Environmental Fatigue of Silicate Glasses in Humid Conditions

Abstract

Failure strains of commercial silica, soda-lime-silicate, and E-glass fibers were measured using two-point bending in room temperature humid air. Humidity dependence and dynamic fatigue behavior were studied, and the fatigue reaction orders in terms of humidity were determined. In the humidity range tested (~0.1% to~100%), the dynamic fatigue parameters for silica and E-glass are found to be greater in lower humidity (~0.1% to~10%), whereas the fatigue parameter for soda-lime-silicate is independent of humidity. The humidity dependence of failure strains for all three glasses was more pronounced in high humidity (~10% to~100%) than in low humidity (~0.1% to~10%), indicating that the reaction order decreases with decreasing humidity. These observations were correlated with the different structures of the glasses and their corresponding fatigue mechanisms.

Effects of iron concentration and redox states on failure of boron-free E-glass fibres under applied stress in different conditions

“…The effect of ageing on the failure characteristics of glass fibres with different total iron concentrations and iron redox ratios was studied by using the two-point bending (TPB) technique to determine the maximum strain on the fibre at failure. The test procedure using the two-point fibre bending apparatus (TNL Tool and Technology, LLC, Parnell, IA) has been described in detail elsewhere [9,10]. For aged fibres, the TPB tests were performed under two conditions, namely, in ambient air at room temperature (22 ± 1 • C) at a RH of 50 ± 1% ('wet') and in liquid nitrogen at −196 • C ('dry').…”

Effects of acid leaching treatment of soda‐lime silicate glass on crack initiation and fracture

“…These loads may be much lower than the fracture strength of the material in the inert (water‐free) environment. The contribution of sub‐critical crack growth to fracture becomes large when the load is applied slowly in a humid environment 3,14‐16 . At a slower loading rate, more time is allowed for the corrosive effects of water to take place, resulting in the reduction of the measured fracture strength 14,15 …”