Influence on Magnesia Carbon Bricks | Natural Flake Graphite

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Flake Graphite





Carbon Content



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thermal shock resistance, lubricity, conductivity and plasticity…


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Natural flake graphite has superior physical and chemical properties and is widely used in metallurgy, coatings and refractory industries. It is an important non-metallic raw material that is indispensable for today’s high-tech. Flake graphite is divided into large flake graphite and fine flake graphite according to the size of its scales. Usually, large flakes refer to +32 mesh, +50 mesh, +80 mesh, and +100 mesh flake graphite.

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Flake graphite has strong thermal shock resistance and good corrosion resistance and is the main carbon raw material used in carbon-bonded refractories. It has an important influence on the corrosion resistance and high-temperature strength of carbon-bonded refractory materials such as magnesia-carbon bricks. In the actual production process, carbon-bonded refractory materials have strict requirements on purity, ash content, particle size, shape, and an additional amount of flake graphite.

Why does the purity of flake graphite affect magnesia carbon bricks?

1. The high-temperature flexural strength of magnesia-carbon bricks increases with the increase in the purity of flake graphite, which is the result of the difference in the microstructure of magnesia-carbon bricks. Magnesia-carbon bricks made of flake graphite with lower purity have a larger proportion of coarse pores after carbonization at 1000 ° C, and the porosity is also higher than that of products made of high-purity graphite. This may be related to the high flexibility of high-purity graphite and its easy compression when making bricks. Another point is that the structure of magnesia-carbon bricks made of graphite with lower purity is locally weakened. After the magnesia-carbon bricks are treated at a high enough temperature, the silicate minerals associated with graphite melt into a glass phase and react with magnesia or carbon. , so that the original minerals are corroded, the volume is reduced, the contact area is reduced, and a pore zone is formed around the graphite, which leads to a decrease in the high-temperature strength of the magnesia-carbon brick as the graphite’s purity.
The melting rate of magnesia-carbon bricks decreases with the increase in purity, especially for high-carbon flake graphite with a purity greater than 95%.

Flake graphite

2. The study of its mechanism shows that when the temperature is above 1300 ° C, the impurities (SiO2, CaO, Al2O3, Fe2O3, etc.) in magnesia and natural flake graphite will gather at the junction of the two, forming low-melting materials, making magnesia particles susceptible to slag Corrosion into the slag, thereby reducing the corrosion resistance. The results show that the slag resistance of magnesia-carbon bricks with graphite containing more than 95% carbon electricity is 0.5 to 1 times higher than that of ordinary magnesia-carbon bricks.

3. The use of high-carbon flake graphite with a carbon content greater than 95% to 96% is an effective technical measure to improve the quality of magnesia-carbon bricks and reduce the cost of making bricks. If the performance of bricks made of the same grade of flake graphite and magnesia raw materials is used as the benchmark, then switching to high-grade flake graphite will improve the performance of bricks much more than improving the grade of magnesia. Under the same process conditions, the performance of bricks made of high-grade flake graphite and low-grade magnesia raw materials is better than that of high-grade magnesia and low-grade flake graphite raw materials. However, when flake graphite with high purity is used, the liquid phase generated in the brick is less, and oxygen is easy to penetrate the brick to oxidize and decarburize the flake graphite. For this reason, antioxidants such as metal Al, Si, and Al-Mg must be added Alloy, SiC, BN, etc.

Flake graphite

Franli’s factory is one of the suppliers of natural flake graphite, we have been improving technology and using devices for producing high-quality graphite to meet different customers’ demands. We are located in Pingdu, which is the hometown of Graphite. If you want to learn more, welcome.