Expansion characteristics of some Li_2-BaO-AI_2O_3_SiO_2 glasses and glass-ceramics

摘要

The thermal expansion characteristics of some glasses and glass-ceramics within the system LiAlSi_2O_6~BaAl_2Si_2O_8 are described. The expansion coefficient of glass decreases with the increase of BaAl_2Si_2O_8 content, while both the transformation (T_g) and softening (T_s) temperatures increased. The thermal expansion coefficients of glass-ceramics exhibited a wide range depending upon the type and relative proportions of the crystalline phases present. The alpha -values of the studied glass ranged from 58.34 to 75.03 X 10~(-7)/ deg C in the 20-300 deg C temperature range and those of the crystalline products ranged from 3 to 80 X 10~(-7)/ deg C in the same temperature range. The break in the expansion curves of the crystalline samples at about 300 deg C defined the reversible transformation temperature of the orthorhombic <=> hexagonal-celsian.