1. Refractories
Refractories are materials (usually nonmetallic)
that maintain enough physical and chemical
identity to be used for structural purposes in the
high temperature environment encountered in
process industries
2. • Exposed to high temperatures
• Effects of other conditions
– Mechanical stress
– Thermal cycling & associated stress
– Erosion
– Corrosion by hot gas and molten materials e.g.
metals, slags or glasses
3. First Use of Refractories
• Stone age
• Value of stone substances in crude places of
fire for containing and reflecting heat
• Sandstone does not spall ( granite spall)
• Does not disintegrate ( Limestone
decomposes)
4. Uses of Refractories
• Although refractories are used in most, if not
all, of U.S. industries, the iron and steel
industry consumes 70% of the refractories
produced globally, while the cement and lime
industry consumes 7%, the ceramics industry
6%, the glass industry 3–4%, and the oil
industry about 4%.
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9. Small scale Uses
• Specific applications
– Propulsion systems and friction heating at high
velocities in atmosphere (Aerospace industries)
– Nuclear energy
12. Cost issue
• Compounds of Hf, Cb, Ta, Th, U
• Plasma arc spraying to apply refractory coating
• Special processes to produce refractories of
different shapes
