Effect of MgO/Al2O3 Ratio on Phase-separation and Crystallization of MgO-Al2O3-SiO2 Glass

Cordierite-based glass-ceramics with diverse MgO/Al2O3 ratios were prepared by high temperature melting met-hod. The impact of MgO/Al2O3 ratio on the phase separation and crystallization behavior of the MgO-Al2O3-SiO2 glass were investigated by means of differential thermal analyzer (DTA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicated that with the constant content of SiO2, the decrease of MgO/Al2O3 ratios leaded to the morphology change of phase separation droplets from worm-like shape to isolated sphere, and the gradual size reduce of phase separation droplets from 200-300 nm to 30-50 nm. The increase of crystallization peak temperature (Tp) from 997℃ to 1 105℃could be observed as the MgO/Al2O3 ratio decreased from 3 to 1, which made the crystallization become more difficult. When the MgO/Al2O3 ratio is 3, the MgO-Al2O3-SiO2 glass would produce a large amount of phase separation droplets after heat treatment at 950℃. After heat treatment at 1 050℃, substantial cordierite crystals were precipitated in phase separation droplets, which were preferentially precipitated in Mg-rich phase. Increasing MgO/Al2O3 ratio was highly beneficial to the phase separation and crystallization in MgO-Al2O3-SiO2 glass. Conversely, reducing the MgO/Al2O3 ratio would weaken the the ability of phase separation and crystallization of the glass. © 2018, Materials Review Magazine. All right reserved.