Density Changes in Fused Silica

JSGT 1951 V35T206-T225

In continuation of previous work on the configuration changes of glass in the transformation range, the density changes occurring in fused silica at 1000–1500 have been studied. The equilibrium density curve has been determined and the time taken to reach equilibrium found for various temperatures. The coefficient of expansion at temperatures below 1000° has been found to alter when the configuration changes; the density changes measured at room temperature are corrected for change of expansion in order to give the changes of density at the temperatures of heat treatment. The equilibrium density of fused silica is found to increase with increasing temperature, and this is attributed to the tendency of the open random network structure to break down at higher temperatures. The final section gives preliminary results on measurements of the volume of fused silica as a function of pressure in addition to time and temperature.

R. W. Douglas & J. O. Isard