Any material can be described as a  refractory  if it can withstand the action of abrasive or corrosive solids, liquids or gases at high temperatures. The various combinations of operating conditions, in which refractories are used, make it necessary to manufacture a range of refractory materials with different properties. Refractory materials are made in varying combinations and shapes depending on their applications. Refractories are useful in constructing application-specific high temperature areas/surfaces, particularly in furnaces or boilers, as they minimize heat losses through structure

General requirements of a refractory material are

• Withstand high temperatures
• Withstand sudden changes of temperatures
• Withstand load and abrasive forces
• Withstand action of molten metal slag, glass, hot gases
• Withstand load at service conditions
• Conserve heat
• Have low coefficient of thermal expansion
• Should not contaminate the material with which it comes into contact

Role of refractory

Refractory materials have a crucial impact on the cost and quality of steel products. The diversification on steel products and their cleanliness requirement in recent years have increased the demand for high quality refractory. Steelmaking requires high temperatures of the order of 1600 degree centigrade. In addition steelmaking handles high temperature phases like molten steel, slag and hot gases. These phases are chemically reactive; refractory materials are required to produces steels. High quality refractory at a cheaper cost is the main requirement because cost of refractory adds into the cost of product.

Refractory requirements:

The refractory materials should be able to withstand

• High temperature
• Sudden changes of temperature
• Load at service conditions
• Chemical and abrasive action of phases