The high temperature compressive strength of refractory material refers to the pressure that the material can bear per unit area under the high temperature hot state higher than 1000~2000 ℃, expressed in N/mm².

The effect of temperature

The compressive strength of refractory bricks generally changes obviously with the increase of temperature. When the temperature rises from normal temperature, it decreases linearly with the temperature. Since then, some materials continue to decline with the increase of temperature. When the temperature rises to a certain range, some will rise with the temperature. It reaches a peak at a certain temperature, and then drops sharply.

The effect of composition of refractory material

The change of high temperature compressive strength of refractory is controlled by the change of some components in the material, especially the matrix or its combination phase at high temperature. Generally speaking, sintered refractories made entirely of crystals are prone to plastic deformation of grains and grain boundaries at high temperatures. Especially when the loading speed is small, plastic deformation is more likely to occur. So its strength decreases with the increase of temperature.

When some or all of the crystalline phases melt or form a molten body at high temperature, their strength often drops sharply. In addition to crystals, some refractories also contain a certain amount of glass phase. Such as silica brick, clay brick and high-alumina refractory brick. Their matrix is mainly composed of glass phase. With the increase of temperature, the strength of these multiphase materials also decreases with the change of temperature.

However, when the temperature is further increased, the viscosity of the glass phase changes from brittleness to toughness. This will make the bonding between material particles more firm. Therefore, the strength is significantly improved. Then, when the temperature continues to rise, the viscosity of the melt in the product decreases sharply, and the strength decreases with the sharp decrease of the melt viscosity.

When the refractory contains a certain amount of binder that changes with temperature, the strength of the product will fluctuate with the rise of temperature.