The damage process of magnesia carbon brick

 

The damage process of magnesia carbon brick: the damage of magnesia carbon brick is firstly due to the oxidation of carbon in the brick to form a decarburized layer, plus the difference in thermal expansion rate between magnesium oxide and graphite at high temperatures (1.4% and 0.% at 1000 ℃, respectively) ), Leading to loose structure, reduced strength, and then eroded by slag, mechanical erosion, etc., the magnesium oxide particles in the brick are gradually eroded, falling off layer by layer, causing damage to the magnesium carbon brick. The damage process of magnesia carbon brick is: oxidation → decarburization → looseness → erosion → erosion → shedding → damage.
The damage of the magnesia carbon brick is firstly the oxidation of the carbon in the hot surface of the working lining to form a thin decarburized layer. The oxidation of the carbon is due to the continuous oxidation of iron oxides in the slag and O? in the air and oxides such as CO?, SiO? The result of oxidation, and the vaporization of carbon dissolved by MgO dissolved in molten steel or brick; followed by high-temperature liquid slag penetration into the pores of the decarburized layer or cracks due to thermal effects, and oxidation in the brick Magnesium reacts to form a low-melting compound, which causes the surface layer of the brick to become qualitatively weakened and weakened. Under strong steel slag agitation, mechanical scouring and other stress, the layer is peeled off layer by layer, resulting in the destruction of the magnesium carbon brick. Eventually make up the furnace, repair the furnace, and stop the furnace.
(1) Carbon oxidation
Due to the oxidation of carbon, the carbon network structure in the brick is destroyed, so that the organizational structure is loose, the strength of the product is reduced, and the pores are increased, which also exacerbates the erosion of the brick by the slag.
() The effect of stomata
The pores in the magnesia-carbon brick, especially the open pores, have an important influence on the damage of the magnesia carbon brick for sale. During the use of magnesia-carbon bricks, the oxidation damage of carbon is mainly promoted through the pores, which further aggravates the erosion of the brick lining by the slag, thereby causing the damage of the magnesia-carbon bricks. The open pores existing in the brick draw air from the outside when cooling. When reheating, the oxygen in the air reacts with the surrounding carbon to form CO and is discharged. This process repeats itself and increases the porosity. In addition, the binder present in the magnesia-carbon brick is an important factor in the generation of pores.
As a binder of magnesium carbon bricks, phenolic resin is often used. Adding 3% ~ 4% phenolic resin, the porosity after molding is low, about 3%. However, during the use process, the phenolic resin is heated and decomposed, and H?O, H?, CH?, CO, CO? and other gases are evaporated and discharged, and the gas evaporation path forms pores, which also increases the porosity.

In this way, the oxygen in the air and the oxides in the slag will erode the brick through the pores. On the one hand, it promotes the oxidative damage of carbon, on the other hand, it intensifies the reaction between the slag and the MgO in the brick, resulting in the magnesium carbon brick damage. This process is repeated from time to time. On the one hand, through the oxidation of carbon and the erosion of slag, the carbon network structure in the brick is destroyed, the structure is loose, and the high temperature strength is reduced. As a result, under the action of strong steel slag agitation, mechanical scouring, thermal shock and other stresses, it will fall off layer by layer, causing damage to the magnesium carbon brick.

Article Source:The damage process of magnesia carbon brick

Company name：Wanhao Refractory

Email:sales100@wanhaorefractory.com

Website: http://www.wanhaorefractory.com/



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