Crystallization of Glass Fibers for Fireproof Insulation
Date
2017-05
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Abstract
Mineral wool is a truly engineered material in that at room temperatures it is a glass, but when heated above the crystallization temperature, it crystallizes. The main application of mineral wool is fireproof insulation, although it also provides thermal and acoustic insulation. When traditional fiberglass insulation is subjected to high temperatures, it slumps or melts. However, when mineral wool insulation is exposed to these elevated temperatures, it crystallizes and is able to maintain its structural integrity. The main focus of this work was to study the nucleation and crystallization behavior of this glass-ceramic. The hypothesis of the study is that iron, in particular iron (II) promotes crystallization. Several methods of characterization were carried out to study the crystallization of this material including Differential Scanning Calorimetry (DSC), High Temperature X-ray Diffraction (HTXRD), High Temperature Scanning Electron Microscopy (HTSEM), SEM, and X-ray Photoelectric Spectroscopy (XPS). Four of the six samples provided by Owens Corning Inc. formed the phase clinopyroxne [Ca(Mg, Al)((Si, Al)O6)]. Akermanite [Ca2(Mg, Fe, Al)(Fe, Al)Si2O7] was the main phase of the other two samples. Akermanite is classified under the sorosilicates, which form silicon tetrahedral pairs, while clinopyroxne is classified under the inosilicates, which form chains of silicon tetrahedra. Samples with a lower former to modifier ratio formed a sorosilicate because it had more modifier and modifiers tend to break up the glass network. Samples with a higher former to modifier ratio contained fewer modifiers, so they formed long chains of silicon tetrahedra (inosilicates). The nature of nucleation and growth was as expected, as samples with lower iron content contained larger crystals, presumably from fewer nuclei. This trend was observed across an iron content ranging from 2.65 wt% to 17.32 wt%. This research will enable optimizations of their raw materials to provide cost and energy savings in manufacturing.
Description
Thesis completed in partial fulfillment of the requirements for the Alfred University Honors Program.
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Honors thesis, Materials science, Glass-ceramics, Fireproof insulation