A novel approach to prepare high strength and high porosity reticulated porous ceramics by in-situ synthesis of mullite whiskers

Abstract

A novel fabrication method for reticulated porous ceramics (RPCs) with high strength and high porosity has been proposed based on polymeric replica method and in-situ synthesis of mullite whiskers. Through the FactSage theoretical prediction, the mullite was produced in A10, A15 and A20 coating slurries and the liquid phase viscosity was decreased with increasing sintering temperature and AlF3 content. The results show that as the AlF3 content in coating slurry increases, the amount of mullite phase increases and the internal pore structure of the struts in the RPCs changed from triangular to rounded. Adding appropriate AlF3 content in the coating slurry facilitated the growth of mullite whiskers, but excessive AlF3 content caused the formation of amorphous crystals. The method used here improved the compressive strength without significantly reducing the porosity. Compared to untreated specimens, the compressive strength and residual strength ratio of sample A15 were increased by 38.24% and 19.75%.