Abstract
A bi-modal porous ceramics with cylindrical pores and communicated pores were fabricated through unidirectional solidification of water slurry containing CO_2 gas. The cylindrical pores were formed during the unidirectional solidification under reduced pressure and a composite of ice and ceramics powder was obtained. Since the composite was formed by segregation of ice during the solidification, a communicated structure of ice was obtained. The ice was removed by vacuum freeze drying method. The porous bulk with cylindrical pores and communicated pores was sintered at 1250℃ for 5 hours. The porosity and pore size was well controlled by the pressure during the solidification and sintering temperature and time.
