What refractory materials are generally used for electric furnace cover

The electric furnace cover is subjected to high temperatures and rapid cooling and heating, which places high demands on refractory materials. The refractory materials used in the electric furnace cover in China have evolved from the large pieces of special-shaped siliceous composite bricks initially used to the unburned high-alumina bricks prepared by adding various binders (water glass, phosphoric acid, aluminum dihydrogen phosphate, και τα λοιπά.), or the introduction of sillimanite mineral raw materials in the ingredients, the addition of micropowder, spinel, καρβίδιο του πυριτίου, και τα λοιπά. In recent years, various types of refractory castables have been developed to meet the needs of the development of ultra-high-power electric furnaces. The refractory materials used in the electric furnace cover are as follows.

High alumina brick furnace cover

The fired τούβλα υψηλής αλουμίνας with corundum as the main crystal phase can be used for the cover of ultra-high power electric furnaces, with a service life of about 150 furnaces. Preventing spalling and improving erosion resistance are the keys to delaying the damage of refractory bricks.

Furnace cover bricks containing “three stones”

The “three stones” include sillimanite, kyanite, and andalusite, which belong to the sillimanite family of minerals and are allomorphs. Their theoretical composition is A1203:53.1%, Si02:36.9%. The three raw materials are all high-aluminum minerals and have the properties of high-aluminum minerals. The “three stones” are heated to a certain temperature and irreversibly transformed into mullite crystals (short columnar and needle-shaped network structures). The expansion rate of the “three stones” is related to the purity, particle size, impurity composition, and content of each mineral. Andalusite and sillimanite have small volume expansion and good volume stability when they are transformed into mullite, so they can be directly made into bricks without pre-burning or partially introduced for use. Kyanite can be used as an expansion agent for amorphous refractory materials or partially introduced into brickmaking due to its large volume expansion.

Unfired furnace cover bricks

Unfired electric furnace cover bricks are a new variety that has developed in recent years. Their advantages are simplified production process, energy saving, good thermal shock resistance and corrosion resistance, but slightly poor structural strength, performance and storage period are greatly affected by packaging methods and environment. Adding SiC, MgO, AI203, ντο, και τα λοιπά., to high-aluminum unfired bricks or treating them with lightly fired oil immersion is an effective measure to improve the high-temperature performance of furnace cover bricks. Chemically bonded bricks with SiC have good thermal shock resistance and corrosion resistance.

Integrally cast furnace cover

Refractory prefabricated blocks are used in the triangular area of ​​the electric furnace cover. The main materials are corundum, chrome corundum, high alumina, κηλίδα, και τα λοιπά. The refractory prefabricated blocks have good integrity and corrosion resistance, simple masonry construction, and relatively guaranteed construction quality, which greatly improves the overall quality of the electric furnace cover. Γενικά, the triangular area of ​​the ultra-high power electric furnace cover adopts corundum (chrome corundum) prefabricated parts. High alumina and mullite prefabricated blocks are widely used in the triangular area of ​​the high-power electric furnace cover.