Elastic and Mechanical Fatigue at High Temperatures of High-Alumina Castables with Addition of Partially Stabilized Zirconia
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This work evaluates the impact of added zirconia on the thermomechanical and thermoelastic fatigue properties of high-alumina refractory castables. Three testing scenarios are presented in the study: 1) Resonant Frequency Damping Analysis (RFDA) after cyclic temperature changes with and without mechanical load, 2) Refractoriness under Load (RuL) tests, and 3) results of abrupt temperature shifts between two high temperatures in a special thermal shock furnace. The tested refractory formulations were a reference castable based on tabular alumina and two castables each containing 13.75 mass-% of zirconia. The formulations of the zirconia castables had an addition of either fully-stabilized zirconia doped with 8 mol-% yttria (Y-FSZ) or partially-stabilized zirconia doped with 3 mol-% calcia (Ca-PSZ). The Y-FSZ castable displayed elastic and mechanical behaviour by means of RFDA and RuL similar to the reference sample and had good recovery after thermal shock testing. The Ca-PSZ formulation showed some beneficial toughening through energy dissipation of progressing cracks, but after cooling exhibited the matrix fracturing influence of the martensitic zirconia phase transformation which would negatively impact service life of the refractory.
KeywordsYoung’s modulus thermomechanical properties resonant frequency damping analysis thermal shock resistance transformation toughening
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