Destructive factors of refractory materials in electric furnace

Source: | Author:ChangXing Refractory | Published time: 1071 days ago | 767 Views | Share:

In general, the main destructive factors of electric furnace refractories are: erosion, oxidation, erosion, melting, spalling and hydration. Among them, the area occupied is targeted at oxidation, chemical erosion and erosion.

(1) Chemical attack

Iron oxide (FeO) or acidic components in the slag, such as SiO 2 chemically react with CaO and MgO, as shown below:
Chemical attack

Exceeding the reaction can turn the furnace lining into slag, resulting in damage to the refractory material.

(2) Oxidation

Oxidation is one of the leading causes of corrosion of refractory materials in electric furnace linings. In this process, the carbonaceous oxygen fraction (such as iron oxide, oxygen, and magnesium oxide) in the refractory material is oxidized, resulting in decarburization and damage of the material.
chemical reaction

The iron oxide in the slag reacts with the graphite or tar/resin in the hot surface of the brick lining, or oxygen erodes the graphite or the binder on the cold surface of the brick lining. In both cases, the strength of the brick is reduced and the slag may be erosion of molten steel.
Under actual electric furnace atmosphere conditions, starting from above 1700°C, reaction (6) is particularly prone to occur. The generated Mg vapor is easily diffused and tissue destruction occurs. This is one of the main factors that cause high-temperature damage to magnesia carbon bricks.

(3) Scour or mechanical shock

Physical damage is caused by molten steel or molten slag flowing over the surface of the refractory material and physically abrading or scouring the furnace lining. Erosion and erosion are the most common at the tap hole, slag line, electrode hole or exhaust platform of the electric furnace.
Spalling is an intricate damage mechanism of refractory materials. This is caused by the rapid heating and cooling of the lining refractory material, which causes the refractory material to produce stress. This stress often exceeds the strength of the refractory material, resulting in the intersecting and penetrating cracks, and the fragments of the furnace lining will peel off or fall off completely. This situation generally occurs on the roof of the electric furnace.

(4) Hydration

Hydration is also a factor in the destruction of refractory materials in electric furnaces. During use, water easily penetrates into the furnace cover or furnace wall, and water or steam can corrode the refractory furnace lining. Magnesium oxide (or other alkaline oxides) and water (or steam) react as follows to be hydrated.
Hydration

Reaction will cause the performance of refractories to be greatly weakened, and the permeability of slag and molten steel will be deteriorated.
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