Synthesis of Monolithic Potassium Geopolymer Ceramics Assisted by Molten Salt

Potassium geopolymer (KGP) ceramics are synthesized by the molten salt method. Metakaolin changes to a potassium geopolymer through a reaction with potassium silicate at 80 °C/24 h. Potassium geopolymer, with a silicon to aluminum (Si/Al) molar ratio of 2, turns into a leucite ceramic in molten potassium salt (KCl) at 900 °C/6 h. X-Ray Diffraction analysis of the KGP treated by molten KCl salt shows the amorphous phase change to leucite crystal phase. A scanning electron microscope image of sintered KGP proves that the grain size of the leucite crystal decreases with soaking time. Compared with solid state sintering, liquid molten salt sintering KGP can be more easily formed into dense ceramics at lower temperatures.