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

[摘要] Hydrolysis resistance of boron-free E-glass fibre with different total iron oxide (Fe$_2$O$_3$) concentrations, iron redox index and durations of fibre ageing up to 180 days at 50$^{\circ}$C with 50% relative humidity (RH) was studied. The effect ofageing on the fibre failure measured in two different test environments was examined by using two-point bending method.Based on the differences in failure strains of the fibres obtained from the two conditions as a function of ageing time, theGriffith theory of solid fracture was applied to estimate glass surface energy difference in ageing conditions. The resultsshowed that stress-assisted hydrolysis, when the fibres were under stress, could lead to about 5.18 times reduction in surfaceenergy to account for 2.30 times reduction in fibre failure strain when tested in 50% RH at room temperature.Our study showedthat the boron-free E-glass aged up to 180 days only deteriorated within 13%, independent of total Fe$_2$O$_3$ concentration andFeO/Fe$_2$O$_3$ total ratio, and stress-assisted hydrolysis played a key role during sample testing. Dynamic fatigue of the aged E-glass fibres was also investigated, showing little influence of total Fe$_2$O$_3$ concentration and FeO/Fe$_2$O$_3$ total ratio on fibre stress; corrosion susceptibility was observed.

[学科分类] 材料工程

[关键词] Iron oxide;ageing;failure strain;surface energy;hydrolysis;glass fibre.