Analysis on the erosion mechanism of magnesia-zirconia bricks for regenerator of glass kiln
Most domestic glass kiln regenerators use three-layer
magnesia-zirconium checker bricks for the upper part. The bricks are fired in ultra-high temperature tunnel kilns. They are a new type of high-quality magnesia refractory material combined with periclase-forsterite-zircon. . Magnesia-zirconia bricks have produced a large amount of stable forsterite and zirconia before use, and are tightly surrounded by periclase. Due to the strong corrosion resistance of forsterite and zirconia, the corrosion resistance of the brick is improved. The maximum temperature of the upper part of the regenerator is about 1300℃, and the magnesia-zirconia brick can fully resist the impact of high temperature at this temperature. With the exchange of airflow in the regenerator, a large amount of silicon, sodium, calcium in the molten pool glass fly material and a large amount of sulfur and a small amount of phosphorus in the gas adhere to the surface of the brick, gradually invade the inside of the brick, and form sodium, calcium, and magnesium. The sulphate, phosphate and silicate and their composite salts dismember the bonding strength of the bricks at the same time, resulting in a decrease in the strength of the bricks.
1. Erosion of silica
The corrosion of magnesia-zirconia bricks is between periclase and zircon. As the content of SiO2 increases, the ratio of CaO/SiO2 changes and new low-melting silicate phases are formed, such as: diopside ( CMS2), magnesia pyroxene (C3MS2), and forsterite (CMS), etc. The formation of these silicate phases leads to a larger volume effect, causing cracking and peeling of magnesia-zirconia bricks.
2. Corrosion of sulfur and alkali vapor
The used fuel water gas burns to produce a large amount of harmful oxide gases such as sulfur and phosphorus. At the same time, a certain amount of alkali is added as a flux in the production of glass products. These substances adhere to the magnesium during the air exchange process in the regenerator. The surface of the zirconium brick penetrates into the brick, deposits in the pores of the brick and the periclase cleavage surface, and reacts to form new salt substances, magnesium sulfate and anhydrous Glauber's salt (Na2SO4). Change the structure of the brick and destroy the microstructure of the brick, thereby reducing the service life of the magnesia-zirconia brick.
