Effect of Blowing-Agent Addition on the Structure and Properties of Magnesia Porous Material

Abstract

Magnesia porous material was slip casted from magnesite flotation tailings, fused magnesia, and additives of sodium hexametaphosphate, sodium citrate, and α-Al₂O₃ powder. The suspension of magnesia porous material was prepared with foaming sodium dodecyl sulfate (SDS) and foam-stabilizing dextrin. The cured material was dried and sintered. The effects of adding blowing agent on the properties of the suspension and the physical properties and microstructure of the sintered specimens were studied. The results showed that the tested suspension was a pseudoplastic fluid. The apparent porosity of sintered specimens increased whereas the thermal conductivity decreased as the blowing-agent content increased. The number and size of local agglomerates decreased. The pore size increased. The grain-size and pore-size distributions became more uniform.