To investigate these phenomena,we observed the morphological changes of the prepared ceramic filters at various
sintering temperatures and their grain size distributions with FE-SEM images(see Fig. 2). As shown in the figure, we can
see non-uniform powder distributions in the filters prepared at sintering temperatures of 1350 C and 1400 C, and the most
uniform is observed at 1450 C. However,a further increase in sintering temperature led to an increase in powder flow ability and over-firing, resulting in morphological changes in the filter media.In particular,the morphology of a ceramic filtersintered at 1550 C was drastically changed compared to others.The measured grain sizes were also different (52.31 μm for 1350 C, 53.55 μm for 1400 C, 53.52 μm for 1450 C,and 58.02 μm for 1500 C, respectively),even though it was
prepared with the same powder size.The increase in grain size may provide higher porosity in the filter media,as Sánchez
et al. demonstrated [23]. In particular,the grain size of a ceramic filter sintered at 1500 C was drastically increased compared to others,and this large grain size provided higher porosity than the filter sintered at 1450 C. We can clearly see
that internal morphology,pore characteristics,and grain size in the filter media strongly depend on sintering temperature.