Yingkou refractories -- characteristics of magnesia carbon bricks

Flake graphite has the following characteristics

1. The melting point and boiling point of high temperature resistant graphite are 3850 + 50, 4250. Even after super high arc burning, the mass loss is very small and the linear expansion coefficient is very small. The strength of graphite strengthened with the increase of temperature, and the strength of graphite increased by 2000 times.

2 conductivity and thermal conductivity. The conductivity of graphite is twice higher than that of ordinary nonmetallic minerals. Thermal conductivity exceeds metal materials such as rigid, iron and lead. The thermal conductivity decreases with increasing temperature, and even at high temperature, graphite is adiabatic.

3 lubricity. The lubricity of graphite depends on the size of graphite flake. The larger the flake, the smaller the friction coefficient, the better the lubrication performance.

4 Chemical stability, graphite at room temperature has good chemical stability, acid resistance, alkali resistance, corrosion resistance of organic solvents

5 plasticity. Graphite has good toughness and can be rolled into thin sheets.

6 thermal shock resistance. Graphite can withstand drastic changes in temperature without damage when used at high temperature. When the temperature changes suddenly, the volume of graphite changes little, and no cracks will occur.

Binder plays the role of linking matrix and particles. In the actual production and use process, matrix and binder system are two weak links of magnesia-carbon brick.

The requirements for the production of magnesia carbon bricks for binding agents are as follows:

1, it has a certain viscosity and fluidity, and has good wettability for magnesia and graphite.

The 2 bond can be further condensed in the heat treatment process, so that the product has a higher strength.

3 during heat treatment, the binder does not cause excessive expansion and shrinkage of the product, so as to avoid cracking.

The 4F.C content is high, and the carbonaceous polymer after coking treatment has good high temperature strength.

Coal tar, coal tar, special carbon resin, polyols, asphalt modified phenolic resin, synthetic phenolic resin and so on are commonly used in the production of magnesia-carbon bricks.

Antioxidant

The excellent performance of magnesia-carbon brick depends on the existence of carbon in the brick. The oxidation of carbon in the process of using magnesia-carbon brick can easily cause the structure deterioration of the product, make slag invade the brick along the crevice, erode magnesia particles, and reduce the service life of magnesia-carbon brick. At present, oxidation resistance of magnesia carbon bricks is mainly improved by adding antioxidants.

The principle of choosing antioxidants

1 according to thermodynamic data and conditions of use, it is possible to determine the possible condensate phases and the vapor pressure of each vapor phase.

2 comparing the size of each condensed phase with oxygen affinity and the possibility of CO reaction.

3 analyze the influence of various tombs' brick microstructure.