Influence of Microstructure on Formation of Deterioration Layer in Periclase-Hercynite Bricks

Abstract

The microstructure of the original layer and the cement melt-penetrated layer of a used periclase-hercynite brick from a cement rotary kiln with a daily output of 5000 tons for 12 months was studied by XRD, SEM, EDS, and a mercury porosimeter. The results show that the cation diffusion between hercynite and periclase particles in the brick at high temperatures decreases the pore size of the brick. The pore size in the original layer is located mainly in the range of 4 – 20 μm; the decreased pore size increases the penetration resistance of the cement melt to the inside of the brick and makes the cement melt react with the pore walls better. The components of the matrix pore walls such as MgO and Al₂O₃ dissolve in the cement melt, enhancing the hot properties of the penetrated melt, decreasing the penetration depth, and slowing the formation of the deterioration layer. The pore structure and the element distribution endow the brick with good thermal shock resistance.