New Glass-Ceramic Compound: A Novel Material
A novel material with potential applications in the dental industry was recently developed by researchers of the Otto-Schott-Institut of the Friedrich Schiller University Jena (Germany).
Researchers prepared glass-ceramic compounds made of magnesium oxide (MgO), aluminum oxide (Al2O3) and silicon dioxide (SiO2), using zirconia (ZrO2) as nucleating agent. For some experiments, they also used zinc dioxide (ZnO) or phosphorous oxide (P2O5) as additional additives.
To make these materials, the basic glass components were melted at 1580oC; then they were cooled down in controlled conditions, at a rate of 3oC/min. Subsequently, they were annealed (reheated) at a variable temperature, between 950 and 1150oC.
Excellent Mechanical Behavior
All the materials made with this procedure had a white color; depending on the amount of zirconia used, however, the level of opacity and translucency could be changed slightly. The mechanical properties of the compound could also be varied, with different annealing temperatures and with the presence of additives (ZnO or P2O5).
The materials showing the best mechanical strength (475 MPa) were made by annealing the compound for 3 hours at 1000oC, with a concentration of zirconia of about 10% weight and without any further additives. The values of microhardness and fracture toughness, on the contrary, were improved by the use of the other additives. In fact, the addition of ZnO lead to a hardness of 12.5 GPa, while a fracture toughness of 2 MPa·m1/2 was achieved using either ZnO or P2O5.
Great Potential Applications
Professor Christian Rüssel, one of the authors of this study, explained to Decoded Science:
“These materials have great potential applications in several fields, due to their high strength properties; their white color makes them suitable for use as dental materials. We want to perform more tests on their optical properties – color, opacity, translucency – to see how they can be optimized, using the correct amount of zirconia or some particular crystallization conditions.
The use of these materials for dental applications could be a valid alternative to the lithium-based ones; in fact, lithium is an element becoming always more expensive, due to its use in many other products, such as lithium-ion batteries.”
Dittmer, M., Rüssel, C. Colorless and high strength MgO/Al2O3/SiO2 glass–ceramic dental material using zirconia as nucleating agent. Journal Biomedical Materials Research B, 100B, 463-470 (2012). Accessed January 23, 2012.
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