High-temperature properties of mineral wool.

Thermal stability and thereby fire safety is an essential property of fibrous insulating materials for buildings. At the same time the viscosity is an important manufacturing property that may impair the thermal stability. This project aims at investigating the thermal stability of some mineral wool fibres by studying their crystallization behaviour as a function of temperature, time and composition. Stone wool fibres are compared to hybrid fibres with viscosity in-between stone wool fibres and glass fibres. Of particular interest is the role of the Fe3+/Fe2+ ratio on the crystallization behaviour. Figure 1. Isothermal X-ray powder diffraction patterns collected at beamline 711, MAXLAB, Lund, using a Huber G670 Guinier camera. The sample was contained in a 0.5 mm quartz capillary, data were accumulated for 5 min per pattern at T = 1100 K and lambda = 1.2724 Å. Preliminary results show that the stone wool fibres have a low Fe3+/Fe2+ ratio and crystallize as diopside and periclase. The hybrid fibres crystallize as diopside, nepheline, and periclase. Stone wool fibres with higher Fe3+/Fe2+ ratio crystallize as diopside, periclase, cristobalite and an unknown phase indexed as cubic with a = 3.94 Å. The identified phases were confirmed by Rietveld refinements. The impact of the crystallization behaviour on the thermal stability will be discussed.