Cordierites (Mg,Fe2+)2(Al2Si)[Al2Si4O18] have a very low coefficient of dilation. So they are very resistant against temperature changes and have a good mechanical strength.
The cordierites are divided into porous or thick cordierite. The porous cordierite is not as stable against deflection as the thick one. But therefore porous cordierite has a higher resistance against temperature changes than thick cordierite. The porous structure helps to lower the mechanical pressure.
To summarize: Cordierite combines following characteristics:
- good strength at high temperatures
- high resistance to temperature changes
- does not react by contact with alloy of heating conductors