Bioactive glass-ceramic scaffolds by additive manufacturing and sinter-crystallization of fine glass powders
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Andrea Zocca Division of Ceramic Processing and Biomaterials, BAM Federal Institute for Materials Research and Testing, Berlin 12203, Germany
Johanna Schmidt Dipartimento di Ingegneria Industriale, University of Padova, Padova 35131, Italy
Jens Günster Division of Ceramic Processing and Biomaterials, BAM Federal Institute for Materials Research and Testing, Berlin 12203, Germany
Paolo Colombob) Dipartimento di Ingegneria Industriale, University of Padova, Padova 35131, Italy; and Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16801, USA
Enrico Bernardoa) Dipartimento di Ingegneria Industriale, University of Padova, Padova 35131, Italy (Received 31 January 2018; accepted 9 April 2018)
Wollastonite (CaSiO3)–diopside (CaMgSi2O6) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn influenced by the powder size and the sensitivity of CaO–MgO–SiO2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800–900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which benefit their use for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed.
I. INTRODUCTION
Additive manufacturing (AM) of glasses and, in general, of silicate ceramics specifically aimed at obtaining highly porous bioactive scaffolds for bone tissue applications, is still an open issue. The first experiences were presented in the review paper by Gmeiner et al.,1 according to which the approaches can be roughly divided into technologies for indirect printing and a)
Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/editor-manuscripts/. DOI: 10.1557/jmr.2018.120
technologies for direct printing. Indirect printing corresponds to the manufacturing of polymeric replicas, e.g., by means of stereolithography, for the gel-casting of glass powders,2,3 in analogy with what was done with other bioceramic powders.4,5 Sintering occurs after template removal and burn-out of organic additives. The direct fabrication of glass-base
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