Effect of alumina bubbles with and without Al 2 O 3 coatings on the performance of lightweight Al 2 O 3 ‐MgAl 2 O 4 refractories

Abstract In this work, the effect of alumina bubbles with Al 2 O 3 coatings (CABs) and without coatings (ABs) on the performance of lightweight refractories was investigated. It showed that the addition of either ABs or CABs was beneficial to improve mechanical properties of refractories. The compressive strength for the specimens with 1 wt% ABs and CABs addition increased from ~50.5 to ~60.9 and ~70.2 MPa. The refractoriness under load was enhanced from ~1589 to ~1617 and ~1623°C. Furthermore, the results of three‐point bending tests showed significant improvement was achieved in thermal shock resistance in terms of the value of residual strength ratio from 16% to 43% for specimens with CABs addition. Meanwhile, the results of ultrasonic pulse velocity measurement indicated that there is a good consistency between two evaluation methods. In order to achieve the trade‐off between lightweight and overall performance, the introduction of CABs into lightweight refractories is feasible and effective.