研究了成分(摩尔%)为75SiO_2,12. 5CaO,12. 5Na_2O 和80SiO_2,10CaO,10Na_2O 的玻璃在650℃或(及)760℃热处理不同时间的分相行为。描述了不稳分解、成核生长两种分相及成分在不混溶区边界附近的玻璃形貌。在成核生长分相的区域发现一种典型的受高粘度阻滞的奥氏成熟(Ostwald-type Ripening)现象。在不混溶区边界附近因高温挥发或表面析晶发生的成分微量波动足以使分相行为显著改变。用超声波测定了弹性模量、剪切模量、压缩模量及泊松比。用三点及四点法测定了玻璃抗弯强度;还测定了 Tg 和密度。不稳分解和成核生长两种分相机理对性质的影响不同。此外,性质还与分相程度密切相关。

Phase Separation of Glasses in the Na_2O-CaO-SiO_2 System and their Mechanical Properties Xie Yushen R.BrücknerPhase separation of glasses of compositions (mole%)12. 5 Na_2O;12. 5 CaO; 75 SiO_2 and 10 Na_2O;10 CaO;80 SiO_2 was studied after heat treatments for different times at 650℃,760℃ or both.The morphology in the spinodal and binodal regions as well as at the boundary of the phase separation region is described.In the binodal region a typical Ostwald ripening was found which was much restricted by the viscosity.Towards the bounoaries of the immiscibi- lity range great changes in phase reparation are produced by relatively small changes in chemical composition caused by crystallization or the evaporation of components at higk temperature. Elastic,shear and compression meduli as well as Poisson's ratio were measured by ultra sonic impulse and the bendling strength of the glasses dete- rmined by three and four point loading;the transformation temperature Tg and density were also measured.Metastable binodal phase separation gave re- suits different from those for spinodal separation.The properties also depend on the extent and texture of phase separation in a characteristic way.