Mechanical Properties of Man-Made Mineral glass fibres

In nature basaltic volcanic glass fibres are know from Hawaii as Pele's hair, formed by droplets of lava thrown into the air during volcanic eruption. The concept of glass fibre formation by an air stream dragging fibres from drops of melt is copied in industry to form basaltic glass wool fibres; man-made mineral glass fibres. The basaltic melt is prevented from crystallizing due to the high cooling rate, forming the mineral glass wool fibres.

Basaltic mineral wool fibres are of high interest in industry due to their good chemical durability and excellent heat and sound insulation properties and hence they are used for insulation products. In spite of those advantages, man made mineral wool fibres still show a certain degree of brittleness, which limits the further improvement of man made mineral wool fibres for both transportation and application. Therefore, a reduction in the brittleness of man made mineral wool fibres, and an improvement of the mechanical performances of man made mineral wool fibres are an evitable task for us. To do so, it is important to look into the fracture behaviour and its connection to the mechanical strength.

In order to improve the understanding of the information gained from the mechanical tests, fracture characteristics of individual glass fibres are imaged by scanning electron microscopy. The fracture surfaces showed to fall in three groups; 1) surfaces including fracture mirror, mist and hackle, 2) bend fracture surfaces and 3) surfaces including pores. The first group is by far the most common, the second group illustrate that the failure did not appear in uniaxial tensile stress and the last group is very small. By use of the characteristics of the fracture surfaces within the first group show the strongest fibres to produce the smallest fracture mirror to fibre cross section ratio.