China's Refractories

Abstract: SiC porous ceramics were prepared at 1 400 ℃ for 4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH₄HCO₃ as the pore-forming agent. Effects of NH₄HCO₃ additions (0, 20%, 30%, 40%, by mass) on the phase composition, microstructure, sintering properties, cold compressive strength and thermal shock resistance of as-prepared SiC porous ceramics were investigated. The results show that: (1) addition of NH₄HCO₃ remarkably influences the apparent porosity and cold compressive strength of specimens. The apparent porosity achieves its maximum value (63.40%) when 40% NH₄HCO₃ is added, while the minimum cold compressive strength is 4.77 MPa; (2) the specimen with 40% NH₄HCO₃ has the best thermal shock resistance. The thermal cycling times between 1 000 ℃ to room temperature reach 62; (3) the addition of NH₄HCO₃ does not remarkably affect the phase composition of the specimens; (4) the specimens include a large number of SiC particles and a small amount of SiC whiskers.