Improvement in the strength of reticulated porous ceramics by vacuum degassing

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