Digital Repository, CONVEGNO IGF XXII ROMA 2013

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Thermomechanical behaviour of alumina-mullite refractories developed by recycling industrial ceramic wastes
A. Coglitore, A. Brentari, E. Burresi, F. Mazzanti, C. Mingazzini, M. Villa

Last modified: 2013-06-27


Alumina-mullite (AM) refractories are widely used as liners for the thermal insulation of the
combustion chambers in gas turbines for power production. A complete thermomechanical characterization of
a commercial AM refractory was performed according to the international standards for dense ceramic or
ceramic composites. Four-point flexural test were carried out on standard specimens to determine the values of
Modulus of Rupture (MOR) and Young’s modulus (E), at room temperature and up to 1500 °C: this
temperature was chosen because the inlet temperature of the turbines for energy production was around
1400 °C. The most important property required to refractories for this application is the thermal shock
resistance. In order to quantify it, four-point flexural tests at room temperature after quenching were carried out
to calculate the residual MOR, according to the standard procedure for dense ceramics. The tests were
performed with temperature differences up to 1000 °C, which is comparable to operating conditions during the
turbine shutdown. New AM refractories were developed, by recycling a large amount (20 wt%) of industrial
ceramic wastes coming from gas turbine investment casting process, and also adding zircon (ZrSiO4). Also for
these materials, a thermomechanical characterization was performed, in order to compare the behaviour of the
new materials to the commercial refractory’s one. Interesting results were found about the mechanical
properties of the new materials. The refractories developed by recycling industrial ceramic wastes generally
show better mechanical and thermal shock resistance than the commercial refractory taken into account.

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