Effect of ZrO2 on crystallization behavior of lithium aluminosilicate glass-ceramic powders by polyacrylamide gel method

A novel method based on polyacrylamide gel process was used to prepare Li-2 O-Al-2 O-3-SiO2 (LAS) glassceramic powders. The effects of ZrO2 addition on the crystallization and phase transformation process in LAS system were investigated by using differential thermal analysis (DTA), X-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). The activation energy decreases from 304.6 to 248.9 kJ/mol and the frequency factor decreases from 2.49 X 10(11) to 5.56 X 10(8) min(-1) as ZrO2 content changes from 0 to 4.0% (mass fraction). During calcination from 800 to 1 200 degrees C, hexagonal beta-quartz solid-solution first crystallizes and then gradually transforms into tetragonal beta-spodumenei solid-solution with increasing temperature. The stability of beta-quartz solidsolution increases with more ZrO2 additions and a minor crystalline phase, tetragonal zirconia, also appears.