Improvement in the strength of reticulated porous ceramics by vacuum degassing

SiC reticulated porous ceramics (RPCs) were fabricated from ceramic slurries by the replication process with polyurethane sponges as the templates. Vacuum degassing was adopted to remove air bubbles in the slurry. Effect of degassing on the rheological behavior of the slurry and the properties of RPCs was investigated. The slurry showed a slight increase in viscosity after degassing, which improved the loading of the slurry on the sponge. The large defects in the struts were significantly reduced by degassing, which was confirmed by scanning electron microscopy (SEM) observation and Hg porosimetry. Flexural strength of RPCs increases from 2.34 to 3.18 MPa after degassing, The results were discussed in terms of an available theoretical model on the mechanical behavior of open cell ceramics. (C) 2001 Elsevier Science B.V. All rights reserved.