WU Jianfeng, SANG Yu, XU Xiaohong, ZHOU Yang, DING Chunjiang, ZHOU Shixiang

(State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, Hubei, China)

Abstract: Corundum-mullite porous ceramics with large pore size and high closed pores were prepared, with α-Al₂O₃, quartz and Suzhou clay as the main raw materials. Polystyrene balls were used as the pore forming agent, Y₂O₃and Sm₂O₃ were employed as the auxiliary agents. The effects of Y₂O₃ and Sm₂O₃ on structure and properties of the corundum-mullite porous ceramics were studied, by using SEM, XRD and so on. The addition of Sm₂O₃ and Y₂O₃ reduced open porosity and increased closed porosity of the samples, respectively. The samples with both Sm₂O₃ and Y₂O₃ possessed the lowest porosity and the highest closed porosity, which were 20.03% and 52.80%, respectively. According to XRD results, the major phases in all the samples were corundum and mullite. Stereomicroscope and SEM images revealed that the optimal samples were all evenly distributed with large and small pores. The presence of Sm₂O₃ and Y₂O₃ promoted the formation of liquid phase at high temperatures and inhibited the formation of mullite. The glassy phase filled the connecting pores and only tiny closed pores were formed independently, thus increasing the closed porosity of the samples.

Key words: porous ceramics; closed porosity; microstructure; rare earth oxides