in 2000. He received a PhD degree in materials engineering from the University of Bologna in 2004. He later worked at the University of Padova as post-doc research assistant, until 2007. In October 2007 he was appointed as assistant professor at the University of Padova, confirmed in 2010. In November 2014, he was appointed as associated professor. He was awarded the Pfeil Award (The Institute of Materials, Minerals and Mining, London, UK) in 2010 and 2015. He published more than 100 papers in peer-reviewed journals (h=22), 4 book chapters and holds 2 national patents. He presented more than 10 invited talks at international conferences in the field of ceramics.

Enrico Bernardo's research interests include high-value ceramic (mainly glass-based) products from the reuse of hazardous industrial and natural waste and advanced silicate ceramics from preceramic polymers combined with micro- or nano-sized fillers.






Novel route for bioactive glass-ceramics based on
preceramic polymers and reactive oxide fillers

Enrico Bernardo*, Laura Fiocco, Hamada Elsayed
Department of Industrial Engineering, University of Padova


Glass-ceramics based on Ca-Mg silicates are receiving a growing interest for biomedical applications, mainly due to their bioactivity and biocompatibility.

This paper concerns the feasibility of wollastonite-diopside glass-ceramics by a novel route, based on the direct firing of mixtures of silicone resins with CaO and MgO precursors, comprising also sodium phosphate as minor filler.

The resulting phase assemblage, comprising silicate crystals immersed in a glassy phase, mimics that available from the sinter-crystallization of the glass with the same CaO-MgO-SiO2-Na2O-P2O5 overall composition; in addition, the phase assemblage does not change for silicone-based mixtures comprising the same glass as further filler, in different contents (from 30 to 70 wt% of the final ceramic).



The silicone-based mixtures, besides offering advantages in the synthesis, are particularly interesting for the application of additive manufacturing (AM) techniques, in turn aimed at the fabrication of highly porous 3D-scaffolds. As an example, direct ink writing of silicone/fillers mixtures leads to reticulated wollastonite-diopside scaffolds with a remarkable compressive strength, ranging from 3.5 to 5.3 MPa, for a total porosity between 65 and 75%.



Operating with sodium phosphate hydrate, glass-ceramic foams are easily achieved by water release, at 300-350 C, from the dehydration of the same fillers, before ceramization upon firing at high temperatures (Fig.3). The foams are comparable, in terms of strength and porosity, with reticulated scaffolds.