+1 Recommend
0 collections
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Extension of the ‘Inorganic Gel Casting’ Process to the Manufacturing of Boro-Alumino-Silicate Glass Foams

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          A new technique for the production of glass foams, based on alkali activation and gel casting, previously applied to soda-lime glass, was successfully extended to boro-alumino-silicate glass, recovered from the recycling of pharmaceutical vials. A weak alkali activation (2.5 M NaOH or NaOH/KOH aqueous solutions) of fine glass powders (below 70 µm) allowed for the obtainment of well-dispersed concentrated aqueous suspensions, undergoing gelation by treatment at low temperature (75 °C). Unlike soda-lime glass, the progressive hardening could not be attributed to the formation of calcium-rich silicate hydrates. The gelation was provided considering the chemical formulation of pharmaceutical glass (CaO-free) to the formation of hydrated sodium alumino-silicate (N-A-S-H) gel. An extensive direct foaming was achieved by vigorous mechanical stirring of partially gelified suspensions, comprising also a surfactant. A sintering treatment at 700 °C, was finally applied to stabilize the cellular structures.

          Related collections

          Most cited references 34

          • Record: found
          • Abstract: found
          • Article: not found

          In vitro dissolution of melt-derived 45S5 and sol-gel derived 58S bioactive glasses.

          Effects of powder type, particle size (5-20 microm; 90-300 microm; 90-710 microm), and type of dissolution medium on the dissolution behavior of bioactive glasses were investigated in vitro using melt-derived 45S5 and sol-gel derived 58S bioactive glass powders. Dissolution studies were performed in simulated body fluid and in alpha-MEM based cell culture medium at 37 degrees C under dynamic conditions (1 Hz) for periods of 30 min, 1, 2, 4, 8, 17, and 22 h. The concentrations of elements dissolved from the glasses were evaluated using inductively coupled plasma analysis. The reacted powders were analyzed for bioactivity using Fourier transform infrared spectrometry to observe the formation of a calcium phosphate layer on the surface. The non-porous surfaces of melt-derived 45S5 glass powders exhibited lower dissolution rates and rate of surface layer formation than 58S gel-glass powders. The rates of dissolution for both types of powders were lower in culture medium, compared to simulated body fluid, and increased as the particle size decreased. Thus, particle size range, glass type, and powder volume fraction can be used as a means to control the release rate of active ions that stimulate the gene expression and cellular response for tissue proliferation and repair. Copyright 2002 Wiley Periodicals, Inc.
            • Record: found
            • Abstract: not found
            • Article: not found

            Mid-infrared spectroscopic studies of alkali-activated fly ash structure

              • Record: found
              • Abstract: found
              • Article: not found

              29Si NMR study of structural ordering in aluminosilicate geopolymer gels.

              A systematic series of aluminosilicate geopolymer gels was synthesized and then analyzed using 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) in combination with Gaussian peak deconvolution to characterize the short-range ordering in terms of T-O-T bonds (where T is Al or Si). The effect of nominal Na2O/(Na2O + K2O) and Si/Al ratios on short-range network ordering was quantified by deconvolution of the 29Si MAS NMR spectra into individual Gaussian peaks representing different Q4(mAl) silicon centers. The deconvolution procedure developed in this work is applicable to other aluminosilicate gel systems. The short-range ordering observed here indicates that Loewenstein's Rule of perfect aluminum avoidance may not apply strictly to geopolymeric gels, although further analyses are required to quantify the degree of aluminum avoidance. Potassium geopolymers appeared to exhibit a more random Si/Al distribution compared to that of mixed-alkali and sodium systems. This work provides a quantitative account of the silicon and aluminum ordering in geopolymers, which is essential for extending our understanding of the mechanical strength, chemical and thermal stability, and fundamental structure of these systems.

                Author and article information

                Materials (Basel)
                Materials (Basel)
                14 December 2018
                December 2018
                : 11
                : 12
                [1 ]Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy; acacio.rinconromero@
                [2 ]National Research Council of Italy (CNR), Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), Corso Stati Uniti 4, 35127 Padova, Italy; sergio.tamburini@
                [3 ]Institute of Physics of Materials (IPM), Žižkova 22, 61662 Brno, Czech Republic; taveri@ (G.T.); idlouhy@ (I.D.)
                [4 ]CEITEC—Central European Institute of Technology, Masaryk University, Kamenice 5, 62500 Brno, Czech Republic; jaromir.tousek@
                Author notes
                [* ]Correspondence: enrico.bernardo@ ; Tel.: +39-049-827-5510; Fax: +39-049-827-5505
                © 2018 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (



                Comment on this article