Preparation of Calcium Hexaluminate using Al_2O_3 and White Beach Sand from Western Australia

摘要

Calcium hexaluminate (CA_6) is valued as a new high-temperature insulation materials because of its high stability, high melting point and low thermal conductivity properties. In this paper, chemical analysis and XRD were used to investigate the composition of the white beach sand mineral from Perth coast of Western Australia, which was consisted of carbonate. White beach sand as calcium source and industrial alumina as aluminum source respectively were used to synthesize CA_6 at 1550 °C-1650 °C for 3 h. Effects of different amounts of alumina and sintering temperature on synthesis of calcium hexaluminate were studied. The results showed that synthetic CA_6 was shaped in platelet crystalline. The main phase of the samples with decreasing or increasing 5%, 10% and 15% alumina around theoretical ratio were CA_6. The porosity of the samples obtained was about 53%. The bending strength of sample of theoretical ratio was up to 7.73 MPa. Sintering temperature from 1500 °C to 1650 °C was not conductive to the improvement of apparent porosity of CA_6 materials.