Effects of Cr2O3 Content on Microstructure and Mechanical Properties of Al2O3 Matrix Composites

Kunkun Cui,Jie Wang,Shahid Hussain,Yingyi Zhang,Xu Zhang,Tao Fu,Tahani Saad Algarni,Shafaqat Ali

doi:10.3390/coatings11020234

Abstract

Al2O3-Cr2O3 refractories are completely substitution solid solutions and can effectively resist slag erosion when used as an industrial furnace lining. In order to provide suitable chromium corundum refractory with excellent slag resistance and mechanical properties for smelting reduction ironmaking, Al2O3-Cr2O3 samples with different mass percentages (0, 10, 20, 30, 40 wt.%) of Cr2O3 were prepared by a normal pressure sintering process to study its sintering properties, mechanical properties, thermal shock resistance, and microstructure. The results of densification behavior showed that the introduction of Cr2O3 deteriorates the compactness, the relative density and volume shrinkage rate of the composite material decrease with the increase of the Cr2O3 content, and the apparent porosity increases accordingly. In terms of mechanical properties, the hardness, compressive strength, and flexural strength of Al2O3-Cr2O3 material decrease gradually with the increase of Cr2O3. After 10 and 20 thermal shock cycles, the flexural strengths of the samples all decreased. With the increase of Cr2O3 in these samples, the loss rate of flexural strength gradually increased. Considering the slag resistance and mechanical properties of the composite material, the Al2O3-Cr2O3 composite refractory with Cr2O3 content of 20–30% can meet the requirements of smelting reduction iron making kiln lining.

Highlights

The smelting reduction ironmaking process has a wide adaptability for raw material sources, which can avoid the use of coke
FsizriengofsthhreinAkla2gOe3i-sCtrh2eO3cosmolbidined efsfeoclut otifosninptehrainseg iasnadbtohuetrm2 atol t1ra0nμsfmor,masatsihono/wrenacintioFnig[u13r]e. 3Ahc–ekr.taTinheamatooumnitcopf evrocleunmtaegsehraindkage weight percentage of Cr gradually increase with the increasing of Cr2O3 content, which is consistent with the XRD analysis results
The trend of apparent por (AP) can be observed from the figure that increased from 3.8% of the original sample A to 8.2% of the sample Al2O3-40 wt.% Cr2O3 (A-40C), which indicates that the addition of Cr2O3 will gradually increase AP

Summary

Introduction

The smelting reduction ironmaking process has a wide adaptability for raw material sources, which can avoid the use of coke. The lining materials used in smelting reduction ironmaking reaction furnace mainly include Al2O3-C, MgO-C, MgO-Cr2O3, and Al2O3-Cr2O3 refractories [5,6,7,8]. Some people suggest that the slag resistance of Al2O3-Cr2O3 bricks in the smelting reduction ironmaking furnace can be improved when the content of Cr2O3 is increased on the basis of the original Al2O3-Cr2O3 bricks. Li et al [22] reported the slag resistance to smelting reduction of Al2O3-Cr2O3 refractories with different Cr2O3 contents. There are few studies on the mechanical properties, thermal shock resistance, and microstructure of the composites due to the addition of Cr2O3. The effects of Cr2O3 content on the porosity, hardness, linear shrinkage, density, flexural strength, compressive strength, and thermal shock resistance of composite refractories have been widely discussed. Some reasonable suggestions on the selection of lining refractories in smelting reduction ironmaking are presented

Materials Preparation

Characterization

Consolidation Behaviour

Findings

Conclusions