Effect of BaO Addition on Densification and Mechanical Properties of Al2O3-MgO-CaO Refractories

Lei Liu,Min Chen,Xueliang Yin,Wenjie Sun,Lei Xu

doi:10.3390/met6040084

Abstract

Considering the requirement for a reduction of refractory consumption, the present work investigated the fabrication of Al2O3-MgO-CaO-based refractory with BaO addition by means of solid-state reaction sintering. The effect of BaO addition on densification and the properties of the refractory were also discussed. Results indicated that the formation of calcium hexaluminate (CaO·6Al2O3, or CA6) grains with a high aspect ratio in the alumina-rich zone depressed the densification of the sample without BaO addition, resulting in a higher apparent porosity of 21.2%. When 6 wt. % BaO was added, a new phase of Ba2Mg6Al28O50 (BAM) with a lower aspect ratio was formed and the densification of the sample with an apparent porosity of 5.52% was promoted. In addition, mechanical performance was significantly improved due to an increase in compactness and modification of the microstructure. The cold compressive strength increased from 348 MPa to 569 MPa and the flexural strength increased from 178 MPa to 243 MPa by addition of 6 wt. % BaO. Meanwhile, the breadth of the widest crack after the thermal shock test decreased from 7 μm to 1 μm in the refractory.

Highlights

Materials designed in the alumina-rich zone of the Al2 O3 -MgO-CaO system have been widely used as steel ladle linings [1]
Al2 O3 -MgO-CaO system materials with BaO addition were fabricated by solid-state reaction sintering to improve their densification and mechanical properties
When BaO was introduced to Al2 O3 -MgO-CaO system materials, the new phase BAM was formed and the amount of MA decreased slightly

Summary

Introduction

Materials designed in the alumina-rich zone of the Al2 O3 -MgO-CaO system have been widely used as steel ladle linings [1]. ZrO2 dissolves into CA6 grain lattice in the form of a solid solution by replacing Al3+ to promote sintering and improve densification, the CA6 grains showed a more equiaxed morphology, leading to a decrease in thermal shock resistance due to the weak bridging mechanism [20,24] at high temperatures. Al2 O3 -MgO-CaO-BaO refractories as steel ladle linings were prepared by reaction and sintering of powder mixtures. The effects of BaO addition on the phase composition, sintering behavior, and properties of this composite were discussed to understand the mechanisms of improving the properties of this system material and to achieve longer service life as steel ladle linings

Experimental Process

Densification and Phase

Microstructure

12 O19 possesses

Mechanical Properties

Conclusions