Effect of dispersion viscosity on microstructure of cordierite foam prepared by thermo-foaming

The thermo-foaming method developed in recent years is considered to be an efficient technique for the preparation of highly porous foam ceramics; however, small foam cells that contain particles are often formed under certain conditions, which is a disadvantage that needs to be overcome. In this study, we used the thermo-foaming method to prepare cordierite foams and investigated the effect of dispersion viscosity on the microstructure of the foam at various foaming temperatures. The bubble-rupturing pathway during the foaming process was found to depend on the dispersion viscosity, which resulted in the formation of cordierite foams with remarkably different microstructures at different dispersion viscosities. The high dispersion viscosity at a foaming temperature of 130 degrees C resulted in an extremely low degree of foaming, which led to smaller cells in the cordierite foam that contained cordierite particles. However, the dispersion viscosity decreased as the foaming temperature was gradually increased; as a result, the degree of dispersion foaming improved and fewer smaller cells containing cordierite particles were formed.