The effect of sintering temperature on the structure and properties of calcium hexaluminate/anorthite ceramics

Y Tian,Y Qiu,C Gong,P Bai,Y Chai

doi:10.2298/sos1302141t

Y Tian, Y Qiu + Show 3 more

Open Access

https://doi.org/10.2298/sos1302141t

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Abstract

The calcium hexaluminate/anorthite composite are prepared by magnesia slag, kaolin and industrial alumina at different sintering temperature. The effect of sintering temperature on the structure and properties are investigated by X-ray powder diffraction and scanning electron microscopy. The results show that the calcium hexaluminate begins to form at 1300?C and continues to form in a large amount between 1400?C and 1500?C, however, there is a phase transitions form gehlenite to anorthite between 1300?C and 1400?C. CA6 grow preferentially along the basal plane direction. When the crystals touch each other, the CA6 crystals turn to grow up along the axial direction. The apparent porosity decreases and bulk density increases and the flexural strength increases with the rising of the sintering temperature.

Highlights

Since 21st century, the energy issue has become a problem we human have to face
Crystalline calcium hexaluminate (CaAl12O19, CA6) is a good candidate to satisfy the requirements in view of fabrication of insulation material due to its low thermal conductivity and good thermal stabilities
The samples, the CA, CA2 precursors [7] and CA6 are observed at 1300 oC,a small quantity of gehlenite (C2AS) and anorthite (CAS2) are observed

Summary

Introduction

Since 21st century, the energy issue has become a problem we human have to face. the development of new energy has made some progress, world demand for energy continues keeps growing, energy are still in short supply. Crystalline calcium hexaluminate (CaAl12O19, CA6) is a good candidate to satisfy the requirements in view of fabrication of insulation material due to its low thermal conductivity and good thermal stabilities. Hallstedt [1,2] have reported that calcium hexaluminate has a theoretical density of 3.38 g cm-3, melts at 1850 oC. It crystallized in hexagonal system, space group P63/mmc, and has magnetoplumbite structure [3,4]. The refractory materials with the main crystal phase of calcium hexaluminate and the minor crystal phases of anorthite will have a very good effect on heat insulation and have high service temperature. The effect of sintering temperature on the structure and properties were investigated

Experimental

XRD analyses

SEM analyses

Physical properties

Conclusion