Figure 5.

Microstructure of porous ceramics produced via the reaction method: (A) porous SiC ceramics produced using 67% polysiloxane, 13% phenol resin, 3% Y₂O₃, 2% Al₂O₃, and 15% expandable microspheres (461DU40). The green compact was expanded at 138 °C and subsequently cross-linked at 180 °C, pyrolyzed at 1200 °C for 1 h and further heat-treated at 1650 °C for 2 h in argon; (B) porous cordierite obtained using 23.5% polysiloxane, 32.7% talc, 26.3% Al₂O₃, 2.5% kaolin, and 15% expandable microspheres. The green compact was expanded at 138 °C and subsequently cross-linked at 180 °C in air. The cross-linked compacts were heat-treated at 1350 °C for 4 h in air.