Porous SiC-mullite ceramics with high flexural strength and gas permeability prepared from photovoltaic silicon waste

In this paper, porous SiC-mullite ceramics (PSMCs) with high flexural strength and gas permeability were prepared with various mass fractions of MoO3 and Al2O3. Higher performance was achieved at low sintering temperatures and the problem of large amounts of cristobalite phase in the PSMCs was solved. The results show that 4 wt% MoO3 is optimal for the growth of mullite rods at a sintering temperature of 850 degrees C. Porosity was effectively controlled by the formation of interlocking structure and mechanical strength was not obviously affected. Therefore, the optimal content of Al2O3 was 25 wt% in samples prepared at 850-1200 degrees C, as the flexural strength was generally higher than that in samples with other Al2O3 contents. The highest flexural strength of 66.02 MPa was achieved at an open porosity of 45.4%, gas permeability of 2.32 x 10(-13) m(2), and permeance of 4.62 x 10(-5) mol m(-2) s(-1) Pa-1 in samples sintered at 1000 degrees C. This work is of significance for the industrial preparation of PSMCs from photovoltaic silicon waste.