Effects of Zirconia and Alumina on the Properties of Clay Bonded SiC Refractories

摘要

In this research, the effects of Alumina and Zirconia additives on the properties of clay bonded SiC refractories were analyzed. Different formulations were made with 5 to 30% clay, 0 to 10% Zirconia and 0 to 15% Alumina, along with some binders. The samples were sintered at different temperatures form 1400 ℃ up to 1600℃ in different atmospheres. Then, physical and mechanical properties at low and high temperatures were measured. The microstructural and phase analysis as well as DTA were conducted in the samples. The results indicate that the density of the first series of samples (Zirconia containing samples) is increased with clay and Zirconia contents. Accordingly, the CCS and MOR of the sample change at the same direction. The effect of Zirconia on MOR of the samples was not significant. The thermal conductivity of the sample with 95% SiC and 5% clay was about 30 w/m.k. Also, the results indicate that the RUL of samples was lowered by increasing the clay content and was increased by adding the Zirconia. The results showed that adding of Alumina in the second series of samples (Alumina containing samples) increased the amount of Mullite. Blistering effect was enhanced by increase of clay and Alumina content in SiC bodies. Mullite phase was increased by addition of Alumina till 15% in SiC bodies under reduced atmosphere. The overall results indicate the formation of Mullite, glassy phase, Quarts and the mixture of Monoclinic and Tetragonal phase in the system.