Porous and Strong Bioactive Glass (13-93) Scaffolds Prepared by Unidirectional Freezing of Camphene-Based Suspensions
Scaffolds of 13-93 bioactive glass (6Na 2O, 12K 2O, 5MgO, 20CaO, 4P 2O 5, 53SiO 2; wt.%) with an oriented pore architecture were formed by unidirectional freezing of camphene-based suspensions, followed by thermal annealing of the frozen constructs to grow the camphene crystals. After sublimation of the camphene, the constructs were sintered (1 h at 700 °C) to produce a dense glass phase with oriented macropores. The objective of this work was to study how constant freezing rates (1-7 °C min -1) during the freezing step influenced the pore orientation and mechanical response of the scaffolds. When compared to scaffolds prepared by freezing the suspensions on a substrate kept at a constant temperature of 3 °C (time-dependent freezing rate), higher freezing rates resulted in better pore orientation, a more homogeneous microstructure and a marked improvement in the mechanical response of the scaffolds in compression. Scaffolds fabricated using a constant freezing rate of 7 °C min -1 (porosity = 50 ± 4%; average pore diameter = 100 μm), had a compressive strength of 47 ± 5 MPa and an elastic modulus of 11 ± 3 GPa (in the orientation direction). In comparison, scaffolds prepared by freezing on the constant-temperature substrate had strength and modulus values of 35 ± 11 MPa and 8 ± 3 GPa, respectively. These oriented bioactive glass scaffolds prepared by the constant freezing rate route could potentially be used for the repair of defects in load-bearing bones, such as segmental defects in the long bones.
X. Liu et al., "Porous and Strong Bioactive Glass (13-93) Scaffolds Prepared by Unidirectional Freezing of Camphene-Based Suspensions," Acta Biomaterialia, vol. 8, no. 1, pp. 415-423, Elsevier BV, Jan 2012.
The definitive version is available at http://dx.doi.org/10.1016/j.actbio.2011.07.034
Mining and Nuclear Engineering
Materials Science and Engineering
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