Magnesium-carbon brick is made of high melting point alkaline oxide magnesium oxide (melting point 2800 C) and high melting point carbon material which is difficult to be attacked by slag. Dashiqiao refractory is added with various non-oxide additives. Non carbonaceous composite refractories made from carbon binder.

Magnesium-carbon brick is made of high melting point alkaline oxide magnesium oxide (melting point 2800) and high melting point carbon material which is difficult to be attacked by slag as raw materials, adding various non-oxide additives. Non carbonaceous composite refractories made from carbon binder. Magnesium-carbon brick is mainly used in the lining of converter, AC arc furnace, DC arc furnace and slag line of ladle.

As a composite refractory, magnesia-carbon brick effectively utilizes the strong slag corrosion resistance of magnesia, the high thermal conductivity and low expansion of carbon, and compensates the biggest disadvantage of poor spalling resistance of magnesia.

Its main characteristics are as follows: 1. It has good high temperature resistance, 2 slag resistance, 3 thermal shock resistance and 4 high temperature creep.

Effect of raw materials on properties of magnesia carbon bricks

The quality of magnesia has a very important influence on the performance of magnesia-carbon brick. How to select magnesia reasonably is the key to produce magnesia-carbon brick. Magnesia has fused magnesia and sintered magnesia, which have different characteristics. Fused magnesia: grain size is large, impurities are few, silicate phase is small, grain direct bonding degree is high, grain boundaries are few.

Sintered magnesia: grain is fine, impurity is more than silicate phase, and the degree of direct bonding is poor.

As for magnesia raw material, besides chemical composition, it also requires high density and large crystallization in structure. Therefore, as the quality index of magnesia raw material for producing magnesia-carbon brick, the following contents should be investigated: 1. Magnesium oxide content (purity). 2. the types of impurities, especially.C/S and B2O3 contents. 3. magnesia density, pore size and stomatal morphology (sinterability).

The purity of magnesia has great influence on slag resistance of magnesia carbon bricks. The higher the content of MgO, the less the impurities, the lower the degree of silicate phase separation, the higher the direct binding of brucite, the higher the slag penetration resistance and slag melting loss. The main impurities in magnesia are calcium oxide, silicon dioxide, iron oxide, [1] If the content of impurities is high, especially boron oxide compounds, it will have a negative impact on the fire resistance and high temperature performance of magnesia.

Impurities in magnesia mainly have the following adverse effects: 1. Reducing the direct bonding degree of periclase 2. Forming low-melt ferric oxide with magnesia at high temperature 2. Silica and other impurities at 1500-1800 C, reacting with carbon before magnesia, leaving pores to make the slag resistance of products worse.

For magnesia raw materials, besides the total amount of impurities, the type of impurities and the relative content of magnesia also have a significant impact on the performance of magnesia. CaO/SiO 2 ratio and B2O 3 content have the most obvious influence. Generally speaking, magnesia refractories require CaO/SiO 2 (>2) to improve the high temperature stability of magnesia-carbon bricks.

The carbon materials used to prepare magnesia carbon bricks are mainly flake graphite.