Preparation of porous mullite–corundum ceramics with controlled pore size using bioactive yeast as pore-forming agent

• Porous mullite–corundum ceramic with controlled pore size was prepared.
• Well distributed bioactive yeast cell was chosen as pore-forming agent.
• Apparent porosity was about 55% when mass ratio of yeast to ceramic powders is 1:2.
• The porous ceramic has narrow pore size distribution and regular pore structure.

In this letter, porous mullite–corundum ceramics with controlled pore size and microstructure were prepared by the reaction-bonding method using boehmite and silicon dioxide micro-powders as raw materials, bioactive yeast cell as a pore-forming agent, respectively. The effects of the mass ratio of bioactive yeast cell to ceramic powders and calcination temperature on the phase development, microstructure and pore size distribution of the products were investigated. Results show that regular oval-like pores can be formed when yeast cell was added. The main pore size distribution is in the range from 0.5 to 3 μm, and the porosity of the porous mullite–corundum ceramic is about 55% when the mass ratio of yeast to ceramic powders is 1:2. The narrower pore size distribution and regular microstructure of the pores are beneficial to improve the filtration accuracy and strength of the porous ceramics.