Insulating castable refractory typically has a maximum service temperature in the range of 1800 to 2200°F, depending on the specific composition and additives used. Insulating castables are refractory concretes designed to have lower thermal conductivity, making them suitable for insulating lining applications where heat loss needs to be minimized. The most common insulating castable types are high alumina insulating castable and chromite insulating castable. Their maximum service temperatures tend to be:
High alumina insulating castable: 1800 to 2000°F
Chromite insulating castable: 2000 to 2200°F
The maximum service temperature of an insulating castable depends on factors like:
Chemical composition:
Compounds with higher refractory oxides like alumina or chromia can withstand higher temperatures.
Additives and impurities:
Additives like silica or magnesium oxide can lower the maximum service temperature.
Grain size of refractory aggregates:
Finer grain sizes tend to result in slightly lower maximum service temperatures.
Castable application and firing conditions:
How well the castable is mixed, placed and cured can impact its maximum service temperature.
Thermal shock resistance:
Insulating castables are more prone to spalling at high temperatures due to low mechanical strength. This can effectively limit their maximum service temperature in some applications.