Measures to Improve the Service Life of Magnesia Carbon Brick

Magnesia-carbon bricks are products made of sintered magnesia or fused magnesia and carbon material graphite as raw materials, with carbon-containing resin as a binder, mixed, molded and heat treated at about 220°C.

The main characteristics of magnesia carbon bricks

① The normal temperature strength of magnesia carbon bricks is low. In order to improve the density and strength of high-grade bricks, they must be formed under high pressure.

② Magnesia carbon bricks have good thermal shock resistance.

③Magnesia carbon bricks have strong slag resistance.

④The carbon in magnesia carbon bricks is easily oxidized.

What technical measures should be taken to improve the service life of magnesia carbon bricks?

01 Increase the proportion of large-grained magnesia and increase the volume density of the furnace lining

The use of high-purity, large crystalline magnesia helps improve the corrosion resistance and oxidation resistance of magnesia carbon bricks.

02Using high-purity graphite

The type and particle size distribution of graphite have an impact on the porosity, high-temperature strength and MgO-C reaction of bricks in oxidizing and reducing atmospheres after carbonization.

03 Add additives

Metal additives such as Al, Si, Mg or their mixtures and alloys can prevent graphite from oxidizing, and the carbides formed can improve the mechanical properties of the bricks.

Non-oxide additives such as borides, carbides, and nitrides have high oxygen affinity, and their oxides can form a liquid protective layer on the surface of the brick.

04 Oil immersion

At high temperatures, the escape of CO in magnesia-carbon bricks will cause carbon loss, and the increase in apparent porosity after carbonization will affect its service life. Oil-immersing the bricks can seal the pores, reduce the porosity after carbonization, and improve the corrosion resistance. This is also a way to improve the quality of magnesia-carbon bricks.

05 Choose the right binding agent

Phenolic resin binder has high carbon residue after pyrolysis, with a high carbon residue of 50% to 60%. The hardened high-polymer resin has good uniformity, few defects in the network structure, high strength, and less environmental pollution.

Asphalt binders can be better graphitized and have higher antioxidant stability. However, cracks are easy to occur inside the bonded carbon and the strength of the product will be reduced.

The application of asphalt-resin composite can form a fine mosaic structure, enhance the fracture toughness of the carbon bond, strengthen the carbon bond, and improve the oxidation resistance.

Choose the right binding agent can help to improve the service life of the brick.