Tuning pore structure of corrosion resistant solid-state-sintered SiC porous ceramics by particle size distribution and phase transformation

Abstract

Aggressive process environment like hot corrosive water treatment caused corrosion in ceramic membrane and strength degradation of the membrane support, resulting in the invalidation of membrane filtration. Therefore, new SiC membrane support based on its intrinsic corrosion resistance was prepared by the combination of bi-modal particle size distribution and solid-state-sintering with 1–3wt.% of B4C additive at 2150°C and 2200°C. By tuning the contents of coarse and fine powder and without introducing any pore-creating agent, the porosity of SiC supports varied in the range of 36–39%, which was suitable for the membrane filtration. The phase transformation of 6H–SiC to 4H–SiC induced by the addition of B4C at 2200°C, accompanied by the formation of large plate-like grains, caused the pore size increased from 11.8μm to 20.9μm. The corrosion resistance of solid-state-sintered SiC supports was evaluated by exposing in 90°C 20wt.% H2SO4 and NaOH solutions for 200h. The high residual flexural strength (≥92.5%) and unchanged microstructure of the solid-state-sintered SiC supports after corrosion demonstrated that the supports exhibited excellent corrosion resistance and would be promising candidates to substitute the traditional ceramic supports.