Refractory brick process of used, to withstand high temperatures, temperature changes, atmospheric changes, and erosion by dust, smoke, metal melt, and slag, its destruction mechanism is very complex, and it is difficult to make a correct judgment.
The destruction of refractory bricks during use is not only slag erosion (continuous type) but also fracture and flaking (discontinuous type).
After a comprehensive analysis of the results of the use of refractory bricks, it is possible to classify the damage mechanism of refractory bricks.
1. Damage due to mechanical and thermal stresses in the structure, resulting in irregular cracks (thermal, mechanical spalling, or flaking) in the refractory work lining.
2. Structural changes in the refractory brick due to slag infiltration and temperature fluctuations on the hot surface (working surface).
As a result, a characteristic metamorphic layer is formed, and cracks (structural spalling) parallel to the heating surface are produced at the intersection of the original and metamorphic layers and are destroyed.
3. Due to the reaction with the metal melt, slag, and soot and dissolved flow and wear, mainly due to the production of the liquid phase and the working surface layer melting corrosion (melt loss).
Refractory bricks are thermodynamically unstable in the process of use.
Therefore, the direction of research and development of refractory bricks is to create kinetic barriers in (and near) the refractory bricks to resist deterioration caused by eventual irreversible structural and compositional changes.
From the point of view of phase equilibrium or thermodynamics, a non-reactive composition of the refractory brick in contact with the slag does not exist.
Therefore, a protective layer is formed on the surface of the refractory brick, and the dissolution of this layer is slowed down as much as possible to keep the damage caused by slag erosion to a minimum.
To reduce the rate of dissolution (diffusion) of the protective layer, the composition of the protective layer should be as high as possible a high melting point substance or a high viscosity solution that is close to the heterogeneous equilibrium of the slag and the non-homogeneous system.
