Effect of CaO on Thermal Expansion Properties of Li2O-Al2O3-SiO2 Glass-Ceramics
In recent years,the price of lithium ore,one of the main raw materials of Li2O-Al2O3-SiO2(LAS)glass-ceramics,continues to rise,so it has great significance to carry out research on lithium reduction of LAS glass-ceramics for the sustainable development of LAS glass-ceramics enter-prises.LAS-basic glass was prepared by melting method,and LAS glass-ceramics were obtained by annealing,nucleation and crystallization treatment.The effects of CaO on crystallization behavior and thermal expansion of LAS glass-ceramics were systematically studied.The results show that CaO can promote grain growth and crystallization.When CaO content increases from 0.3%to 0.8%,the grain size increases from 32.66 nm to 34.92 nm,and the crystals begin to increase when CaO content is more than 0.6%.The bond-breaking effect of Ca2+is not as strong as that of Li+when the amount of CaO is low,as a result,the high-temperature viscosity does not decrease.With the mass ratio of CaO and Li2O increases,the interaction of Li+and Ca2+leads to the looser structure of the glass network,thus increasing the coefficient of thermal expansion.The average thermal expansion coefficient of C0.3-C0.8 samples in the range of 25-600℃is less than 8×10-7/K,indicating that the glass-ceramic samples of this group of formulations has good thermal stability.
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