Effect of different foam stabilizers on the setting behavior and pore characteristics of CAC-bonded Al2O3 foamed ceramics

Calcium aluminate cement (CAC) was used in this work as a novel binder of the foam slurries to prepare Al2O3 foamed ceramics. The different foam stabilizers employed in the slurries would not only impact the foam stability, but also affect the setting behavior of CAC-containing foam slurries, consequently influencing the pore size and the heat-insulating property of the Al2O3 foamed ceramics. In this paper, modified polyethoxylated silicone (MPS), sodium alginate (SA) and carboxymethyl cellulose (CMC) were selected respectively as the foam stabilizer. The effects of the different foam stabilizers on the setting behavior of foam slurries, and the dependence of the pore size and heat-insulating property of CAC-bonded foamed ceramics on the setting behavior of foam slurries were investigated. It is found that SA promotes the hydration of CAC in the foam slurries, while MPS and CMC postpone the hydration of CAC in the foam slurries; and the foamed ceramics with SA have better structural integrity, higher porosity, smaller average pore size and lower thermal conductivity than those with MPS or CMC.