The Si2p spectra of the prepared filters at various sintering temperatures are shown in Fig.7. The spectra were background corrected based on the C–C bonding of the C1s peak(binding energy:284.6eV) and the peak of Si2p could be peak-fitted with Si–Si (99.2eV) Si–O (101.7eV or 101.8eV) Si–Ox(xo2) (102.7eV) and Si–O2 (103.4eV or 103.6eV). As shown in the figure, Si–Si bonding structure was not observed in the filter sintered at 1350 C and 1400 C; however,it appeared at sintering temperatures higher than 1450 C. In sufficient sintering temperature which was lower than the eutectic point, caused non-homogeneous bonding among mullite, zirconia,and calciumcarbonate powders