Fiber spinnability of glass melts

Abstract

Fiber spinnability is the ability of a glass‐forming melt to be steadily stretched and spun into defect‐free fiber filaments. However, its quantification has not been well established owing to many controlling factors such as melt fragility, melt strength, surface tension, liquidus temperature, liquidus viscosity, and crystallization. To understand and quantify the fiber spinnability of a glass melt, we consider two key aspects: fiberizing viscosity window and melt stability. The fiberizing viscosity window is defined by the upper and lower viscosity limits. Fibers rupture above the upper viscosity limit, whereas a stable melt stream cannot form below the lower limit (ηlow). We introduce a simple parameter to quantify fiber spinnability, namely, Kfib=ηL/ηlow, where ηL is the viscosity at liquidus temperature (TL). A fiber can only form if Kfib>1. To quantify melt stability we propose the parameter of S=(TL‐TC)/(TL‐Tg), where TL and TC are the liquidus temperature, and the onset temperature of melt crystallization during cooling, respectively. Both parameters (Kfib and S) are important for a rational design of glass fiber compositions, and fiberizing process. We use two basalt melts as examples of this study to demonstrate the high sensitivity of fiber spinnability to a minor variation in chemical composition of melts.

Effect of Nozzle Diameter on Basalt Continuous Fiber Properties

“…The influence of the basalt and E-glass melt viscosity, cooling rate, structural heterogeneity, and technological defects on mechanical and thermal properties were studied in detail by Yue et al [13][14][15][16]. The authors suggest the existence of non-Newtonian extensional thinning flow in a fibrous stream [12]. This can indirectly confirm the fact that many experiments have shown that the melt flow rate through nozzles for E-glass exceeds the theoretical one by several times [17,25].…”

“…The second group can be conventionally attributed to the technological parameters [12]. The effect of technological parameters (winding speed, melt temperature, nozzle diameter, etc.)…”

Determining the liquidus viscosity of glass‐forming liquids through differential scanning calorimetry

“…2,3 A larger η L indicates a higher glass-forming ability. Hence, η L is a governing factor for glass fiberizing processes, 4 and it is important in the design of new industrial glass compositions. For example, recently a fiber spinnability index has been proposed to quantify the ability of a glass melt to be spun into fiber filament in terms of η L .…”

“…For example, recently a fiber spinnability index has been proposed to quantify the ability of a glass melt to be spun into fiber filament in terms of η L . 4 Liquidus viscosity is typically determined by direct viscosity measurements at T L . Viscosity measurements can be performed with various types of viscometers, 5 but several factors can make it difficult to apply viscometry in many cases, for example, melt volatilization, crystallization, limited sample availability.…”

Mixed alkaline‐earth effects on several mechanical and thermophysical properties of aluminate glasses and melts

“…By performing the atomic force microscope analysis on the Ca‐Mg mixed silicate glasses, Kjeldsen et al observed a direct link between the volume of plastic flow and the Vickers hardness ( H v ), suggesting that the mixed alkaline‐earth effect on H v originates primarily from the nonlinear compositional dependence of the ability of the mixed modifier glasses to resist plastic flow . The glass fiber spinnability is sensitive to variation in the Ca/Mg ratio for the aluminosilicate glasses . The “dynamic structural mismatch model” is useful in clarifying the structural origin of mixed alkaline‐earth effect regarding mechanical and rheological properties in silicate glasses .…”