Effect of water content in phosphate glasses on slow crack growth rate

Abstract

Slow crack growth in phosphate glasses with different water contents was measured at 225°C and room temperature under different water vapor pressures using double-cleavage-drilled compression (DCDC) samples. Higher water vapor pressure caused a faster crack growth velocity at a constant temperature for all samples. At 225°C under a constant water vapor pressure, glasses with higher water content exhibited greater crack velocity. However, at room temperature under a constant water vapor pressure, samples with lower water content exhibited a higher crack velocity. This room temperature behavior is probably caused by water uptake by the sample during the crack growth measurement. In support of this hypothesis, weight gain was observed when the glasses were exposed to humid atmosphere at room temperature, with the samples having lower water content exhibiting the greater weight gain.