Glass ceramics of high hardness and fracture toughness developed from steel fly ash

Abstract

A study has been carried out on the feasibility of using a high iron content fly ash, generated during steel making, as a raw material for glass ceramic production. The fly ash was mixed in different proportions with soda–lime glass cullet and sand. The devitrification of the parent glasses produced from the different mixtures was investigated using differential thermal analysis, X-ray diffraction and scanning electron microscopy. The mechanical properties of the glass-ceramics were assessed by hardness and indentation fracture toughness measurements. A glass ceramic with composition of 60 wt-% fly ash, 25 wt-% sand and 15 wt-% glass cullet and containing magnetite in a marked dendritic morphology exhibited the best combination of properties, namely, hardness 7·9 GPa and fracture toughness 3·75 MPam^0·5. These new hard glass-ceramics are proposed for wear resistant tiles and paving for heavy duty industrial floors. In powder form, the glass ceramics are candidate materials for blasting and abrasion applications.