Three-dimensional porous silica ceramics with tailored uniform pores: Prepared by inactive spheres

Porous silica ceramics with uniform and fully interconnected pores in three dimensions are fabricated via sintering of randomly dense packed SiO2 spheres. The pores which origin from the space existed between stacked spheres are well reserved and the necks between spheres are formed during heat treatment. Due to the inactive surface of raw spheres, the uneven shrinkage is well restrained and the interconnected uniform pores are obtained. The pore size has linear relationship with sphere size as equivalent to D50 = 0.320 × d50 − 1.6. The neck strength can be enhanced by increasing sintering temperature in the range of 1090–1230 °C with negligible effect on pore structures. The permeable performance shows that the synthesized porous ceramic with D50 of 8.13 μm has an enhanced nitrogen permeance of about 4.4 × 106 L/(m2 h) under 150 KPa and its rejection coefficient of oil\water mixtures is up to 99% meanwhile the flux can reach 3.0 × 105 L/(m2 h).