A novel and precise method to determine the upper limit of crystallization temperature of basalt melts for the production of continuous basalt fibers

The upper limit of crystallization temperature (Tc) of basalt melt is crucial for the production of continuous basalt fibers (CBFs). However, the precisely measuring Tc for basalt systems has been a challenging and time-consuming task. As a result, there is often a mismatch between the fiber-drawing temperature (Td) and the Tc of basalt melt during CBF production, which hinders the improvement of the mechanical properties and leads to the fiber fracture. To address these limitations, a new approach has been proposed to determine Tc by analyzing the inflection point of the viscosity-temperature curve, This is achieved by fitting an exponential function (y = y0 + A*exp(R0*x)). The results of this viscosity fitting technique were compared to the microstructure and morphology of basalt melts quenched at different temperatures, which were assessed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The findings indicate that the results from XRD and micro-observations are in agreement with the viscosity fitting method. Furthermore, the variations of Tc and Td in binary basalt systems were quantified, and it was revealed that their behavior follows the linear superposition principle based on the mass percentage Wi (i=1, 2) of the two end members. Empirical formulas have been developed to describe this relationship, which are given as Tc = W1×Tc1 + W2×T c1 and Td = W1×Td1 + W2×Td2. These findings not only contribute to the precise measurement of Tc but also provide new insights for modeling the prediction formula of Tc for binary basalt systems.