How do pores in refractory materials affect their strength and thermal-shock resistance?

In the context of industrial refractory materials, the presence of pores significantly influences both mechanical integrity and durability under temperature fluctuations.

• Impact on Strength: The inclusion of large amounts of air spaces, or pores, within the material's microstructure generally reduces its load-bearing strength.1
• Impact on Thermal-Shock Resistance: While pores decrease overall strength, they serve a critical functional purpose by blunting the propagation of cracks. When a material undergoes rapid cooling, the resulting contraction creates tensile stress that can lead to failure; however, the presence of pores and large filler grains helps arrest these cracks, thereby reducing the material's susceptibility to thermal shock.1

It is important to note that while porosity is beneficial for thermal-shock resistance, it is often undesirable in environments involving corrosive substances, such as glass-melting furnaces. In those applications, manufacturers prioritize higher density and lower porosity to maintain chemical integrity.1