Effect of dissolved water on the internal friction of glass

The two internal friction peaks in (1-X) Na₂P₂O₆· X Al₂O₃ glasses showed a pronounced dependence on the water content. With increasing water content, the alkali peak became 10-20% smaller and a slight increase in the activation energy was indicated. Similarly, the second peak became 2-4 times larger and shifted to lower temperatures. From the close correlation between the magnitude of the second peak and the water content, the mechanism for this peak was concluded to consist of the cooperative movement of a sodium ion and a neighboring proton. Comparison of aluminophosphate and alkali silicate glasses showed that the internal friction peaks have a similar dependence upon the water content in both types of glasses. It is concluded that the water content of a glass should be closely controlled when the effect of other compositional changes on the internal friction is being studied.