Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion

Abstract

Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to water and humid environments for decades, with a typical design lifetime being around 25 years or more. During this lifetime, these materials are affected by various temperatures, acidity levels, and mechanical loads. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was able to explain the long-term dissolution of R-glass fibres, considering the influence of the pH, temperature, and stress corrosion. The effects of these environmental conditions on the dissolution rate constants and activation energies of dissolution were obtained. Experimentally, dissolution was measured using High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). For stress corrosion, a custom rig was designed and used. The temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. In comparison with neutral conditions, basic and acidic aqueous environments showed an increase in the dissolution rates, affecting the lifetime of glass fibres negatively. External loads also increased glass dissolution rates due to stress corrosion. The model was able to capture all of these effects.

Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics

“…Linking the strength degradation results to the chemical dissolution of glass gives a possible quantitative link to the concept that the crack growth must somehow be related to a corrosion process. The fact that the experimental data can be well modeled by the dissolution constants K I 0 and K II 0 , representing the two dissolution phases, shows that crack growth also is influenced by the two phases of dissolution observed for fiber bundles [16] and also other types of glass [15]. We attempted to fit the experimental data with only one of the K 0 factors, but this did not work.…”

“…The authors measured a wide set of dissolution constants on glass fiber bundles in water at different temperatures and pH values [15]. The constants for phase 1 and 2 are listed in Table 4.…”

“…The authors of this paper studied the dissolution of glass fibers in distilled water (large "infinite" amount) for sized and unsized fibers. Regarding both cases, the dissolution could be well described with zero-order kinetics [14][15][16].…”

“…Afterwards, a steady state (Phase II) with a kinetic constant of K II 0 was observed. The dissolution rate of sized fibers was by factor ξ sizing = 0.165 s lower compared to desized fibers [14,15]. The results are summarized in Table 2.…”

“…Table 2. Dissolution constants for R-glass fiber bundles at 60 • C, after [15,16]. Modifying Equation 11for two dissolution constants, the strength loss with conditioning time is obtained:σ…”