Properties required in a refractory

The diversified applications of refractory materials in several different types of industries require diversified properties to meet the physico-chemical and thermal requirements of different phases. In some industrial units more than one phase are present e.g. in steel-making vessels slag /metal /gases are simultaneously present in the vessel at high temperatures. In the heat treating furnaces solid/reducing or oxidizing gases are simultaneously present. Below are briefly described the properties of the refractory materials:

Refractoriness

Refractoriness is a property at which a refractory will deform under it own load. The refractoriness is indicated by PCE (Pyrometric cone equivalent). It should be higher than the application temperatures.
 
Refractoriness decreases when refractory is under load. Therefore more important is refractoriness under load (RUL) rather than refractoriness.

Porosity and Slag permeability

Porosity affects chemical attack by molten slag, metal and gases. Decrease in porosity increases strength and thermal Conductivity.