Effect of particle size on pore three-dimensional characteristics of SiCp preforms by X-ray micro-computed tomography

Silicon-carbide particle (SiCp) preforms with particle sizes of 20, 50, 100 and 150 μm were prepared by compression mold forming and heat treatment. A high resolution (~ 1.0 μm) three-dimensional (3D) X-ray micro-computed tomography (X-ray μ-CT) combined with 3D pore-network models were used to study the effect of particle size on 3D characteristics and spatial structures of pores in the preforms. The results demonstrated that as the particle size increased, the gap expansion caused by burning of starch reduced. When the particle size increased from 20 to 100 μm, the average areal porosity, homogeneity of pore distribution, connectivity, the numbers of small pores and throats, and average pore coordination number decreased; the average effective sizes of pores and throats increased. When the particle size further increased to 150 μm, the large gaps were filled by small particles resulted from the broken coarse particles, which decreased the homogeneity and connectivity of pores. As a result, the pore-network analysis shows that the numbers of small pores and throats and average pore coordination number increased.