Fabrication of double-decker zircon aggregates by granulation and influence of TiO2 on the sintering process

In this study, four zircon granules are prepared by using granulation method and using TiO2 and sodium carboxymethyl cellulose (CMC) as a sintering additive and binder, respectively. Then, the effects of TiO2 addition on phase composition, pore size distribution and sintering process are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results reveal that only a small portion of zircon is decomposed into ZrO2 and SiO2 after sintered at 1250 degrees C, however, the zircon granules consist of zircon, ZrTiO4 and mullite after sintering at 1550 degrees C. In general, the addition of TiO2 accelerated the sintering process, promoted the migration rate of grains and transformed the apparent pores into closed pores, resulting in decreased pore size and enhanced compressive strength. The zircon granule, with 2.0 wt% TiO2, rendered an optimal apparent porosity of 24.0%, a high closed porosity of 8.35%, a high cylinder compressive strength retention rate of 44.9% and a relatively homogeneous pore size distribution after sintering at 1550 degrees C.