About the service life of silicon carbon rods

The service life of silicon carbon rod is affected by the following points:

1, the use of temperature

The higher the temperature of the silicon carbon rod, the shorter the life. 

Especially after the furnace temperature exceeds 1600 ° C, the oxidation rate is accelerated, and the service life of the silicon carbon rod is shorter, 

so please try not to let the surface temperature of the silicon carbon rod is too high, that is, it is necessary to reduce the difference between the furnace temperature and the silicon carbon rod temperature.

2, surface load

Surface load density refers to the allowable load rating power per unit surface area of the heating part of the rod.

Surface load density = rated power (W)/heating surface area (cm2)

Practice has proved that the difference between the surface temperature of the heating body and the furnace temperature is also large when the load density is large. 

With high load density, the surface temperature of the rod is high, the resistance increases quickly, and the life of the SIC rod is short. 

Therefore, the silicon carbon rod surface temperature load density, furnace atmosphere, temperature is proportional to the aging rate of SIC rod, and inversely proportional to the life of SIC rod.

3, the atmosphere in the furnace

In the process of use, the silicon carbon rod will react with many chemical substances volatilized from the sintering, and if it is in contact with water, hydrogen, nitrogen, sulfur, halogen and other gases and molten aluminum, alkali, salt, molten metal, metal oxide, reaction, corrosion or oxidation will also occur, thereby reducing the service life of the silicon carbon rod.

4, kiln operation mode

In continuous kiln and intermittent kiln, the life of silicon carbon rod is longer. 

The surface of the silicon carbon rod is oxidized to form a silicon dioxide film during use, and the resistance value of the silicon carbon rod increases with the increase of the silicon dioxide film after long-term use. 

The silica film expands and contracts abnormally near the critical point of crystallization (270℃). Because the intermittent use in the intermittent kiln always fluctuates up and down at this temperature,

 the silica film is repeatedly broken and the oxidation is accelerated. Therefore, when the furnace temperature drops to room temperature, the resistance is often increased sharply.

5, wiring method

If the resistance value of the silicon carbon rod is different, the load of the silicon carbon rod with high resistance is concentrated in series, 

which easily leads to a rapid increase in the resistance of a silicon carbon rod and a short life. Silicon carbon rods are generally used in combination with series and parallel wiring.

 It is recommended to use 2 strings in series for one group and then multiple groups in parallel. Especially when the temperature in the furnace exceeds 1350℃, 

it must be connected in parallel. Open triangle cables are recommended for three-phase connections.