Study on porosity of ceramic SiC using small angle neutron scattering

The mechanical properties of functional heat-resistant ceramics SiC are significantly influenced by the concentration and dimensions of pores. Small angle neutron scattering measurements for 3 SiC samples with different densities are performed on C1-2 SANS instrument of the University of Tokyo. Two groups of the neutron data are obtained using 8 and 16 m of secondary flight path, 1 and 0.7 nm of neutron wave lengths, respectively. After deduction of background measurement and transmission correction, both neutron data are linked up with each other. The patterns of neutron data of 3 samples with Q range from 0.028 approx. 0.5 nm-1 are almost with axial symmetry, showing that the shape of pores is almost spherical. Using Mellin transform, size distributions of pores in 3 samples are obtained. The average size (approx. 19 nm) of pores for hot-pressed SiC sample with higher density is smaller than the others (approx. 21 nm). It seems to be the reason why the density of hot-pressed SiC sample is higher than not hot-pressed sample.